Fundamentals of Chemistry
Fundamentals of Chemistry CHEM 1332
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1332 SECTION 16 REVIEW Insoluble Salts weak electrolytes Cationn Anionms cgt n Cationaq m Anionaq Q or Ksp Cation n Anion In Every salt has a value for Ksp at a given temperature If Q Ksp solution is SATURATED in given salt Solubility Measure of how to make saturated solution Either gram solubility how many grams in a given volume or MOLAR solubility S how many moles per liter of saturated solution Relationships between S and Ksp 1 write out equation for dissolving and dissociation of salt must know ions from Chap 2 2 write out Ksp expression 3 express concentration of ions in terms of S 7 USING SIMPLE STOICHIOMETRY 4 substitute into Ksp expression to get relationship between Ksp and S For example AgCl 1 AgC1s cgt Agaq C1aq 2 Ksp Agl11CI391 3 Ag s 0139 s 4 Ksp S Agz zu 1 Ag m 2A2gaqs04239aq 2 Ksp1Ag1 s04 1 3 Ag12s1s04 391s 4 Ksp 4S Other Uses of Ksp a Determine whether precipitate will form Calculate Q from given concentrations and compare to Ksp Q lt Ksp unsaturated solution Q Ksp saturated solution Q gt Ksp precipitate will form b How much to add to make a precipitate Plug in knowns into Ksp expression will be left with needed concentration c Common Ion Effect 7 what is solubility in ali erent solution Assume solubility small plug in knowns as in b Presence of extra ion will reduce solubility al E ects of Acid and Base Acid will increase solubility if it can react neutralize anion all except from strong acids Base will increase solubility if it can react neutralize cation all except group 1 and 2 cations e What is concentration of one ion if given Ksp and concentration of other ions39 Simply plug knowns in to Ksp expression REMEMBER ONLY USE Ksp FOR INSOLUBLE THINGS ALL OTHER SOLUTIONS ARE THERE TO GIVE YOU IONS ONLY Watch for tricks Think about where ions came from do you multiply by stoichiometry of insoluble salt or not usually yes when using S as molar solubility NO when ions comes from elsewhere Remember pH or pOH can give you H or 0H 1332 Questions on Section 16 Ksp Some useful data Compound Ksp Compound Ksp AgCl 18 x 1010 AngrO4 9 x 1012 PbSO4 18 x 108 CaF2 40 x 1011 MgOH2 15 x 1011 BaSO4 11X 10 10 Simple Introductory Stuff A B C To what kind of solutions is the proper use of the solubility product principle limited dilute solutions of moderately soluble electrolytes dilute solutions of slightly soluble electrolytes saturated solutions of moderately soluble electrolytes saturated solutions of slightly soluble electrolytes supersaturated solutions of moderately soluble electrolytes Which is the correct expression for the solubility product constant for Ag2CrO4 D E Ksp Ago2 Cr0421 Ksp Ago Cr0421 Ksp 2Ag1 Cr0421 Ksp zAgu2 Cr0421 Ksp Agn Cr0421 Ksp and Solubility A A A A A If the concentration of a saturated solution of SrCO3 is 0000040 mol L l what is the value for the solubility product constant of this salt 4 711 77 40 x10 B 16 x10 9 C 40 x10 5 D 16 x10 E 16 x10 The solubility of Cu2CrO4 in water at 25 C is l X 10 4 mol L l The solubility product constant at this temperature is 1x1012 B 4x1012 C 1x108 D 4x108 What is the solubility product constant Ksp of leCrO4 given that the molar concentration of CrO4239 in a saturated solution made by dissolving leCrO4s in water is 63 X 10395 M 25 x10 B 40 x109 C 10 x1012 D 80 x109 E 63 x105 What is the KSp of Mg3PO42 in water at 25 C if its molar solubility is 86 X 10396 47 x10 B 51 x 1039 C 80 x108 D 86 x107 E 74 x1011 The solubility of the ionic compound Ca3PO42 is 0020 moles per liter Calculate the Ksp 15x10397 64X103911 80X10396 l 35 x107 B 32 x109 C D E A The solubility of BaCO3 is 79 X 10 3 g L l Calculate the solubility product Ksp ignoring hydrolysis 16 x10 2 B 40 x10 5 C 16 x10 9 D 62 x10 5 The solubility of silver acetate AgC2H302 is 102 g per 100 mL What is the Ksp 37 x105 B 28 x104 C 10 x104 D 37 x103 Calculate the molar solubility of Ag2CrO4 723 w 4 4 4 81X10 B 3x10 C 21x10 D 17x10 E 13x10 Given that the KSp for strontium uoride Ser is 26 X 10399 calculate the solubility in pure water 14x10393 B 34x10394 C 87x10quot D 51x10394 E 26X10399 Other Concentrations 12 A D A D Calculate the concentration of Fe in blood which is saturated in Fe3using the fact that the pH 741 and the Ks ofFeOH3 is 40 x 1039 24x103918 M B 20X103910M 13 x1038 M E 12 x1019 M C 40 x 103938 M What is OH in a saturated solution of MgOH2 where Mg2 15 X 10 5 M 22 x1010 M B 50 x104 M C 30 x105 M D 10 x103 M Silver chloride is precipitated by adding HCl to a solution of a silver salt until the concentration of chloride ions Cl is 020 M Neglecting the effects of interatomic attraction what is the concentration of silver ions 00042 M B 18 x1010 M C 00095 M D 90 x1010 M Typical hard water contains about 20 X 10 3 mol of Ca2 per liter Calculate the maXimum concentration of uoride ion which could be present in hard water 20 x103 M D 20 x108 M 14 x104 M B 40 x103 M C What is the concentration of AgJr in a 0010 M KCl solution saturated with AgCl 13 x105 M B 18 x108 M C 10 x107 M D 18 x 1011 M What is the molar concentration of silver ion in a solution containing 13 X 10 4 M CrO42 saturated with AngrO4 13x 1016 B 7x 1016 7 x 103 E 26 x 104 C 9 x 1012 Common Ion 18 Iftvvo salts AX and BX2 have the same Ksp values of 40 X 10 12 then A their molar solubilities in water are the same B the salts are more soluble in 01 M NaX than in water C the molar solubility of AX in water is less than that of BX2 D addition of NaX will not affect the solubilities of the salts 19 What is the molar solubility of lead sulfate in 10 X 10 3 M Na2S04 A 18 x102 B 18 x105 C 13 x104 D 50 x106 20 The KSp obeClz is 17 X 10395 Calculate its molar solubility in a solution that is 0200 M NaCl A 43 x105 B 85 x105 C 43 x10quot D 41 x 10393 E 41x10quot 21 For which salt would the solubility be MOST sensitive to pH A CaNO32 B Can C CaCl2 D CaBr2 E CaI2 22 Which of the following salts would NOT be more soluble in acidic solution A MgOH2 B AgCl C Ag3PO4 D AgF 23 For which salt of the following pairs will the solubility depend on pH i PbFz PbClz ii SrN032 SrNOz2 A They all depend on pH B i PbClz ii SrNOz2 C i PbCl2 ii SrNOZ2 D i PbF2 ii SrNOZ2 E i PbFz ii SrN032 Precipitation 24 The addition of solid Na2S04 to an aqueous solution in equilibrium with solid BaSO4 will cause A no change in Ba2 in solution B more BaSO4 to dissolve C precipitation of more BaSO4 D an increase in the Ksp of BaSO4 25 Which of the following miXtures would result in the formation of a precipitate A 010 M NaN03 and 005 M BaCl2 B 1x 10398 M Na2S04 and 00005 M M BaCl2 C 1 x 10395 M Fe2SO43 and 1 x 10395 M BaCl2 D 1 x 10392 M CuS04 and 1 x 10398 M BaCl2 26 In a solution of 20 X 10393 M Pb2aq what is the concentration of I39 necessary to just begin precipitation of PbI2 Ksp 14 x 10 A 14X10398M B 26X10393M C 49x103911M D 28x103911M E 70X10396M 27 Given the following values of Ksp select the mixture below that would give rise to the formation of a precipitate Aga Ksp18x1039m Bamm Ksp11x1039m sz K79X109 Chg K32X10 1gCN Ksp22x1039m A A solution that is 100 x 10395 M AgNo3 and 100 x 10395 M NaCl B A solution that is 100 X 10394 M BaN032 and 100 X 10396 M NaZSO4 C A solution that is 100 X 10393 M PbNO32 and 200 X 10393 M NaI D A solution that is 100 X 10393 M CaNO32 and 200 X 10394 M NaF E A solution that is 100 x 10398 M AgNo3 and 200 x 10398 M NaCN 28 Which answer best describes what happens when 750 mL of 400 X 10393 M CeN033 is added to 3000 mL d200XH h4KKkK19X10m nCdKLb A QSp 53 X 1039 precipitate will not form B QSp 16 X 10395 precipitate will not form C QSp 53 X 1039 precipitate will form D QSp 16 X 10395 precipitate will form E QSp 80 X 10395 precipitate will form 29 Which answer best describes what happens when 0200 L of 0060 M NaOH is added to 0100 L of 030 M CaN032 KSp 65 X 10396 for CaOH2 A QSp 12 X 10393 precipitate will not form B QSp 18 X 10392 precipitate will form C QSp 16 X 10394 precipitate will form D QSp 16 X 10394 precipitate will not form E QSp 12 X 10393 precipitate will form ANSWERS DABBClBACDElCADDAlBBCBClBBDCClBDCC A C CHEM 1332 CHAPTER 14 Which is a proper description of chemical equilibrium The frequencies of reactant and of product collisions are identical The concentrations of products and reactants are identical The velocities of product and reactant molecules are identical Reactant molecules are forming products as fast as product molecules are reacting to form reactants The numbers of moles of reactants and products are equal Chemical equilibrium is the result of the unavailability of one of the reactants opposing reactions attaining equal speeds a decrease in speed of reaction B a stoppage of further reaction D formation of products equal in mass to the reactants The value of the equilibrium constant K for a reaction at equilibrium is altered by changing the temperature B adding a catalyst C changing the effective concentration of reactants changing the effective concentration of products adding water When a chemical system is at equilibrium the concentrations of the reactants are equal to the concentrations of the products the forward and reverse reactions have stopped the reaction quotient Q has reached a maximum the concentrations of the reactants and products have reached constant values none of these Which of these statements is NOT TRUE the equilibrium constant is independent of temperature a system that is disturbed from an equilibrium condition responds in a manner to restore equilibrium equilibrium is molecular systems is dynamic with two opposing processes balancing each other the value of the equilibrium constant for a given reaction mixture is the same regardless of the direction from which equilibrium is attained a system evolves spontaneously toward a state of equilibrium What is the equilibrium constant expression Kc for the gas phase oxidation of CO to C02 by means of Oz L212 m K CO 02 B 002 7 00212 7 CO 02 K 0012 02 D K 002 7 Calculate Kp for HzOg 12 Ozg cgt HzOzg at 600 K using the following data H2g 02g cgt H202g Kp 23 x 106 at 600 K 2 Hzg 02g cgt 2 HzOg Kp 18 x 1037 at 600 K A 26 x1031 8 A C E A C A B 44 x1043 C 98 x1024 D 12 x10quot4 E 54 x10quot13 For the aqueous reaction A 2 B cgt 3 C 4 D I mix 1 mole of A 2 moles of B 1 mole ofC and 2 moles of D in a 1 L container If the equilibrium constant Kc at this temperature is 5 then the reaction mixture is at equilibrium B the reaction will proceed to the left the reaction will proceed to the right D none of these are correct the products will be MUCH smaller than the reactants at equilibrium The equilibrium constant Kc for the gaseous reaction C D cgt E 2F is 30 at 50 0C In a 20 L ask at 50 0C are placed 10 mol of C 10 mol of D 10 mol of E and 30 mol of F Initially the reaction will proceed at equal rates in both directions B proceed more rapidly to form E and F proceed more rapidly to form C and D D not occur in either direction The equilibrium constants Kc and Kp will equal each other when all of the reactants and products are gases the number of moles of gaseous products is greater than the number of moles of gaseous reactants the number of moles of gaseous products is less than the number of moles of gaseous reactants the number of moles of gaseous products is equal to the number of moles of gaseous reactants they are never equal to each other Kp at 25 C for the reaction NOzg cgt NOg 02g is 448 x 103913 Calculate the value for Kc 181 x 103916 B 448 x10quot13 111x10399 E 183 x 103914 C cannot be determined Consider the exothermic reaction N2g 3H2g cgt 2NH3g AH 7921 k At 400 K the equilibrium constant Kc is 053 Calculate Kp for the reaction at 400 K 053 B 174 C 752 D 0016 E 49 x 10394 Nitric oxide and bromine were allowed to react in a sealed container according to the equation NOg Brzg cgt NOBrg At equilibrium pNO 0526 atm pBrz 159 atm and pNOBr 768 atm Calculate Kp for the reaction 745 x 10393 B 0109 C 918 D 134 E 768 Calculate K c for the reaction N2g 3H2g cgt 2NH3g when the equilibrium concentration moles per liter are N2 002 Hz 001 NH3 010 2 x 106 B 5 x 103 C 5x105 D 5x 107 A A D 20 A 21 A 22 A A 120L ask contains an equilibrium mixture of 00168 mol of N2 02064 mol of Hz and 00143 mol of NH3 Calculate Kc for the reaction N2g 3H2g cgt 2NH3g 138 B 496 199 C 412 D Under a set of equilibrium conditions HI 010 M and H2 1 Calculate the concentration of 12 if the equilibrium constant K 0016 2HIg cgt H2g Izg 13 x10 2 M B 31 x 10 1 M C 40 x10 2 M D 13 M Given the equilibrium equation A2 B cgt 2AB At 25 0C the equilibrium concentrations in moles per liter are A2 040 B2 040 AB 120 What is the value of the equilibrium constant K 011 B 013 C 18 D 75 E 90 The equilibrium constant Kc for the reaction 2HBrg cgt H2g Brzg is 10 at a certain temperature when concentrations are expressed in moles per liter Calculate the number of moles of HBrg present at equilibrium if 100 L of the equilibrium mixture contain 5 mol of Hug and 8 mol of Brug 025 B 05 C 1 D 2 E 4 For the reaction COg Clzg cgt COClzg Kc 51 x 109 at a particular temperature Pure COClz is added to a 1 liter ask At equilibrium it is found that 025 moles of COClz remain What is the equilibrium concentration of CO 70 x10quot6 M C 49 x103911M none of these 14 x 10395 M B 075 M E At a certain temperature 0500 mol of PC15 was placed into a 0250 L vessel and permitted to react as shown At equilibrium the container held 0100 mol of PC15 What is the value of Kc PC15g cgt PC13g Clzg 12 B 20 C 64 D 10 One mole of a compound AB reacts with one mole of a compound CD according to AB CD cgt AD CB When equilibrium has been established it is found that 075 mol of each of the reactants AB and CD has been converted to AD and CB There is no change in volume What is the equilibrium constant Kc for the reaction 19 B 9 C 9 16 D 169 Consider the reaction PC15 cgt PCl3g Clzg At a particular temperature 084 moles of PC15 is placed into a 1 L ask At equilibrium 072 moles of PC15 are present Calculate Kc for the reaction 062 B 0020 C 072 D 012 E 50 23 A C 24 A C 25 A C 26 A 27 A 28 A 29 A A Into an empty vessel COClzg is introduced at 10 atm pressure whereupon it dissociates until equilibrium is established according to 2COClzg cgt Cgraphite C02g 2Clzg If x represents the partial pressure of C02g at equilibrium what is the value of the equilibrium constant KP 2x310 7 2x2 B 2x4 10 7 2x2 4x310 7 2x2 D 4x3 10 7 x2 For the reaction AB3g cgt Ag 3Bg what is the equilibrium constant expression if the initial concentration of AB3 is 01 M and the concentration of A is represented by x 3x201x B x4017x3 x4017 3x3 D 27x4017 x A mixture of 060 mol Clzg and 040 mol F2g was allowed to come to equilibrium in a 10007mL ask If 2x represents the molar concentration of ClFg at equilibrium which expression represents the equilibrium constant Clzg F2g 2C1Fg xz 060 7 x040 7 x B 4x2 060 7 x040 7 x 2x 060 7 x040 7 x D 2x2 060 7 x040 7 x The equilibrium constant Kp for the conversion butaneg cgt isobutaneg is 254 at 25 0C If butane at 100 atm is allowed to come to equilibrium the partial pressure of isobutane in the equilibrium mixture will be 0390 atm B 165 atm C 0720 atm D 254 atm Consider the vapor phase reaction 2 HCl cgt H C12 for which Kc 16 at 523 K If 0030 moles of HCl is introduced into a 1 L vessel at 523 K what is the equilibrium concentration of H2 0024 M B 0013 M C 0015 M D 024 M E 00052 M The aqueous reaction HN3 H20 cgt N339 H30 has a value of Kc of 19 x 105 What is the equilibrium concentration of H30 in a solution which was initially 035 M HN3 389 x103912 B 427 x10393 C 708 x10396 D 257 x10393 E 19 x10395 A mixture of 20 mol of COg and 20 mol of H20g was allowed to come to equilibrium in a l L ask at a high temperature If Kc 40 what is the molar concentration of H2g in the equilibrium mixture C0g H20g cgt C02g H2g 10 B 067 C 075 D 13 The equilibrium constant Kc for the reaction 2HIg cgt H2g Izg is 049 Calculate the number ofmoles ofhydrogen produced when one mole of H1 is placed in a 17L vessel 041 B 025 C 029 D 345 A C At 780 C Kp for the reaction NzO4g cgt 2 NOzg is 466 X 108 We introduce 0050 moles of N204 into a 10 L vessel at 780 C and let equilibrium be established The total pressure in the system at equilibrium will be 023 atm B 13 atm C 23 atm D 079 atm In which reaction will an increase in total pressure at constant temperature favor formation of the products CaCO3V G CaOKx COng B 2N0g 0mg cgt 2NOng2 D H2g Clng G 2HC1g COClzg cgt COg Clzg Consider the gaseous reaction 2802 02 cgt 2803 heat Under which conditions is 03 most stable high pressure and high temperature B low pressure and high temperature D high pressure and low temperature low pressure and low temperature Which of the following equilibria would be shifted toward the products by a decrease in the volume of the reaction vessel Hm Ing c 2H1g B NZKg 3Hzg c 2NH3Kg D ZNZOSKg c 4NOng2 0m NH4C1 cgt NH3g HClg For the reaction 2S02g Ozg cgt 2803g AH 7198 kJ carried out at constant volume the concentration of 02 at equilibrium will increase if 02 is added to the system B the temperature of the system is lowered D 03 is added to the system the volume is decreased For the reaction 2S02g Ozg cgt 2803g carried out at constant temperature and volume what is the effect of removing some 03 from a system initially at equilibrium SOZ decreases more than 02 B 80 and 02 remain the same D SOZ increases more than 02 02 and 02 decrease equally The equilibrium PC15g cgt PCl3g Clzg will be shifted to the right by the addition of a catalyst B increase of pressure D removal of C12 removal of PC15 In the reaction heat CaSOg cgt Ca0 8020 which change will cause an increase in the amount of S02g when equilibrium is reestablished increasing the reaction temperature B decreasing the volume of the container D adding some more CaSO3 removing some of the CaOa A C 40 A C E 41 A D 42 A 43 A E 44 A E 45 1 3 5 A Which factor would cause a change in the equilibrium constant Kc for this reaction 2NOClg cgt 2N0g Clzg decreasing the volume of the reaction vessel removing NOg adding NOg B cooling the system D In which gaseous reaction would an increase in pressure at constant temperature have no effect on the relative amounts of the substances present in the equilibrium mixture heat N2 02 cgt 2N0 2C0 02 cgt 2COZ heat 2N0 02 cgt 2NOZ heat B N2 3H2 cgt 2NH3 heat D heat N204 cgt 2NOZ If the system H2g Izg cgt 2HIg is initially at equilibrium the amount of H1 present in the equilibrium mixture at constant temperature could be increased by increasing Hz B adding a catalyst C increasing the pressure 39 E lower1ng 12 increasing the volume Given the exothermic reaction N2g 3H2g cgt 2NH3Kg AH 7921 k At 400 K the equilibrium constant Kc is 053 At 800 K what is the value of the equilibrium constant 053 B gt 053 C lt 053 D dependent on NH3 Consider the gas reaction 2 NH3 cgt N2 3 Hz for which AH 921 1d If when this reaction is at equilibrium Nzg is added the concentration of NH3 will decrease B the concentration of Hz will increase the value of Kc will increase D the reaction will shift to the right the same thing as would have happened if the temperature had been lowered will happen For the endothermic reaction CaCO3s cgt CaOs COzg which of the following actions would shift the equilibrium to form more C02 gas increasing the temperature B decreasing the temperature increasing the pressure D increasing both the pressure and temperature increasing the pressure and decreasing the temperature Consider the following system at equilibrium Nzg 3 Hzg cgt 2 NH3g AHquot 921 k Which of the following changes will shift the equilibrium to the right increasing the temperature 2 Decreasing the temperature increasing the volume 4 Decreasing the volume removing some NH3 6 Adding some NH3 245 B 146 C 235 D 16 E 135 ANSWERS DDADAlCECCDlBEDCBlAEDB ClBBCDBl CBDDClDCBCBlABACBlACEAA 1331 CHAPTER 11 QUESTIONS IGNORE QUESTIONS 3 10 37 onwards Intermolecular Forces 1 A C A A A A A A A The stronger the intermolecular forces in a substance the higher the boiling point B the higher the vapor pressure D the lower the boiling point the smaller the deviation from ideal gas behavior Which substance has the highest boiling point CH4 B He C HF D C12 Which one of these solid substances has a crystal structure containing discrete molecules dry ice B quartz C graphite D silver bromide Which group of substances is arranged in order from the highest to the lowest melting point HFgtH2gtNaF B NaFgtH2gtHF C HFgtNaFgtH2 D NaFgtHFgtH2 Which has the highest boiling point Ar B Kr C Xe D Ne Arrange KCl NH3 and CH4 in order of increasing boiling point CH4ltKC1ltNH3 B NH3ltKC1ltCH4 C CH4ltNH3ltKC1 D NH3ltCH4ltKC1 Which has the highest molar heat of vaporization S8 B H20 C Ar D BaF2 Which of the following properties does not increase with increasing intermolecular forces viscosity B heat of vaporization C melting point D vapor pressure When liquid bromine is cooled to form a solid which of the following types of solid would it form atomic B metallic C molecular D ionic E covalent network Which one of the following substances does not exist in the indicated solid type Na 7 metallic C diamond 7 network covalent graphite 7 network covalent B SiOz molecular NaCl 7 ionic E Neon condenses due to A dipoledipole forces B London dispersion forces C hydrogen bonding D covalent bonding 12 Which of the following molecules will not form hydrogen bonds A H3C CH2 C OH B HF iDI H C H3C CH2 C CH3 D H3C CH2 N CH3 13 Ammonia s unusually high melting point is the result of A dipoledipole forces B London dispersion forces C hydrogen bonding D covalent bonding 14 Octane is a component of fuel used in internal combustion engines The dominant intermolecular forces in octane are A dipoledipole forces B London dispersion forces C hydrogen bonding D covalent bonding 15 In hydrogen iodide are the most important intermolecular forces A dipoledipole forces B London dispersion forces C hydrogen bonding D covalent bonding 16 When the electron cloud of a molecule is easily distorted the molecule has a high A polarity B polarizability C dipole moment D van der Waals radius 17 Which of the following atoms should have the greatest polarizability A F B Br C Po D Pb 18 Which of the following atoms should have the smallest polarizability A Si B s C Te D Bi A C 20 A C 21 A C 22 A C 23 A C 24 A 25 A 26 A 27 A 28 A The strongest intermolecular interactions between pentane C5H12 molecules arise from dipole dipole forces B hydrogen bonding D London dispersion forces covalent bonding The strongest intermolecular interactions between ethyl alcohol CH3CHzOH molecules arise from dipole dipole forces B hydrogen bonding D London dispersion forces covalent bonding The strongest intermolecular interactions between hydrogen sulfide HzS molecules arise from dipole dipole forces B hydrogen bonding D London dispersion forces covalent bonding The strongest intermolecular interactions between hydrogen fluoride HF molecules arise from dipole dipole forces B hydrogen bonding D London dispersion forces covalent bonding Which of the following will form hydrogen bonds between molecules CH3707CH3 CH3CH27F CH33N B CH3CH270H D Which of the following pairs is arranged with the particle of higher polarizability listed first Sez39 S B 1 139 C Mg Mg D Br I Which of the following pairs is arranged with the particle of higher polarizability listed first CCl4 C14 B H20 HZSe C C5H14 C4H10 D NH3 NF3 Which of the following should have the highest boiling point CF4 B CCl4 C CBr4 D C14 Which of the following should have the lowest boiling point C5H12 B C6H14 C C8H18 D CIOHZZ Which of the following has a boiling point which does not fit the general trend NH3 B PH3 C AsH3 D SbH3 29 A B C D Select the pair of compounds in which the substance with the higher vapor pressure at a given temperature is listed first C7H16 Csle B H20 st D CCl4 CBI 4 CH3CH20H CH3707CH3 Which of the following should have the highest surface tension at a given temperature CF4 B 0014 C CBr4 D 014 The energy needed to increase the surface area of a liquid by one square meter is capillary action B surface tension viscosity D cohesion When the adhesive forces between a liquid and the walls of a capillary tube are greater than the cohesive forces within the liquid the liquid level in a capillary tube will rise above the surrounding liquid and the surface in the capillary tube will have a convex meniscus the liquid level in a capillary tube will rise above the surrounding liquid and the surface in the capillary tube will have a concave meniscus the liquid level in a capillary tube will drop below the surrounding liquid and the surface in the capillary tube will have a convex meniscus the liquid level in a capillary tube will drop below the surrounding liquid and the surface in the capillary tube will have a concave meniscus The resistance of a liquid to ow is surface tension B capillary action C viscosity D adhesion Which of the following factors contributes to a low viscosity for a liquid low temperature B hydrogen bonding D spherical molecular shape high molecular weight Which of the following liquid substances would you expect to have the lowest surface tension Pb B CH30CH3 C HOCHzCHZOH D H20 E CH3CH20H Which of the following liquids is likely to have the highest surface tension Brz B C8H18 C CH3OCH3 D Pb E CH3OH Phase Changes 37 How much energy is released When 1000 g of diethylether is cooled from 530 C to 100 C Boiling point 345 C AHvap 35l Jg speci c heat ofliquid 374 Jg K speci c heat ofgas 235 Jg K A 101 N B 131 N C 161 N D 486 N 38 Examine the following phase diagram and identify the feature represented by point A Temperature A melting point B critical point C triple point D sublimation point 39 What are the changes in phase going from points A to B to C to D T A melting vaporization deposition B vaporization freezing sublimation subrnination freezing me ting D freezing sublimation vaporization melting sublimation deposition F110 Answers ACADClCDDCClBCCBAlBDBBClACCAClDAABDlBBCBBl DCA Review Notes Chapter 12 SOLUTIONS homogeneous mixtures consist of SOLUTE and SOLVENT ENERGETICS To make a solution must BREAK interparticles forces in both solute and solvent MAKE new interparticle forces BROKEN ONES CANNOT BE MUCH STRONGER THAN MADE ONES otherwise solution will not form Always get increase in entropy can have both exo and endothermic FORCES Usual ones ionic Hbonding dipoledipole London dispersion when mixing substances that have SAME type of forces When different Solute and Solvent Solution Comments IONIC HBonding or DIPOLEDIPOLE Iondipole Ionic substances water IONIC LONDON DISPERSION Ioninduced dipole Rarely happen DIPOLEDIPOLE London Dipoleinduced dipole SOLUTIONS AND EQUILIBRIUM Unsaturated can add more solute Saturated maximum amount of solute usually in contact with undissolved solute Supersaturated too much solute V unstable Temperature If making solution is endothermic inc temp inc solubility If making solution is exothermic inc temp dec solubility Pressure affects solubility of gases Henry s Law solubility constant kH x pressure QUANTIFYING SOLUTIONS molarity moles solute liters of solution molality moles solute kg of solvent moles fraction ofX moles ofX total moles mass ofX mass ofX total mass X 100 COLLIGATIVE PROPERTIES Depend upon amount of solute concentration Vapor Pressure DECREASES with increasing concentration Raoult39s Law vapor press of solution vapor press of solvent X mole fraction of solvent Boiling Point INCREASES with increasing concentration Each solvent has constant Kbp CHANGE in boiling point Apr Kbp X molality of solution boiling point of solution boiling point of solvent change in boiling point Freezing Point DECREASES with increasing concentration Each solvent has constant Kfp CHANGE in freezing point ATfp Kfp X molality of solution freezing point of solution freezing point of solvent change in freezing point Molar Mass of Solute from Point change Molar mass 1 grams solute X k AT X kg solvent ALL OF ABOVE DEPEND UPON NUMBER OF PARTICLES IONIC SPLIT UP INCREASING NUMBER OF PARTICLES SO INCREASE EFFECT Osmotic Pressure Osmosis is ow of solvent from less concentrated solution to more concentrated one Osmotic pressure is pressure that must be applied to stop process H molarity X R X T R 0082 T in Kelvin Molar Mass ofSolutefrom Osmotic Pressure Molar mass grams solute X R X T V X H CHEM 1332 CHAPTER 17 NOTES De nitions AH AS AG enthalpy heat change at constant pressure 7 can be measured If 7ve exothermic heat given to surroundings good If ve endothermic heat taken from surroundings bad entropy randomness change If ve INCREASE in randomness good If 7ve DECREASE in randomness bad Free energy change 7 relates to ideal work from reaction 7 cannot be measured If 7ve SPONTANEOUS reaction needs no external driving force If ve NONSPONTANEOUS needs external driving force Standard State De ned convention pure liquids or solids gases at 1 atm solutions at l M Laws have not been violated based on experimental evidence lst Law of Thermodynamics Law of Conservation of Energy 2quotd Law of Thermodynamics Spontaneous processes must lead to increase in S of universe 3rd Law of Thermodynamics Only perfect crystal at 0 K has zero entropy Predicting Entropy l Phases g gt 1 gt s 2 Mixtures gt pure substances except when going down in phase 3 Between substances in same phase heavier or more atoms more entropy 4 In reactions in same phase making more molecules more entropy 5 Increase temp increase entropy decrease pressure increase entropy Relationships AH ASquot AG ve at low temp ve at high temp always ve always ve ve at low temp ve at high temp AG very negative ne gative positive very positive Equations COMMON T 0 ALL AHreaction ZAHfproducts 7 ZAHfreactants AHf of elements in natural state 0 ASreamon ZSfproducts 7 ZSfreactants AGreamon ZAGfproducts 7 ZAGfreactants AGf of elements in natural state 0 Can combine reactions to get overall one Overall AS or AH or AG from same combination of individual values ENTROPYRELATED AH TASsurroundings ASuniverse ASreaction ASsurroundings AG TASuniverse DELTA GRELATED AG AH TAS T in K get ALL quantities in either Joules or Kiloj oules AG RTan R 8314 T in K AG in JOULES AG refers to energy change going from all things in standard state to equilibrium AG AG RTln Q AG refers to energy change for ANY stage of reaction Temperature at which reaction goes from spontaneous to nonspontaneous AG 0 T AH AS BOTH EITHER IN JOULES OR KILOJOULES CHEM 1332 CHAPTER 18 NOTES Redox Equations 1 Assign oxidation numbers each atom type gets an oxidation number sum of all oxidation numbers charge elements have oxid number 0 monatomic ions oxid number charge in compounds group 1 has oxid Number 1 group 2 has oxid number 2 unless already assigned H is 1 F is 1 unless already assigned 0 is 2 unless already assigned Cl is 1 if any left unassigned use intelligence and periodic table GEU C933833 Split into half equations a atom that goes UP in oxid number is OXIDIZED b atom that goes DOWN in oxid number is REDUCED c set up oxidized equation with species that contain oxidized atom d set up reduced equation with species that contain reduced atom Balance half equations a BALANCE IMPORTANT ATOMS those that are oxidized or reduced b Include electrons on LEFT in reduced on RIGHT in oxidised c Number of electrons change in oxid number x number of important atoms Determine number of electrons in overall reaction lowest common multiple of electrons in individual half equations Multiply each half equation by number needed to get number in 4 Add up half equations Balance charge using Hl in acidic solution or OH39 in basic solution Balance H s and O s using water If you can t you made a mistake somewhere SPECIES THAT CONTAINS OXIDIZED ATOM IS REDUCING AGENT SPECIES THAT CONTAINS REDUCED ATOM IS OXIDIZING AGENT E l Values Every balanced half equation has an E value 7 potential voltage or EMF when everything in standard state Listed as reduced values E for oxidized E for reduced Bigger the E for the reduced one the better the OXIDIZING AGENT wants to be reduced The more negative the E for the reduced one the better the product is a REDUCING AGENT also related for metals to reactivity For overall reaction E sum of E values for half reaction If E is POSITIVE Reaction is SPONTANEOUS If E is NEGATIVE Reaction is NONSPONTANEOUS Cells Set up redox reaction in different beakers so it is spontaneous GALVANIC or VOLTAIC CELL ANODE electrode at which OXIDATION occurs CATHODE electrode at which REDUCTION occurs Notation Anode reactioanathode reaction means phase change eg Cu2 Zn gt Cu Zn2 Fe Zn gt Fe Zn2 use graphite electrode ANODE Zn gt Zn ANODE Zn gt Zn CATHODE Cu2 gt Cu CATHODE Fe gt Fe Cell is written ZniZnZHCuziCu ZniZnZHFe3 Fe2igraphites Equations we will do these later AGquot nFE n number of electrons in balanced redox equation F 96500 coulombsmole E RT nF1n K or E 00257 nln K E E 00257 n1n Q NERNST EQUATION be sure to get chemical equation right for Q Electrolysis Giving electrons to a reaction Anode gt Ca mde Molten Salt or Solution Cathode electrode hooked to NEGATIVE end of battery REDUCTION Anode electrode hooked to POSITIVE end of battery OXIDATION Molten Salts Cation is reduced to element if possible at cathode Anion is oxidized to element if possible at anode Aqueous Solution Extra possibilities CATHODE either Cation is reduced to element if E less negative than about 710 V Or 2 H20 2e39 gt H 2 OH39 hydrogen gas evolved basic solution will happen if metal is group 1 or group 2 or Al ANODE either Anion is oxidized to element if E less negative than about 714 V Or 2 H20 gt 4 e39 O 4 H oxygen gas evolved acidic solution will happen if anion is uoride or oxy anions with element in high oxidation number STOICHIOMETRY how much of an element gets electrolyzed Charge amps x time IN SECONDS Number of moles of electrons charge 96500 Can use simple stoichiometry stuff from last semester or Moles of element amps x time n x 96500 n number of electrons after balancing i e lowest common multiple of electrons in half equations Arrhenius Bronsted Lowry Lewis Focus on B L Acids HA Acid Base Acid Base Acid Base CHAPTERS 15 ACID BASE CHEMISTRY dissociates to produce H4r in water dissociates to produce OH39 in water proton donor give H304r in water proton acceptor give OH39 in water electron pair acceptor cation or electron de cient electron pair donor anion or contains lone pair Bases B H something HCations Conjugates Acid HA H20 lt gt H304r A39 Base B H20 gt OH39 BHJr Equilibrium For acid For base Ka H30 A39 HA Kb OH39BH 13 Metal hydroxides and oxides Neutral Ncontaining compounds Anions A39 is CONJUGATE BASE of HA BHJr is CONJUGATE ACID of B All concentrations at equilibrium All concentrations at equilibrium The bigger the K the stronger the acid or base Strong Acids all go to H304r Strong Bases all go to OH Group 1 hydroxides oxides Group 2 hydroxides oxides NH239 amide H39 hydride CH339 alkides hydrocarbon anion CH3039 anions from alcohols Factors Affecting Strength Binary acids HnX eg H20 HF HCl Look at X further to the right or further down in periodic table stronger the acid Oxyacz39ds HnXOm e g H 3PO4 H 2SO4 HNO 3 To compare acids If X different more to the right or up in periodic table stronger acid If X same the more 0 stronger the acid Ions in water Anions are basic UNLESS FROM STRONG ACID Cations are acidic UNLESS FROM STRONG BASE Equilibrium constants related to neutral conjugate Anion H20 lt gt OH39 HAnion Kb Kw KaHAnion Kw 1 x 1039 BaseH H20 lt gt H30 Base Ka Kw KbBase Kw 1 x 1039 Polyprotic Acids More than one Hydrogen H3PO4 H2SO4 More than one equilibrium and Ka Ka1 Ka2 etc To get pH use ONLY rst K Kal To get ion concentrations acid from rst K monoanion from rst K dianion Kaz Buffers Solutions whose pH is resistant to change by small amounts of added acid or base Consist of neutral WEAK acid or base TOGETHER with its CONJU GATE Titrations Add acid to base or base to acid Equivalence point when enough mixed to NEUTRALIZE Strong acid strong base pH 7 Strong acid weak base pH lt 7 conjugate ACID left Weak acid strong base pH gt 7 conjugate BASE left Weak acid weak base pH depends on which is stronger Use INDICATORS to tell weak acids whose conjugate base is different color Calculations p means log of pH logH30 pOH log OH39 pKa log Ka PKb 40 Kb pHpOH 14 at 25 0 C Kw H3OOH39 1014 at 25 0C To nd K from pH Equilibrium problem pH gives you quotXquot To nd pH pOH or simply concentrations 1 write all amounts as molarities if mixture new mol old mol X old volume total volume 2 eliminate spectator ions don39t forget CHARGE group 1 cations group 2 cations Cl39 Br39 I39 NO339 HSO439 ClO439 ClO339 3 NEUTRALIZE H304r and OH39 cancel Base or anion and H304r leave CONJU GATE ACID Acid or Hcontaining cation and OH39 leave CONJU GATE BASE 4 If nothing left pH 7 5 Any H304r or OH39 left Use to get pH or pOH directly Must nd equilibrium to work with Neutral weak acid Use equilibrium reaction and Ka to get H30 Watch out for initial conjugate Neutral weak base Use equilibrium reaction and Ka to get OH39 Watch out for initial conjugate Anion React with water to give OH39 and Conj Acid Use Kb Kw KaHAnion for K Cation React with water to give H304r and Conj Base Use Ka Kw KbBase for K 1332 REVIEWS CHAPTER 13 Basic Stuff 1 Consider the reaction 8 A 5 B gt 8 C 6 D If C is increasing at the rate of4 Ms at what rate is B decreasing A 040 Ms B 25 Ms C 40 Ms D 64 Ms E 25 Ms 2 Consider the reaction 5 A 3 B gt 9 C 7 D IfA is being used up at the rate of 15 Ms how quickly is D being made A 7 Ms B 14 Ms C 21 Ms D 107 Ms E 14 Ms 3 If at a particular moment ammonia is formed at a rate of 050 Ms from the reaction N2g H2g gt 2 NH3g what is the rate of disappearance of N2 and that of H2 from the reaction A N2 025 Ms H2 075 Ms B N2 025 Ms H2 025 Ms C N2 025 Ms H2 033 Ms D N2 050 Ms H2 050 Ms E N2 075 Ms H2 050 Ms 4 In the reaction C0 3 H2 gt CH4 H2O which rate expression below is incorrect A ACOAt AH23At B ACH4At AH2OAt C ACOAt AH2OAt D 3AH2At AH2OAt E ACOAt ACH4At Rate Laws 5 The rate law for a chemical reaction is determined by A theoretical calculations B measuring reaction rate as a function of concentration of reacting species C determining the equilibrium constant for the reaction D measuring reaction rates as a function of temperature 6 The rate law for a chemical reaction A can be determined from the stoichiometry of the overall reaction B can be determined from the fastest step of the mechanism C can only be determined by using computer simulation D can be determined by measuring rate as a function of reactant concentration E can be determined by measuring rate a function of temperature 7 The value of the rate constant of a reaction can generally be expected to A be independent of temperature B increase with increasing temperature C decrease with increasing temperature D decrease with increasing temperature only if the reaction is exothermic l 10 A The following question concerns the reaction a A b B gt c C d D for which the reaction rate may be written rate kAquotBm where A is the concentration of A and B is the concentration of B Which of the following statements is true k depends on how long the reaction has been going B k depends on temperature D k depends on the concentration of the products k depends on temperature but never pressure k depends on reactants Some chemical reactions proceed at a rate that is proportional to the concentration of a single reactant Such reactions are called zero order reactions B are called first order reactions are called second order reactions do not occur For a reaction to occur at least two molecules or ions must collide in this case however there is only one reactant The rate law for a first order reaction has the form rate k B rate k A2 C rate k A D rate k A B The rate expression for a second order reaction is rate k A B rate k A2 B C rate k A B D rate k A2 B2 For the reaction H2O2aq 3 I39aq 2 H aq gt 1339aq 2 H20 the rate law is rate kH202I39 The correct description of the order of the reaction is First order with respect to H202 first order with respect to I39 first order with respect to H and second order overall First order with respect to H202 first order with respect to I39 second order with respect to H and first order overall First order with respect to H202 third order with respect to I39 second order with respect to H and sixth order overall First order with respect to H202 first order with respect to 139 zero order with respect to H and second order overall 2A 3D gt products is 1st order in A and 2nd order in D What is the rate law in the form rate kAD B kA12D3 C kA D12 D kA2D E kA12D2 The rate law for the reaction A B gt C D is first order in A and second order in B If A is halved and B is doubled the rate of the reaction will remain the same B be increased by a factor of 4 D be increased by a factor of 2 be increased by a factor of 8 The gasiphase reaction A2 B2 gt 2AB proceeds by collisions between A2 and B2 molecules If the concentrations of both A2 and B2 are doubled the reaction rate will be changed by a factor of 12 B 2 C 3 D 4 E W 16 If a reaction proceeding by the mechanism A B gt C D occurs at a rate x and if the concentrations of A and B are both doubled what will be the new rate of reaction A x B 2x C 4x D 8x E 16x 17 For the reaction between gaseous chlorine and nitric oxide 2N0g Clzg gt 2NOClg doubling the concentration of chlorine doubles the rate of reaction Doubling the concentrations of both reactants increases the rate by a factor of eight The reaction is A rst order in NO rst order in C12 B rst order in NO second order in C12 C second order in NO second order in C12 D second order in NO rst order in C12 18 The reaction 5 A 3 B 2 C gt products has a rate law that is 1St order in A 1St order in B and 2quotd order in C Which of the following changes in concentrations will have NO EFFECT upon the rate A double A double B double C B halve A double B double C C double A halve B double C D double A double B halve C E halve A double B halve C 19 For the reaction A 2B gt ABZ determine the rate law given this data Exp A B Rate 1 023 M 017 M 033 Mh 2 046 M 017 M 067 Mh 3 023 M 051 M 100 Mh A rate k A B B rate k A B2 C rate k A2 B D rate k A2 B2 20 Consider the reaction between CH3Cl and NaOH to give CH3OH and NaCl Calculate the rate law for this reaction given the data Experiment Init CH3C1 Init NaOH Rate Ms 1 036 025 37 2 072 025 74 3 144 050 296 A Rate kCH3Cl2NaOH B Rate kCH3C1 NaOH2 C Rate kCH3C1 D Rate kCH3C12NaOH2 E Rate kCH3C1NaOH 21 The table presents data for the reaction 2Hzg 2N0g gt 2H20g N2g What is the rate law Exp NO HZ Rate 1 60 10 18 2 60 20 36 3 10 60 3 4 20 60 12 A rate kH2NO B rate kH22NO C rate kHz2NO2 D rate kHzNO2 3 22 Calculate the value of the rate constant in question 19 A 012 B 19 C 27 D 84 23 For the reaction A B gt C these data were obtained What is the rate law Exp A B Rate 1 010 M 010 M 0030 Mh 2 010 M 020 M 0120 Mh 3 020 M 020 M 0120 Mh A rate kA B B rate kA2B C rate kA2 D rate kB2 24 Initial rate data for the reaction 2N205g gt 4N02g 02g are as follows What is the rate law Exp N10 1 07 Rate 1 015 M 030 M 46 Ms 2 020 M 060 M 61 Ms 3 020 M 030 M 61 Ms A rate kNZOS B rate kN2051Oz2 C rate kN2052 D rate kN2052Oz 25 The data below were measured for the reaction 2A 2B 2C gt D Calculate the rate law Exp A B C rate Mmin 1 025 020 10 51 2 025 040 20 204 3 025 040 10 204 4 050 020 10 102 A rate kA2B2C2 B rate kA B C2 C rate kAB2C D rate kAB2 E rate kABC Integrated Rate Laws and Half Life 26 The decomposition of diethylether at 504 C is rst order with a halflife of 1570 seconds What fraction of the original sample will remain after 4710 seconds A 116 B 18 C 13 D 16 E 132 27 A rst order reaction has the rate law rate kA The half life of this reaction is A 112 l0g10 B 112 ln 2 C 112 ln 2 D 112 l kA0 E 112 ln 2 X k 28 For the reaction 2 NOBrg gt 2 NOg Brzg the rate law is rate kNOBr2 and the rate constant is 080 1 Ms What is the concentration of NOBr after 22 s if the starting concentration is 0086 M A 71x103911M B 84x1011M C 0086M D 12x103912M E 0034M 29 The reaction of cyclopropane to propene is first order with a rate constant of 54 X 10392 hr391 at 25 C If I start with 0150 M cyclopropane how much will be left after 220 hours 00457M B 0105M C 0127M D 0492M E 0M The halflife for the firstorder decomposition of the radioactive nucleus 241U is 15 seconds If I make 50 g of this nucleus how long will it take until I only have 625 g left 30 seconds B 45 seconds C 60 seconds D 75 seconds E 90 seconds The rate law for the reaction 3 A gt C is rate 436 X 10 2 A2 where k is given as 1Mh What is the half life for the reaction if the initial concentration of A is 0250 M 00109 h B 00629 h C 159 h D 917 h E 436 x102 h 2 N02 gt 2 NO 0 follows second order kinetics At 300 C it takes 100 s for the N02 to drop from 00100 to 000650 M What is the value ofk in 1Ms 0096 B 065 C 081 D 12 E 054 CH3NC gt CH3CN is a first order reaction At 2303 C k 630 X 1041 s4 IfI start with 0001 M CH3NC how much is left after 1000 s 0000533 B 000234 C 000188 D 000427 The value of k for a particular secondorder reaction is 047 1Ms If the initial concentration of the reactant is 025 M how long will it take for the concentration to decrease to 013 molL 79 s B 14 s C 37 s D 17 s Substance A undergoes a first order reaction A gt B with a half life of 20 min at 25 0C If the initial concentration of A in a sample is 16 M what will be the concentration of A after 80 min 040 M B 020 M C 010 M D 0050 M The decomposition of hydrogen per0Xide is a first order reaction with k 106 X 10 3 min l How long will it take for 40 of a sample of hydrogen per0Xide to decompose 755 min B 481 min C 4550 min D 31400 min The decomposition of SOClz is first order If the half life for the reaction is 41 h how long would it take for the concentration of SOClz to drop from 036 M to 0045 M 052h B 14h C 12 h D 33 h Arrhenius Equation A B C D E 41 A A change in temperature from 10 0C to 20 0C is found to double the rate of a given chemical reaction How did this change affect the reacting molecules It doubled their average velocity B It doubled their average energy It doubled the number of collisions per second It doubled the pressure inside the reaction vessel It doubled the proportion of molecules possessing at least the minimum energy required for the reaction How is the activation energy Ea determined from measurements of the rate constants as a function of temperature Plot In K as a function of UT where T is measured in degrees Celsius Plot K as a function of l T where T is measured in degrees Kelvin Plot K as a function of T where T is measured in degrees Kelvin Plot In K as a function of UT where T is measured in degrees Kelvin Plot In K as a function of T where T is measured in degrees Celsius The kinetics of the decomposition of dinitrogen pentoxide are studied at 50 C and 75 C Which of the following statements about these studies is correct The rate at 75 C will be greater than that at 50 C because the activation energy is lower at 75 C The rate at 75 C will be greater than that at 50 C because the number of molecules with enough energy to react increases with temperature The rate at 75 C will be lower than that at 50 C because the molecules with higher speeds do not interact as well as the ones at lower speeds The rate at 75 C will be greater than that at 50 C because the concentration of a gas increases with increasing temperature The rate at 75 C will be greater than that at 50 C because the activation energy is higher The Arrhenius equation k Ae39ERT expresses the relationship between the rate constant k and the energy of activation E The probability that colliding molecules will react increases with increasing energy of activation depends only on the empirical constant A increases with decreasing temperature decreases with increasing energy of activation Dinitrogen tetraoxide N204 decomposes to nitrogen dioxide N02 in a firstorder process If k 25 X 103 391 at 5 C and k 35 X 104 s391 at 25 C what is the activation energy for the decomposition 073 ldmol B 58 kJmol C l401dmol D 5801dmol Mechanism 43 The decomposition of hydrogen peroxide in the presence of iodide ion is believed to occur via the mechanism below In this mechanism Ivaq is 1 H202aq 17011 gt H200 107w 2 H202aq 107w gt H200 02g2 17 A a catalyst B a reactant in the overall reaction C the activated complex D a product of the overall reaction 44 The following mechanism has been proposed for the formation of ethylbenzene Which substance is not an intermediate CH3CH2Br AlBr3 gt AlBr4 CH3CH2 CH3CH2 C5H5 gt C5H5CH2CH3 C5H5CH2CH3 AlBr4 gt AlBr3 HBr C5H5CH2CH3 A AlBr3 B CH3CH2 C AlBr4 D C6H6CH2CH3 45 Consider the reaction 2N02g F2g gt 2N02Fg A proposed mechanism for this reaction is shown below What is the rate law for this mechanism 1 N02 F2 gt NOZF F slow 2 N02 F gt NOZF fast A km B kNO F C kNO 2F D kNO F rate 7 NOWZ rate 7 2H 2 rate 7 2 2 rate 7 2n 1 46 The reaction 2 NOg 02g gt 2 NOzg has an observed rate law rate kNO2Oz Three possible mechanisms could be proposed for this reaction as shown MECHANISM I Second step slow MECHANISM II First step slow 1 N0g N0g a N202g 1 ma N0g a N202g 2 mm 02g 7 2 N02g 2 mm 02g 7 2 N02g MECHANISM III One step reaction 2 NOg Ozg gt 2 NOzg Which of these mechanisms is the most likely A I only B II only C III only D I and III E II and III 47 Consider the following mechanism of the oxidation of bromide ions by hydrogen peroxide in acid solution Which of the rate laws in the answers is consistent with this mechanism 1 Ht H202 gt H20OH Fast 2 H20OH Br39 gt HOBr H20 Slow 3 HOBr H Br39 gt Brz H20 Fast A Rate 7 kH202Br39H2 B Rate 7 kH202Br39H C Rate 7 kH20OHBr39 D Rate 7 kH202Br392H2 E Rate 7 kHOBrHBr39HzOZ 7 Reaction Coordinates 48 In a chemical reaction involving the formation of an activated complex transition state which step must always be exothermic A Reactants gt products B Products gt reactants C Reactants gt activated complex D Products gt activated complex E Activated complex gt products 49 Which line in the diagram represents the activation energy for a forward reaction r L A A B B C C D D 50 Which statement concerning the reaction coordinate diagram is true no catalyst present catalyst present A The catalyst decreases the activation energy B The reaction is endothermic C The addition of a catalyst slows this reaction D A and B have lower potential energy than C and D 51 Consider the reaction coordinate shown below and pick the correct statement A the point A represents at set of intermediates B the energy represented by B is the activation energy C there are five steps in the mechanism D the second step is the ratedetermining step E there are four sets of intermediates in the reaction mechanism 9 52 The rate of a reaction in the absence of a catalyst has been measured The rate of the same reaction when catalyzed is 106 times faster The activation energy for this reaction A is 6RT kcalmole B can be calculated from the information above if the temperatures of the reactions are given C is a concept that cannot be applied to chemical reactions D is different in the two cases 53 The addition of a catalyst in a chemical reaction A increases the concentration of products at equilibrium B increases the fraction of reactant molecules with a given kinetic energy C provides an alternate path with a different activation energy D lowers the enthalpy change in the overall reaction 54 Which procedure will lower the activation energy for a particular reaction A subdividing the reactants B increasing the reactant concentrations C increasing the temperature D adding a catalyst ANSWERS BCADBlDBCBClCDCBDlCDDAElDDDADlBCEABlDEAACl BCEDBlDBAABlABEAAlDDCD CHAPTERS 15 FAKE TEST QUESTIONS You might need to know the following K values CH3COOH Ka 18 x 10395 Benzoic Acid Ka 65 x 10395 HNO2 K45x10quot NH3 Kb 18X10395 HF K72x10quot HZS Ka 57x10398 SO Ka 12 X 10392 HS39 Ka 12 X 103913 HCOOH Ka 18 X 10394 HOCl Ka 30 X 10398 SIMPLE ACIDS AND BASES 1 According to the BrnnstediLowry de nition which species can function both as an acid and as a base A Cl39 B so2 C NH D HC0339 E Hgot 2 Which of the following species can function as both a BrnnstedLowry acid and a BrnnstedLowry base in water A HCl B HPO392 C NHZ39 D H30 E NaOH 3 In this reaction CH3COOH H20 lt3 H30 CH3COO39 which substances are bases according to the BrnnstediLowry de nition A CH3COOH and H20 B CH3COOH and CH3COO39 C H20 and CH3COO39 D H30 and CH3COO39 4 In the reaction CN H20 lt3 HCN OH which is an acidibase conjugate pair A H20 and HCN C CN39 and H20 B H20 and OH39 D HCN and OH39 5 Which species is not either an Arrhenius acid or base A HC0339 B NaOH C PHO4 D NH3 6 When we say an ion or a molecule is a base we mean that it has a tendency to A combine with protons B combine with electrons C liberate hydr0Xide ions as the only anions D liberate hydronium ions as the only cations E Form only weakly dissociated salts 7 Select the pair of substances in which an acid is listed followed by its conjugate base A NH3 NH4 B HPOf39 HZPO439 C Hcog39 C02 D CH3COOH CH3COOH2 E H20 Hgot 8 The conjugate acid of HPO4239 is A P205 B P04339 C H2P0439 D H30 E H3P04 Acid Base Strengths 9 Given that HX is a stronger Brnnsted acid than HY in aqueous solution which is true of a l M solution of NaX A It is less basic than a l M solution of NaY B It is more basic than a l M solution of NaY C It yields a neutral solution D It is more concentrated than a l M solution of NaY 10 Which series is the correct order of decreasing acid strength for each group of acids A HZS gt HzTe gt HZSe gt H20 B HClO3 gt HClO4 gt HZSO4 gt HN03 C HClO4 gt HClO3 gt HClO2 gt HClO D HF gt HCl gt HBr gt IH 11 In which pair is the rst member a stronger protonidonating acid than the second A HClOA HClO3 B HZSOS HZSO4 C IHO HBrO D H20 HZS 12 In which pair of acids is the rst member stronger than the second A HClO gt HIO B H3PO4 gt HNO3 C HZSO3 gt HZSO4 D HBrO gt HBrOz 13 Which of the following is the strongest acid A H3PO4 B H3PO3 C H3AsO4 D H3AsO3 E H3PO2 14 Given the data in the Table on the rst page select the strongest base A Cl39 B F39 C CIO39 D HCOO39 E CH3COO39 15 In each of the pairs below predict which acid is stronger i HZS and HZSe ii HNOZ and HN03 iii H2S03 and HC103 A i HZS ii HN03 iii H2S03 B i HZSe ii HN03 iii HC103 C i HZS ii HN03 iii HC103 D i HZSe ii HNOZ iii H2S03 E i HZS ii HNO2 iii HZSO3 16 Which of the following groups of acids isare in the correct order of DECREASING acid strength i In gt HBr gt HCl gt HF ii HBrO gt HBrOz gt HBr03 gt HBrO4 iii HC104 gt HZSO4 gt H3PO4 A iand iii B ionly C ii only D iii only E iand ii A C 18 A D Sim ple 19 A D The amide ion NHZ39 is a stronger base than the hydroxide ion OH39 Which reaction will occur if sodium amide is dissolved in water B D NHZ39 Hp HpMNH 2 NHZ39 HZOAOH39JrNH3 The H O concentration in a 01 M solution of CH3COOH will be more than in NHZ39HZO NHZOHH39 NHZ39 HZO no reaction 01M HF B 01M NaHS C 01M HNO2 02 M CH3COOH E 01 M NaHSO4 pH Calculations A solution that has pH of 8 is very acidic B slightly basic C very basic exactly neutral E slightly acidic The pOH of an aqueous solution is 60 What is the H 1x10398M B 1x10396M C 1x10397M D 8M At 25 C the concentration of OH39 in moles per liter in a solution that has a pH of 8 is 10393 B 10396 C 10397 D 10398 E 1039 The pH of a solution is 5 If the pH of this solution is decreased to 2 by what factor is the concentration of hydrogen ion increased 2 12 B 3 C 10 D 100 E 1000 HCl is a strong acid What is the pH of200 mL of 0002 M HCl 20 B 27 C 34 D 40 What is the pH of a 001 M NaOH solution 103912 B 12 C 712 D 2 E 72 The pH ofa 10 X 10393 M BaOH2 solution at 25 C is 27 B 30 C 110 D 113 When 50 mL of 01 M HCl is mixed with 50 mL of02 M NaOH the HSOT is 005 M B 1 x 10397 M C 01M D 2 x 1039 E 02 M A D A Which has the smallest concentration of OH39 ions 1MNaOH B 00001MNaOH C 1MHC1 D water E 1 M NH3 The OH39 and pH of a 0035 M KOH solution are respectively 0035 M and 146 B 29 x10 M and 1254 0035 M and 1254 E 0035 M and 146 C 29 x10 M and 1254 What is the pH ofa 10 X 10398 M NaOH solution 8 B 6 C 7 D a bit less than 7 E a bit more than 7 What is the pH ofa solution made by mixing 500 mL of 0125 M KOH with 500 mL of 0125 M HCl 63 B 70 C 81 D 58 E 18 More Complex Equilibrium Calculations 31 A C E What is the correct equation for the ion product constant of water H300H391039 B H30XOH3910397 9151039 D H30XOH391039 OH39 915 OH39 1039 H202 At 90 C pure water has a H3OT 1 X 106 What is the value owa at 90 C 1x 10396 B 7 x 1039 C 1x 1039 D 1x 103912 E 7 x 103912 At 75 C Kw 5 X 1039 What is the pH ofneutral water at 75 C 7 B 14 C 665 D 735 E 223 5107 A 020 M solution of the hypothetical weak acid HZ was found to have a pH of eXactly 30 The ionization constant Ka of the acid is 06 B 20 x10 C 10 x10393 D 50 x106 A 010 M C4H9COOH solution has a pH of 259 What is the K21 ofthis acid 66 x 10396 B 26 x 10393 C 66 x 10395 D 26 x 10392 The pH ofa 055 M solution of HBrO is 448 What is the value of K1 for HBrO 20x10399 B 11x10399 C 60X10395 D 33x10395 E 448 A E A D A E What is the pH of a 0020 M solution of HOCl 245 B 245 C 922 D 922 E 461 What is the pH ofa solution which is 010 M in a monoprotic acid HA with K1 10 X 10396 16 B 35 C 50 D 60 The ionization constant ofa weak acid HA is 1 X 105 If 01 mol of the acid is dissolved in water and diluted to exactly one liter what is the pH of the solution 1 B 3 C 5 D 7 Enough water is added to 035 g of benzoic acid C6H5COOH to make 1000 mL of solution What is the pH 19 B 26 C 34 D 42 The dissociation constant for monoprotic acid HX in water is 134 X 104 What is the concentration of X39 ion in a 020 M solution ofHX 52 x103 B 45 x10 C 20 x10 D 64 x10 The dissociation constant for a weak base B in water was found to be 125 X 106 What is the concentration of H in a 32 M solution of B 20X10393M B 16X103911M C 40X10396M D 50X103912M What is the OH39 in a 050 M solution ofNH3aq 5X10391M B 18X10395M C 6X 10393M D 9X10396M 3 x 10393 M Arsenic acid H3AsO4 has K1 values of 25 X 10394 56 X 108 and 3 X 1013 What is the concentration of the HAsO392 dianion in a solution whose initial arsenic acid concentration was 035 M 94 x103 M B 25 x10 M C 88 X10395 M 56 X108 M E 3 x10 HCN has a Ka of 29 X 108 What is the CN39 in 0115 M HCN 29 X108 M B 424 M C 424 X10395 M D 424 X108 M 58 x 10395 M Ion Hydrolysis 46 A 47 A 48 A 49 A 50 A 51 A D A E A B C D E What is the set of products expected from the hydrolysis of CN ion HCN and OH39 B CN39 and H20 C HCN and PF D HCN and H20 Which substance dissolves in water to form an acidic solution KCl B Na3PO4 C NH4C1 D NaZCO3 Which salt reacts with water hydrolyzes to produce a basic solution NaCH3COO B NaN03 C NH4C1 D BaClO42 Which solution has a pH less than 70 1 M CH3NH3C1 B 1 M NaOCl C 1 M KZCO3 D 1 M NaOH What is the pH of a 030 M sodium acetate Na CH3COO solution 26 B 49 C 91 D 114 Of the four following substances which would form basic solutions NH4C1 NaNO3 K2C03 NaF NH4C1 and NaN03 B NaF and K2C03 E K2C03 and NH4C1 C K2C03 only NaF only Calculate the value of Kb for F39 K21 for HF is 72 X 10394 20 x108 B 14 x1011 C 72 x1018 D 72 x10quot 14 x 103910 What is the pH ofa 015 M solution ofKF K21 for HF is 72 X 104 1201 B 584 C 816 D 233 E 916 Sodium hypochlorite NaClO is an active ingredient in some household laundry bleach Given that the K21 ofHClO is 29 X 108 what is the pH ofa 0015 M solution of sodium hypochlorite 94 B 104 C 89 D 99 E 41 What answer best describes the pH of the following 01 M salt solutions a NaF b KBr c KHCOO and d NH4C1 a pH lt 7 b pH gt 7 c pH gt 7 d pH gt 7 a pH gt 7 b pH 7 c pH gt 7 d pH lt 7 a pH lt 7 b pH 7 c pH lt 7 d pH gt 7 a pH 7 b pH 7 c pH gt 7 d pH lt 7 a pH lt 7 b pH lt 7 c pH lt 7 d pH lt 7 Buffers 56 A 57 A D A D Which pair constitutes a buffer in aqueous solution HCl and NaCl B HBr and KBr C NH3 and NH4C1 D HN03 and NH4N03 The addition of a small amount of acid or base will have very little effect on the pH value of a solution containing equal molar concentrations of NH4C1 and NaCl B NaOH and NaCl C NaOH and HCl NH3 and NaCl E CH3COOH and NaCH3COO Which of the following pairs could be used to make a buffer solution NH3 NaCH3COO B NaNO3 NH4C1 C CH3COOH HCl NaOH NaCl E HNO2 NaNOz Which of the following can form buffer systems a HFKF b HClO4KClO4 c Na2S03NaHS03 b and c B a and c C all three D b E a and b What is the pH of a buffer system consisting of 015 M CH3COONa and 010 M CH3COOH 278 B 287 C 556 D 700 E 492 Kb for ammonia is 18 X 105 What is the pH ofa solution prepared by combining 500 mL of 100 M NH3 and 500 mL of 100 M NH4C1 463 B 926 C 474 D 937 E 700 What is the OH39 ofa solution which is 018 M in ammonium ion and 010 M in ammonia 13 x103 B 13 x105 C 10 x103 D 10 x105 The acid HX has an ionization constant ofl X 104 A solution is 01 M in HX and 10 M in the salt NalX39 What is a close approximation of the hydrogen ion concentration 1X10393M B 1X10395M C 2X10395M D 1X10398M A solution is 0100 M in acetic acid and 0100 M in NaCH3COO What is the PF 136 x103 M B 0100 M C 180 x105 M D 0200 M What is the PF ofa solution which is 02 M in NaCH3COO and 01 M in CH3COOH 90 x107 B 36 x106 C 18 x106 D 90 x106 66 What is the pH of a buffer solution containing 010 M KNOZ and 020 M HNOZ A 366 B 305 C 335 D 202 LEWIS ACIDS AND BASES 67 SnCl4 accepts two electron pairs and acts as A a Brnnsted acid B an Arrhenius base C a Lewis acid D a Lewis base 68 Which of these species is most likely to be a Lewis acid and is also least likely to be a Brnnsted acid A NH4 B BF3 C H20 D OH39 69 Which compound functions as a Lewis acid but not as a Brnnsted acid A BCl3 B N13 C HCl D H20 70 According to the Lewis de nition an acid is a species A having a hydrogen ion B donating a pair of electrons C accepting a pair of electrons D accepting a hydrogen ion 71 In the reaction BF3 F39 a BB BF3 is acting as what type of acid A Arrhenius only B BrnnstedLowry only C Lewis only D All three E Arrhenius and BrnnstedLowry Titrations 72 In titrating NH3aq with 01 M HCl the equivalence point in pH units will be A lower than 7 due to hydrolysis of NH4 B lower than 7 due to hydrolysis of Cl39 C higher than 7 due to hydrolysis of NH4 D higher than 7 due to hydrolysis of Cl39 73 When titrating 25 mL of 10 M HNOZ with 20 M NaOH which of the following statements is correct A The pH at the start of the titration will be greater than 7 B The pH at the equivalence point will be equal to 7 C The equivalence point will occur after addition of 25 mL of NaOH D The pH at the equivalence point will be greater than 7 E HNOZ is a strong acid 74 A 250mL sample of 0130 M HCl is mixed with 150 mL of 0240 M ofNaOH The pH ofthe resulting solution will be nearest A 21 B 7 C 119 D 130 A C A C In the titration of 500 mL of 0100 M benzoic acid a monoprotic acid with 500 mL of 0100 M Na0H the properties of the solution at the equivalence point will correspond exactly to the properties of a 0100 M sodium solution B a 00500 M benzoic acid solution D a 00500 M sodium hydroxide solution a 00500 M sodium benzoate solution Which equation best represents the net reaction that occurs when sodium hydroxide and hydrochloric acid solutions are mixed Na HC1 NaCl H B OH39 H30 2HZO D OH39 HC1 H20 Cl39 NaOH H30 2HZO Na Calculate the pH ofa solution formed by mixing 25 mL of 01 M acetic acid with 125 mL of 01 M NaOH 287 B 302 C 474 D 13 Calculate the pH ofa solution formed by mixing 25 mL of 01 M acetic acid with 125 mL of 02 M NaOH 287 B 512 C 521 D 879 What is the resultant pH when 06 moles of NaOH are added to 1 L of 090 M HCOOH solution 100 B 700 C 255 D 405 E 995 250 mL of 010 M C2H5NH2 ethylamine is titrated with 900 mL of015 M HCl Given that the Kb of ethylamine is 65 x 1039 what is the pH of the solution 1108 B 1088 C 1074 D 1055 E 312 What is the pH at the equivalence point for the titration of 300 mL of a 020 M C6H5COOH solution with 030 M KOH Ka ofC5H5COOH 65 x 105 1073 B 863 C 537 D 326 E 700 What is the pH halfway to the equivalence point for the titration of 020 M CH3NH2 with 020 M HC1 Kb ofCHgNHz 44 x 10quot 106 B 34 C 93 D 47 E 70 What is the resultant pH when 20 mL of 030 M HCl is added to a 300 mL sample of 020 M NH3 Kb for NH3 18 x10395 60 B 89 C 113 D 272 E 51 What is the resultant pH when 100 mL of 0950 M NaOH is added to 100 mL of a buffer solution that consists of 010 M CH3COOH and 010 M NaCH3COO K1 for CH3COOH is 18 x 10395 32 B 47 C 108 D 93 E 63 ANSWERS 1 D 2 B 3 C 4 B 5 D 6 A 7 C 8 C 9 A 10 C 11 A 12 A 13 A 14 C 15 B 16 A 17 C 18 B 19 B A OWWWgtOUOUUWTHUOUUWWNW mwmmowuowuogtgtogtmumugt OUUOOUOUgtOOgtWOWUOWUW mmgtw CHEM 1332 CHAPTER 22 Transition elements and inner transition elements each have a common oxidation state for their ions What are they transition and inner transition respectively 2 3 B 3 2 C 2 2 D 3 3 The ground state electronic con guration of Cr2 is Ar4s13d5 B Ar4s23d4 C Ar3d4 D Ar4s13d3 The ground state electronic con guration of Cd2 is Kr5s24d8 B Kr5s24d10 C Kr5s14d9 D Kr4d10 Which of the following atoms has the biggest radius Ti B Cr C Fe D Ni E Zn A certain transition element has the stable oxidation states of 2 4 5 and 6 In which state will the element be most electronegative 2 B 4 C 5 D 6 A certain transition element has the stable oxidation states of 2 3 5 and 6 In which state will the element be most likely to form an ionic bond with chlorine 2 B 4 C 5 D 6 Which of the following transition elements will form an ion with the largest oxidation number chromium Cr Group 6B6 B iron Fe Group 8B8 D manganese Mn Group 7B7 cobalt Co Group 8B9 Which of the following ions is most likely to form colored compounds Sc B Cu C Zn D Cr Which of the following ions is least likely to form colored compounds Mn B Cr5 C Sc3 D Fe Which of the following will be paramagnetic V B Ni C Mn7 D Ti What is the highest possible oxidation state for molybdenum Mo 2 B 4 C 6 D 8 1 A 20 A 21 A C Which of the following will be the strongest oxidizing agent Cr B CrII C CrIII D CrVI Which of the oxidation states of chromium has the largest valencestate electronegativity CrII B CrIII C CrIV D CrVI A certain transition metal complex has the formula MX4Z If the metal ion has a d8 electron con guration what is the shape of the complex octahedral B square planar C tetrahedral D trigonal pyramid Which of the following is considered a bidentate ligand cyanide CN39 B oxalate C204239 D thiocyanate SCN39 nitrite NOz39 A characteristic of ligands is that they are Lewis acids B they are ions D they are Lewis bases they are electron pair acceptors What is the coordination number of cobalt in the complex ion CoenCl439 en ethylene diamine 8 B 2 C 4 D 6 The oxidation and coordination numbers of cobalt in the compound CoNH35ClClz are respectively 2 and 6 B 2 and 8 C 3 and 6 D 3 and 8 In the compound KCoC2042HzO2 where C204239 oxalate the oxidation number and coordination number of cobalt are respectively 1 and 4 B l and 6 C 3 and 4 D 3 and 6 In the compound NienzHzOzSO4 where en ethylene diamine the oxidation number and coordination number of nickel are respectively 2 and 6 B 2 and 4 4 and 6 C 6 and 6 D Give the systematic name for CuNH34Clz dichlorotetraamminecuprateII B copperHammonium chloride D tetraamminecopperII chloride tetraaminocopperII chloride 22 A C 23 A C 24 A C 25 A C 26 A 27 A 28 A C 29 Give the systematic name for CrCO3NH33 triamminechromium carbonate triamminetricarbonylchromium0 chromiumtriaminotricarbonyl B triamminetricarbonylchromate0 D Give the systematic name for CoCl3HZO39 cobaltII chloride monohydrate B aquatrichlorocobaltateH D aquatrichlorocobaltII aquatrichlorocobaltiteI Write the formula for pentaamminechlorocobaltIH chloride CoNH35C1C1 B CoNH35ClClz CoNH35ClC13 D CoNH35ClCl4 Write the formula for J39 39 J39 39 39 quot 39 J39 39 quot III bromide CoCIZenNH3zBr B C0C12enNH3 lerz CoClzenzNH3zBr D CoClzenzNH3 2Brz Write the formula for sodium tetracyanonickelateII NaNiCN4 B NalNiCN4lz C NaleiCN4l D Na4NiCN4 Which of the following could not participate in linkage isomerism NOz39 B NCO39 C CH D NCS39 Which of the following species could exist as isomers CoHzO4C12 B PtenClz D PtNH3Br339 PtNH33C1l According to valence bond theory what would be the set of hybrid orbitals used when a Period 4 transition metal forms a tetrahedral complex dzsp B dspz C dsp3 D sp3 According to Valence Bond theory in the square planar NiCN4239 complex ion the orbital hybridization pattern is sp3 B dspz C dzsp D disp3 The crystal field splitting energy A is larger for tetrahedral complexes than for octahedral complexes depends on the metal but not on the ligand determines the color of a complex is larger for ionic ligands like chloride than for molecular ligands like CO 3 A 40 A 41 A In the spectrochemical series which one of the following ligands has the strongest eld H20 B CN39 C NH3 D OH39 Which of the following ions could exist in either the highspin or lowspin state in an octahedral complex Sc3 B Ni C Mn D Ti Which of the following ions could exist in only the highspin state in an octahedral complex Cr B Co Mn C Fe D In the presence of a strong octahedral ligand eld the number of unpaired electrons in CoIII will be 0 B 2 C 4 D 6 Which of the following octahedral complexes should have the largest crystal field splitting energy CrH20 613 B CrSCN6339 C CrNH3 613 D CrCN 61339 Which of the following ligands is most likely to form a lowspin octahedral complex with ironIII Cl39 B H20 C CO D OH39 Which of the following ligands is most likely to form a high spin octahedral complex with cobaltII CN39 B I39 C N02quot D CO IronIII forms an octahedral complex with the ligand CN39 How many unpaired electrons are in the dorbitals of iron 1 B 3 C 5 D 7 In a highspin octahedral complex the number of unpaired electrons in NiII will be 0 B 4 C 2 D 6 If a solution absorbs green light what is its likely color red B Violet C blue orange D yellow E ACDADlABDCBlCDDBClBDCDAlBDCBAlCCADBlCBCBAlDCBAClA CHAPTER 19 Extra Questions c 3 X 108 ms 1amu 166054 x103927 kg 1 Faraday 96500 C General Decay A Alpha decay produces a new nucleus whose than those respectively of the original nucleus atomic number is 2 less and mass number is 2 less atomic number is 1 less and mass number is 2 less atomic number is 2 less and mass number is 4 less atomic number is 2 more and mass number is 4 more atomic number is 2 more and mass number is 2 less In the beta emission ofa species such as 1C the process may be considered as the change of a proton into a neutron B the same mode of decay as electron capture D the change of a neutron into a proton neutrino absorption by the nucleus Which particle if lost from the nucleus will result in no change in the atomic number proton B neutron C alpha particle D beta particle Nuclear Equations 4 A C 5 A A A Which nuclear equation is properly balanced ZHe 13N gt 130 1H 14 0 14 7N 46 gt 80 ZHe iBe gt 12C 1H 13 ZHe iZMg gt iZSi iH D Uranium7234 undergoes spontaneous radioactive decay to give an alpha particle and a new nucleus X What is X 230 90U B 238 238 2ZSTh C 94U D 941311 Which symbol may be used to complete this nuclear reaction Li 1H gt 2 1 1H B Em C fie D iD E iHe In the successive nuclear reactions 2U gt Y Ol Y gt Z j the element Z that is formed is 241 33 B 92U C ZZENp D 23in E 2331311 8 In the nuclear reactionlgB He gt 1N X what is X A proton B electron C neutron D positron 9 When 233111 emits an alpha particle the product is 228 236 236 228 A 90 U B 92 U C as Ra D 88 Ra 10 Complete and balance the equation 239Pu 4He gt 7 1n The missing term is 7 A 242Cm B 235U C 233a D 2 106RhE 2 115 Ag 11 The alpha emission by lead204 results in the product isotope A 204Hg B zoon C zong D 203T1 E 204Bi 12 The reaction 14N gt 14C 1H is responsible for producing 14C in the atmosphere What is the bombarding particle A neutron B gamma C alpha D beta E positron 13 Which of the following reactions represents ssion A 3H 2H gt 4He 111 B 238U 120 gt 246Cf 41n C 11B 4He gt 12C 3H D 233Th gt 233Pa fie E 235U 111 gt 146La 87Br 3 1n Nuclear Stability and Decay Types 14 Which of these nuclides is most likely to be radioactive A 39K B 27 A1 C 1271 D 243 Am 15 A nucleus is most likely to be stable when it has an number of protons and an number of neutrons A odd odd B odd even C even odd D even even 16 What is the expected decay of the radioactive isotope 301 A 301 gt iiAr 113 B 301 gt iiAr 11 C 1301 gt IZK 2a D 301 gt iZAr 17 Beta emission may lead to increased nuclear stability by A decreasing the np ratio B increasing the mass number C decreasing the mass number D decreasing the atomic number 18 If a low mass isotope lies above the band of stability one should predict it would decay by A electron capture B alpha emission C positron emission D beta emission Mass De cit etc 19 The mass ofa proton is 1673 X 103924 g the mass ofa neutron is 1675 X 103924 g the mass ofa 56Fe atom is 9289 X 103923 g What is the nuclear binding energy in J for 56Fe A 257x103916 B 77210398 C 836X10399 D 772x103911 20 When two atoms of 2H are fused to form one atom of 4He the total energy evolved is 383 X 103912 J What is the total change in mass for this reaction A 128X103917g B 426X103926g C 345 X108g D 115 g 21 From the equation 1C 1H gt IZN energy and the values ofthe masses 12C 1200386 amu iH 100813 amu 1N 1300819 amu calculate the energy emitted per molar mass ofN formed in the nuclear reaction in J A 342 X 1011 B 7884 X 1011 C 89601 X 1013 D 90384 X 1013 22 Is it believed that two carbon12 nuclei mass 120000 amu can react in the core ofa supergiant star to form sodium23 mass 22989767 amu and hydrogen1 mass 1007825 Calculate the energy in k released from this reaction for each mole of hydrogen formed A 216x1014 B 21631011 C 216X108 D 216le 23 Calculate the mass defect of 17O in amu per atom The actual mass of a 17O atom is 169991 amu that of an electron is 000055 amu a proton is 10073 amu and a neutron is 10087 amu A 01520 B 01479 C 01420 D 01468 E 01534 24 The mass defect for an isotope was found to be 0410 amuatom Calculate its binding energy in Jmol of atoms A 123 x1023 B 369 x1013 C 123 x1020 D 369 x103 E 123 x 103 Half Lives etc 25 A sample of a radioactive isotope initially contains 20 X 1010 atoms After 16 days 5 X 1010 atoms remain What is the halfilife of the isotope A 4 days B 8 days C 12 days D 16 days 214 26 The halfilife of 83 Bi is 197 min Starting with 103 g of 281 Bi how many grams remain after 591 min A 125x1041 B 333x1041 C 25031041 D 500x104 27 The half life of 2 Fr is 19 minutes How many minutes will it take for a given amount of this substance to decay to 1 8 of its original activity A 8 B 19 C 57 D 152 28 Palladium107 undergoes decay halflife 65 X 105 years to form silver107 How long will it take in years for 0150 moles of Ag 107 to form from 125 moles of Pd107 A 83x105 B 12x105 C 14X107s D 20x107 29 Charcoal found in an old tomb has a carbon14 activity that is 0366 times that of present dry wood Estimate the age of the charcoal given that the halflife of carbon 14 is 5730 years A 831 x 1033y B 377X103y C 361 x 103y D 698X102y E 164 10 y 30 Iron59 is a radioactive isotope with a halflife of 46 days If the initial count rate of a 59Fe sample is 560 countsmin how long will it take for the count rate to drop to 400 countsmin A 222 min B 14111 C 873 min D 329 days E 223 days Answers 1234567 89101112131415161718192021222324252627282930 CBBBBEECDACAEDD BADDB ACCBBA CB AE Also from book 8 10 12 14 38 79c 81c etc 1332 REVIEW CHAPTER 13 Rate of reaction change in concentration chemical change in time At Relative Rates ForreactionaAbB gtcCdD Rate1AA AB lAC lAD aAt bAt cAt dAt Types of Rate Average rate over period of time total change in concentration change in time Instantaneous rate slope of tangent at the given time to a curve of concentration vs time Initial Rate instantaneous rate at time zero Rate Law ALWAYS OF FORM rate kReactant AXReactant By k Rate constant temperature dependent units depend on rest of equation X y exponents or order of reaction Overall order sum of individual orders Determine rate law by measuring rate as starting concentration is varied Plug data into rate law equation gt simultaneous equations divide one by another to eliminate all but one unknown repeat until all exponents are known if necessary plug into one equation to solve for k Integrated Rate Equations First order 111 Alo AM kt Second order 1 l kt Alt Ala t time A0 initial concentration of A At concentration of A after time t Half Life Time for half of reactant to disappear 1 half life half gone 2 halflives 34 gone 3 halflives 78 gone First order tlz ln 2 k concentration independent Second order tlz l kA0 concentration dependent Arrhenius Equation kAeXpEaRT or anlnA7EaRT A frequency factor related to probability and orientation of collisions Ea activation energy always endothermic IN JOULES R 8314Jmol K T temperature in K Find Ea and A by plotting In K against 1 T or use equation ln k1 k2 EaR lTz 7 1 T1 where l and 2 represent k values at different temperatures Reaction Coordinate Diagrams Peaks transition states activated complexes of each step Valleys intermediate Highest peak slowest step Ea energy between reactants and highest peak Mechanisms Reactions occur in steps one or more mechanism 1 each step is balanced chemical equation 2 each step should have one or two reactants more is unlikely collision 3 all steps must add up to the overall equation 4 one step is slowest RATE DETERMINING STEP 5 during mechanism INTERMEDIATES are made then used CATALYSTS are used them made Lower Ea 6 rate law comes directly from rate determining step reactants in RDS are those used in rate law coefficients of reactants in RDS are exponents in rate law if have intermediate in RDS replace by reactants in previous steps that made it 1332 CHAPTER 18 Sample Questions Couple E0 Couple E0 Brz 26 gt 2Br aq 106 V AuCl4 3 gt Au 4Cl 100 V Ag a gt Ag 080 V ngzt 2 gt 2 Hg 079 V Fe3aq e gt Fezaq 077 V Cu2aq 2 gt Cua 034 V Cd2aq 2 gt Cda 040 V Fe 2e gt Fe 044 V ant 26 gt Zn 076 V Mn2 26 gt Mn 118 V A13 3e gt A1 166 V Mgzt 2e gt Mg 237 V REDOX 1 What is the oxidation number of phosphorus in H3POZ A 1 B 2 C 3 D 4 2 In the ion H2P2072 the oxidation number for P is A 2 B 4 C 5 D 6 3 In which acid is the oxidation number of phosphorus lowest A H4P207 B H3130 C PH3 D mm 4 Identify the pair of compounds haVing underlined atoms with the same oxidation number A H2 O4 and HmO C H9103 and HMO B H9104 and H2g207 D HMO3 and H3304 5 The oxidation number of C1 in KClOz is A 1 B 1 C 3 D 5 6 What is the oxidation number of sulfur in 205 A 2 B 5 C 6 D 10 7 Which statement is true for the reaction Fe Cu2aq gt Cu F62aq A Cu is oxidized B Cu gains in oxidation state C Cult is reduced D Fe is reduced 8 Consider the reaction 2Fe3aq 217mg gt 2Fe2aq 120q Which statement is true A Fe3 is oxidized B Fe3 increases in oxidation number C Fe3 is reduced D I is reduced 1 In the chemical reaction Zna CUSO4aq gt ZHSO4aq Cu metallic zinc is reduced sulfate ion is the oxidizing agent metallic zinc is the reducing agent B copper ion is oxidized D Which substance behaves as the oxidizing agent in Pb PbOz 2HZSO4 gt 2PbSO4 2HZO Pb B PbSO4 C Pbo2 D st04 In the process of oxidizing Fe to Fe Cr2072 is reduced to Cr3 How many moles of Fe are oxidized by one mole of Cr2072 l B 3 C 4 D 6 Given the unbalanced equation ClO3 N02 gt C1 NO3 How many moles of N02 will react with 1 mol of C103 1 B 2 C 3 D 4 Balance this equation Fe MnO4 gt Fe3 MnOz in basic solution The sum of the total number of moles on the left side of the balanced equation is 7 mol B 6 mol C 5 mol D 4 mol Balance the equation for this reaction carried out in a basic solution CrO42 HSnOz gt HSnO3 CrOz The coefficient of HSnOz will be 1 B 2 C 3 D 5 What is the coefficient of Br when this equation is completed and balanced using the smallest integer coefficients Brag MnO4 aq gt Brz Mn2aq acidic solution 1 B 2 C 5 D 10 In acidic aqueous solution MnO4 reacts with Fe to give Mn and Fe Complete and balance the equation What is the coefficient of Felt in the overall net ionic equation 1 B 4 C 5 D 8 Complete and balance the equation assuming the reaction is carried out in basic aqueous solution Mn047aq SZYaq gt MnOza Sn What is the coef cient for water 1 B 8 C 3 D 4 In acidic aqueous solution Cr2072 reacts with HZS to give Sc and Cr3aq When the equation is balanced the coefficient of the Haq in the overall net ionic equation is 4 B 6 C 8 D 14 19 Balance C1047 Fezf gt ClOf Fe3 in acidic solution The coefficient of Hf ions is A 16 B 10 C 8 D 6 E 4 20 Balance the equation for this reaction Cr2072 H8037 gt Cr3f 0427 in acidic solution What number appears before H20 A 1 B 4 C 7 D 10 E 1 1 21 Balance the ionic equation for this reaction MnO4 H202 gt Mn 02 in acidic solution What is the coef cient for H202 A 1 B 2 C 5 D 7 E 8 22 The sum of all coefficients when the equation MnO4 Cl gt Mn2 C12 in acid is balanced is A 21 B 24 C 3 8 D 43 E 51 E values 23 What would be the E0 value in volts for a zincisilver galvanic cell A 004 B 084 C 156 D 236 24 What is the E0 value for a cadmiumisilver voltaic cell A 06 V B 20 V C 12 V D 040 V 25 What is the value of E0 for the spontaneous reaction resulting from a suitable combination of these half Fe3 e7 gt Fe2 A 26 A 27 A 28 A reactions 077 V ngzf 2a gt 2 Hg 079 V 002 V B 0 02 V C 036 V D 156 V E 156 V In a galvanic voltaic cell in which the reaction is Cd Cuzf gt Cu Cdzf and the ions are at unit concentration actiVity the cell potential is 014 V B 040 V C 034 V D 074 V E 037 V What is E0 for this reaction 3Mn 2AuCl4 gt 3Mn 2Au 8Cl 018 V B 218 V C 218 V D 554 V If E for the reaction Brz 2Ce3aq gt 2Br aq 2Ce4 aq is 7055 what is E for Ce4aq e gt Ce3 161 V B 161 V 004 V C 051 V D 29 Using the following halfreactions select the strongest reducing agent HgO H20 2e gt Hg 2 OH39 E 00977 V ZnOH 2 2e gt Zn 2 OH39 E 125 V Ag20 H20 2e gt Ag 2 OH E 0342 V BOH37H 9e gtBH4 3H20 E 0481V A Hg B Zn C Ag D BH4 30 In the cell shown which reaction occurs at the cathode Cus l Cu2aqHAgaqlAgs A Cu2aq 2 e39 gt Cus B Ags gt Agaq e39 C Agaq e39 gt Ags D Cus gt Cu2aq 2 e39 E none of these 31 What is the E ce11 for a Voltaic cell that operates using the half reactions below Cu 2 e39 cgt Cus E 034 V A Sn4 4 e39 cgt Sns E 013 V 068 V B 047 V C 021 V D 021 V E 047 V The iodine clock reaction 208239aq 2 Haq 2 I39aq gt 2 HSO439aq Izaq has E 1587 V and the reduction potential for I 2 e39 gt 2 I39 0536 V What is the reduction potential of 82082 2123 V B 1051V 1051V C 2123V D 0515V GiVen the standard reduction potentials for the following halfreactions Pb2Pb 0 13 V and Ni2Ni 028 V which substance would be oxidized in a Voltaic cell Pb B H C Ni D Pb E Ni Which pair of substances will produce the greatest electromotiVe force when used as electrodes in l M solutions of their ions giVen the reactiVity series NagtZngtFegtPbgtHgtCugtHggtAg A D 35 A D sodium and pure mercury B iron and copper E iron and pure mercury C zinc and hydrogen sodium and hydrogen Using only the metals Mg Al Zn Fe Cu and Ag together with their 1 M salt solutions a Voltaic cell of the highest possible Voltage would be constructed using electrodes of these metals Mg and Ag B Zn and Cu Al and Ag E Mg and Fe C Mg and Al 36 Using the potentials given at the start as well as the fact that Ce4 e39 gt Ce3 is 144 V determine which of the following reactions will be spontaneous under standard conditions A copper reduces silver ions B ferrous ions reduce zinc ions C bromide ions reduce zinc ions D bromine oxidizes ceriumIII ions Cells 37 In every electrolytic and galvanic voltaic cell the anode is that electrode A at which oxidation occurs B which attracts cations C at which electrons are supplied to the solution D at which reduction occurs 38 Which statement is true for the cell as it discharges Zn l Zn2l 0 M H Sn2l0 M l Sn A Oxidation occurs at the tin electrode B Electrons will ow from the tin electrode to the zinc electrode C The concentration of Zn2 will increase D The mass of the tin electrode will decrease 39 In every electrolytic and galvanic cell the cathode is the electrode A which attracts cations B which attracts anions C at which oxidation occurs D at which reduction occurs E at which electrons are removed to the solution 40 Two types of electrochemical cells voltaic and electrolytic can be described Which statement about them is TRUE A current ows directly from the cathode to the anode in an electrolytic cell B the anode in a voltaic cell will gain weight as it runs C oxidation occurs at the cathode in a voltaic cell D the free energy change AG is negative for voltaic cells E the potential of voltaic cells is independent of concentration Spontaneity etc 41 Which reaction is spontaneous in the direction written A 2Ag Cult gt Cu 2Ag B Fe Zn2 gt Fe Zn C 2A1 3Mg2 gt 2Al3 3Mg D 2A1 3Zn2t gt 2Al3 3Zn 42 A spontaneous electrochemical reaction has A AGquot 0 E 0 and K gtgt 1 B AGquot lt 0 E gt 0 and K gt 1 C AG gt0E lt0andKltl D AG gt0E lt0andKgtl E AGquot lt 0 E 0 and K gtgt 1 43 Under which of the following conditions will a cell do the most work A QK lt 1 B QK 1 C E lt 0 D E 0 E QK gt 1 44 Calculate K the equilibrium constant for the reaction Agt aq F62aq gt Ag Fe3 A 100 B 20 C 32 D 10 45 What is the value of the equilibrium constant for the reaction between Sn2 and Fes at 25 C given that Sn2aq Fes cgt Sns Fe2aq E 030 V A 14x101101 B 12x105 C 102 D 86X10396 E 73x1039 46 The value of E for the cell CrslCr3aqlng22aqngl is 159 V What is AGquot for the reaction at 25 A 767 1d B 460 1d C 921 1d D 767 k E 307 k 47 For the halfcell Pb2 2 e39 gt Pb E 0 13 V What is the value of AGquot for the reaction Pbs 2 Haq gt Pb2aq Hzg A 12 1d B 25000 k C 25 1d D 25 k E 12 k 48 Calculate AGquot in 1d for the reaction Ag aq FeZVaq gt Ag Fe3 A 289 B 1517 C 1517 D 289 Nemst Equation 49 Consider the equation Cu2aq Fex gt Cu F62aq The standard potential for this reaction is 078 V What is the potential if the concentrations are 0040 M Cu and 040 M Felt A 072 V B 075 V C 081 V D 084 V 50 Calculate the value ofE for the cell at 25 C CulCu2100 MHAg 00010 M 1 Ag A 011 B 028 C 037 D 055 51 A voltaic cell consists of an MnMn2 electrode Ered 118 V and a FeFe2 electrode Ered 044 V Calculate Felt if ant 0050 M and Ecell 078 v A 024 M B 11 M C 18 M D 080 ME 0040 M 52 The value of E for the reaction Pb2aq Zns gt Zn2aq Pbs is 063 V What is the value of Ecen at 25 C when Zn 000020 M and the concentration of Pb2 10 M A 052v B 162V C 074v D 085V E 041 v 6 53 The value of E for the reaction Zns Cu2aq gt Zn2aq Cus is 110 V What is the value of E for a cell in which 0112 10 x 10395 M and Z1121 10 M A 095 V B 140 V C 125 V D 110 V E 080 V 54 What is the value ofE for the cell AllAl30500 MllFe3 0421 M Fe 10 x 10393 M l Pt A 243 V B 237 V C 249 V D 259 V Electrolysis 55 During electrolysis A positive ions gain electrons at the anode B negative ions lose electrons at the cathode C electrons enter the electrolytic cell at the cathode D ions enter the external or wired circuit and ow from plus to minus E oxidation takes place at the cathode 56 During the electrolysis of an aqueous solution of CuSO4 with inert electrodes A the anode loses mass and the cathode gains mass B the mass of the anode remains the same but the cathode gains mass C the mass of the anode decreases but the mass of the cathode remains constant D the anode and the cathode neither gain nor lose mass E both electrodes gain in mass 57 Aqueous solutions of uorides are difficult to oxidize at the anode of an electrolytic cell because A the aqueous solutions of uorides are nonconducting B it is impossible to nd the proper material from which to build the electrodes C the uorides are not very soluble D in salts the uoride ion has a plus charge E oxygen is released from water in preference to uorine 58 In the electrolysis of dilute H2804 A reduction occurs at the anode B the anode reaction is 2H 26 gt H C the anode reaction is 4OH gt 02 4H 46 D the anode reaction is 2HzO gt 4H 02 46 59 During the electrolysis of an aqueous solution of K2804 the solution around the cathode A becomes acidic B becomes more dilute C becomes basic D remains unchanged E remains neutral 60 What product forms at the anode during the electrolysis of molten lithium iodide A Li1 13 MO C I391 D 12g 61 Five metals are represented by the symbols L M T R and Z When a solution containing all ve ions at 1 M concentration is electrolyzed with a small applied voltage which metal is most likely to be deposited rst on the cathode L gt L 2 076 V R gt R3 3e 7034 V M gt M 2e 044 V T gtth 2e 013 V Z gtZe 7080V A L B M C T D R E Z 62 The halfreaction that occurs at the cathode during the electrolysis of molten sodium bromide is A Brz 2 e39 gt 2 Br39 B 2 Br39 gt Brz 2 e39 C Na gt Nal e39 D 2 H20 2 e39 gt 2 OH39 H2 E Nal e39 gt Na 63 Which requires the smallest voltage for electrolytic deposition given the reactivity order NagtAlgtZngtFegt Cu A Nat B Al3 C Felt D ant E Cu 64 How many coulombs of electricity are required to convert 0340 g of AgNO3 into metallic Ag A 193 B 965 C 193 D 386 65 A solution of CdSO4 is electrolyzed between inert electrodes How many hours must a current of 175 A ow to deposit 118 g of cadmium A 051 B 126 C 322 D 518 66 Chromium metal can be plated from an acidic solution of CrO3 How many grams of chromium will be plated by the passage of 19300 C coulombs A 104 B 519 C 173 D 020 67 What time is required to plate 208 g of copper from Cu2 at a constant current ow of 126 A A 418 min B 128 min C 836 min D 5013 min 68 Nickel is a transition element and has a variable valence Using a nickel salt 2 F faradays plate out 392 g of nickel What ions are in the solution of this salt A Nit B Nizt C Ni3 D Nil3 69 A given amount of electric charge deposits 2159 g of silver from an Ag solution What mass of copper from a Cult solution will be deposited by the same quantity of electric charge A 0635 g B 197 g C 254 g D 127 g 70 How many grams of aluminum are deposited from AlC13 in 30 min by a current of 40 A A 30 g B 67 g C 90 g D 135 g E 270 g 71 One liter of solution contains 320 g of CrN03z What current would be used to deposit all of the chromium in 50 h A 072 A B 14 A C 19 A D 99 A 72 An aqueous copperII sulfate solution is electrolyzed for 45 minutes using a 32 amp current What mass of copper is produced A 56 g B 095 g C 19 g D 28 g E 46 g 73 An aqueous solution of an unknown salt of ruthenium is electrolyzed by a current of 250 amperes passing for 500 minutes Reduction of ruthenium ions deposits 2618 g of Ru metal at the cathode What was the charge on the ruthenium ions in the solution A 3 B 1 C 2 D 3 E 2 74 Calculate the quantity of charge necessary to produce 10 liters of Hzg at STP from the electrolysis of water A 86 x104 C B 17 x104 C C 53 x104 C D 48 x104 C E 37 x 104 C 75 How many grams of Ca metal can be produced by the electrolysis of molten CaBrz using a current of 300 A for 100 hours A 0062 g B 448 g C 112 g D 224 g E 224 g ANSWERS 123 45 678 91011121314151617181920212223242526 ACCDCBC CAC DC BCDC DC DBCDCCAD 27282930313233 3435 36 3738 39 40 41 42 43 4445 46 4748 49 50 CD BCDAC AA AACD DDB ACACDDB B 51525354555657585960616263646566676869707172737475 BCADCBE DCDE EE C CCC CABCDDAE CHAPTER 14 Review General Reactions go backwards as well as forwards use double arrow or a Reach stage when forward rate reverse rate EQUILIBRIUM concentration of all species remain constant At equilibrium rate constant of forward Keq equilibrium constant rate constant of revserse Equilibrium constants KC r0ductscoefficients in balanced equation coefficients in balanced equation reactants ALL CONCENTRATIONS AT EQUILIBRIUM LEAVE OUT SOLIDS s and PURE LIQUIDS l K a ial ressure of r0ductscoef cients in balanced equation 19 13 13 p partial pressure of reactantscoefficients in balanced equation ALL PARTIAL PRESSURES AT EQUILIBRIUM ONLY FOR GASEOUS REAGENTS Kp KcRTAn where An change in number of gas molecules in balanced equation products 7 reactants R 00821 latmmol K T temp in Kelvin Kc is a special case of Q which describes concentration ratio at ANY stage of reaction Q roductscoefficients 1n balanced equation coefficients in balanced equation reactants If Q lt Kc reaction will go to the right forwards to attain equilibrium If Q Kc reaction is at equilibrium If Q gt Kc reaction will go to the left backwards to attain equilibrium NOTE K depends on how chemical equation is written A B cgt C D Equilibrium constant K C D cgt A B then equilibrium constant UK 2 A 2 B cgt 2 C 2 D Equilibrium constant K2 Equilibrium Calculations to nd either K or concentrationspartial pressures at equilibrium 1 Write out BALANCED chemical equation 2 Write out K expression 3 Convert information to Molarity or partial pressures 4 Do you know everything but one thing in the K expression YES 7 solve for unknown NO 7 go to step 5 5 Set up chart 7 four lines a chemical equation b initial concentrations or partial pressures 7 assume zero if not told c change in concentrations or pressures put in X for each species multiply each by coefficient add for reactants for products d equilibrium concentrations or pressures add b and c This gives you ALL equilibrium values in terms of X 6 Do you know K NO 7 must have been told X in question 7 nd it substitute in for ALL equilibrium values plug into K eXpression and solve for K YES 7 question is now essentially solve for X 7 go to step 7 7 Try a simplifying eXpression square root if everything squared etc b can you assume X is really small If K lt initial concentration 20 then X is small So A X or A 7 X EA A is number 7 should simplify equation c if cannot do either of above solve the hard way 8 When you have found X be sure to check which concentrations you need Substitute in the value of X Le Chatelier s Principle If a system at equilibrium is disturbed it will try to recover back to equilibrium a Add product reaction will use up product go to left b Remove product reaction will make more product go to right c Add reactant reaction will use up reactant go to right d Remove reactant reaction will make more reactant go to left For heat changes eXothermic reaction heat is product endothermic reaction heat is reactant apply a through d above e Add catalyst no change to equilibrium just gets there faster REACTIONS INVOLVING AT LEAST ONE GAS ONLY f Increase pressure decrease volume reaction goes to side with FEWER GAS molecules g Decrease pressure increase volume reaction goes to side with MORE GAS molecules h Add inert gas no change to equilibrium 1332 CHAPTER 17 Sample Problems Important Data Compound AHf S AGf kJmol Jmol K kJmol S02g 301 8030 372 NOg 211 867 N02 g 240 518 NOC1g 264 663 N20g 220 1036 Cr 5 2377 02 g 205138 Cr 203 CH4 7487 1861 5081 H20 2418 1888 2286 C02 3935 2137 3944 H2 0 1307 0 C3H8 245 Predicting Entropy 1 Which change is likely to be accompanied by the greatest increase in entropy A N2 3H2 gt 2NH3 13 AgW l t CHM gt AgClS C C025 gt C02g D H20g gt H200 2 Under which conditions does nitrogen have the largest entropy per mole A Nzs at 50 K and 1 atm B Nz1 at 70 K and 1 atm C Nzg at 80 K and 1 atm D Nzg at 80 K and 05 atm 3 In which process is entropy decreased A dissolving sugar in water B expanding a gas C evaporating a liquid D freezing water 4 Which reaction has the largest positive entropy change per mole of product formed A 85 3Fzg gt SF5g B SOzg NazOs gt Na2S03s C Fe3aq SCN39aq gt FeSCN2aq D H20l gt H20g 5 Which pair of the following has the member with the greater molar entropy listed rst ACOg5002g B NaClSNaCIaq C HzSgHzSaq D LiSanS 6 For each pair of substances at the same temperature choose the one with the HIGHER entropy I i 121 ii 12g H i Pcmg ii P015g 111 i Mngs ii BaIzs IV i 2 moles of NOzg ii 1 mole of NzO4g A ii ii ii i B i ii ii ii C ii ii ii ii D i ii i ii E ii i ii i 7 Dissolving crystalline ammonium chloride in water lowers the temperature of the solution so for this process A AH is negative and AS is positive B AH is positive and AS is negative C AH is positive and AS is positive D AH is negative and AS is negative E cannot be determined Entropy Calculations 8 The value of AS for the following reaction 2 NOg Clzg gt 2 NOClg is 7117 JK at 25 C What is the entropy of C12 at this temperature A 106 B 11 C 223 D 223 9 Calculate AS in JK for the reaction 4 Cr 3 02 gt 2 Cr203 A 5481 B l477 C 1477 D 5481 General AG 10 Vaporization of a liquid is an example of a process for which A AH AS and AG are positive at all temperatures B AH and AS are positive C AG is negative at low temperatures positive at high temperatures D AH AS 11 A chemical reaction has a negative AH and negative AS Which statement is correct A The reaction is spontaneous at all temperatures B The reaction is nonspontaneous at all temperatures C The reaction becomes spontaneous as temperature increases D The reaction becomes spontaneous as temperature decreases 12 A reaction is spontaneous at all temperatures if A AH and AS are both positive B AH and AS are both negative C AH is positive and AS is negative D AH is negative and AS is positive 13 Which one of the following statements is true about the equilibrium constant for a reaction if AG0 for the reaction is negative A K0 B Kl C Klt1 D Kgtl 2 14 If K is much less than 1 for a given reaction then A AG will have the same number as K B AG is a large negative number C AG is a large positive number D AG is a small negative number E AG is a small positive number 15 Which of the following is NOT true about AGO A If it is negative for a reaction the reaction is spontaneous B If negative it represents the maximum work available from a reaction C It cannot be measured directly in the lab D If it is large and negative K for the reaction is large and positive E If it is negative AH has to be negative also 16 Which of the following is false A The first law of thermodynamics relates to the conservation of energy B The second law of thermodynamics states that a spontaneous process MUST be accompanied by an increase in the entropy of the universe C The third law of thermodynamics states that only a perfect crystal at 0 K can have zero entropy D The standard state of a species is a defined quantity E Complex processes violate the laws of thermodynamics 17 Which of the following statements are TRUE 1 AG is less than zero for a spontaneous process 11 AG is equal to AH TAS 111 AG is the maximum amount of work that can be obtained from a reaction IV There are no instruments that can measure AG directly A III B I and II C all of them D II and III E I and III 18 A spontaneous reaction is A one that starts right away B always an exothermic reaction C always very fast D none of the above E one that proceeds without continuous input of energy 19 Consider the endothermic reaction C2H4g HzOg gt C2H5OHg When would you expect this reaction to be spontaneous A At all temperatures B Above a certain temperature C below a certain temperature D At no temperature E Not enough information given AG Calculations 20 Calculate AG for the reaction MnOz 2 COg cgt Mns 2 COzg given the following values of AGf Idmol MnOzs 4661 COg 1372 COzg 3944 A 2091 k B 483 k C 18551d D 18551d E 3461kJ 3 21 What is AGO for this reaction 2S02g 0263 gt 2SO3g at 298 K A 7142 k B 7200 k C 7744 k D 142 k 22 Determine the value of AG0 in k for the reaction 2 NOg 02g gt 2 NOzg at 25 C A 698 B 349 C 1047 D 1047 23 What is the value of AH0 in kJ for the reaction N20 N02 gt 3 NO at 25 C A 1562 B 55 C 532 D 1090 24 For the combustion of one mole of liquid methanol AHquot 726 1d Which answer is closest to AGquot for this combustion at 2500 C Molecule CH30H 02 C02 H20 8quot JK mol 1268 2051 2137 1888 A 1161 k B 726 1d C 291 1d D 291 k E 1161 k 25 At what temperature in K will the reaction of methane with water to give hydrogen gas and carbon dioxide become spontaneous A 658 B 683 C 956 D 1229 26 Calculate the temperature at which the following reaction becomes spontaneous Hzg Izg cgt 2 HI given that AS 1659 JK and AH 518 k A 0K B never C 298K D 312K E 325K 27 Iron was originally smelted from ore by heating it with charcoal Calculate the lowest temperature at which this process could be carried out 2 Fe203s 3 Cs gt 4 Fes 3 COzg AHfCOz 3935 ldmol AHf Fe203 8255 kJmol 3 C 57 JK moi 3 Fe 273 JK moi 3 C02 2137 JK moi 3 Fe203 874JK mol A 10612 C B 8426 C C 2646 C D 5695 C E 084 C 28 Coupling of the two reactions below affords the overall reaction Fe3O4s 2 C gt 3 Fes 2 C02 g What is the value of AG0 for this reaction 1 Fe3O4s gt 3 Fes 2 02 g AGO 10142 k 2 023 C gt C02 g AGO 3944 k A 7882 B 7882 C 2254 D 6198 29 Given that AGO for Ba2aq is 75607 for CO3239aq is 75281 and for BaCO3s is 71139 all in kJ calculate Ksp for BaCO3 at 25 C A 586 B 63 x108 C 159 x10399 D 218 x103927 30 Calculate the value of AGquot for a reaction for which Kc 50 X 108 at 25 C A 50 k B 22 1d C 42 k D 25 k E 49500 k 31 Given that AGf for IBr is 13 kJmol calculate K for the reaction at 25 C 1 Brz cgt 2 IBr A 100 B 059 C 13 D 37 X 10396 E 035 32 A particular reaction has an equilibrium constant of 048 at 25 C What is the value of AG0 in kJ A 18 B 42 C 150 D 42 33 Calculate AG0 in 1d for the combustion of propane C3H8 A 5985 B 5985 C 20731 D 20731 34 AH0 1314 k and AGO 912 k for the reaction Cs H20g gt C02g Hzg Calculate AS0 in JK for this reaction at 25 C A 135 B 16 C 16 D 135 ANSWERS 1C2D3D4D5C6A7C8C9A10B11D12D13D14C15E16E17C18E19D 20B21A22A23A24A25C26D27D28C29C30A31E 32A33C34D