GENERAL CHEMISTRY I
GENERAL CHEMISTRY I CHEM 111
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AN ANTHOLOGY OF GENERAL CHEMISTRY QUESTIONS This collection of questions may be of assistance to you in preparing for general chemistry examinations Most of the questions provided are typical of ones used in multiplechoice general chemistry exams Some of these questions may appear on the exams modifications of some of these questions may appear on the exams or questions similar to these may appear on the exams In any case do not assume that only these questions will be used on exams Some of the questions in the Anthology are designed not as exam questions but as aids to your learning of the material The questions are grouped together by topic The answers are provided in a separate section of the chemistrybiochemistry home page Anthology Answers Because the coverage of material differs from one general chemistry course to another eg a topic covered in Chem 111 may not be covered in Chem 110 you should correlate your choice of topics for review in this Anthology with your lecture notes These questions serve only to supplement not replace your lecture notes and your text CONTENTS Topic Scientific Method Metric System and Units Conversions and Conversion Factors Scienti c Exponential Notation Signi cant Figures Physical and Chemical Properties Atomic Structure Elements and Compounds Molecules and Ionic Compounds Polyatomic Ions Naming Ionic Compounds Naming Molecular Compounds Balancing Chemical Equations Electrolytes Acids and Bases WaterInsoluble Compounds Ionic Equations Reactions in Aqueous Solution Other Reactions The Mole Concept Atomic Weights Molecular and Formula Weights Mass Percent Empirical FormulasTheir Calculation Molecular FormulasTheir Calculation Elemental Analysis Mole ConceptChemical Equations StoichiometryChemical Arithmetic Stoichiometry Solutions EnergyForms and Units Enthalpy Calorimetry Thermochemical Equations Hess Law Light Electromagnetic Radiation Quantum Mechanics General Quantum Numbers of the H Atom ManyElectron Atoms Orbital Diagrams Electron Configurations Question Numbers 4 12 13 20 21 23 24 33 34 35 36 38 39 42 43 47 48 51 52 56 57 59 60 63 64 68 69 73 74 76 77 82 83 87 88 89 90 91 92 95 96 104 105 107 108 111 112 113 114 115 116 123 124 134 135 141 142 148 149 153 154 162 163 172 173 176 177 185 186 189 190 205 206 208 209 210 211 222 Atomic and Ionic Radii Ionization EnergiesElectron Aff1nity Ionic Bonding Lewis Dot Structures Lewis Structural Formulas Formal Charges Exceptions to Octet Rule Covalent Bonds Electronegativity Bond Length Strength Order Bond Energy Molecular Geometry Polar Molecules Hybrid Atomic Orbitals on Carbon The Gaseous State Empirical Gas Laws The Ideal Gas Law Gas Mixtures Kinetic Molecular Theory of Gases Comparison of Gases Liquids and Solids Phase Transitions Phase Diagrams Properties of the Liquid State Intermolecular Forces Types of Solids Solutions General Effect of T and P on Solutions Solutions Concentration Units Colligative Properties Colloids 223 228 229 238 239 244 245 246 247 259 260 262 263 266 267 270 271 274 275 276 277 280 281 301 302 305 306 312 313 319 320 333 334 344 345 350 351 353 354 356 357 364 365 368 369 371 372 383 384 392 393 403 404 408 409 417 418 426 427 431 THE SCIENTIFIC METHOD 1 A wellverified explanation of a series of observations is termed A a scientific law B a hypothesis C a theory D a postulate 2 A scientific law is A a statement of fact B a wellverified hypothesis C an eXplanation that enables a scientist to make predictions about natural phenomena D a theory that has been well proven 3 Which statement about a scientific theory is incorrect A A theory is falsifiable B A theory is a wellverified hypothesis C A theory provides an eXplanation for a scientific law D A theory can be proven to be correct given that the appropriate series of eXperiments are performed THE METRIC SYSTEM AND UNITS 4 The SI unit of volume is the liter B cubic meterm3 C milliliter D cubic centimetercm3 gt 5 In the SI system the units for length mass and volume are meter gram and liter meter kilogram and liter meter gram and cubic meter meter kilogram and cubic meter DOW 6 Which combination of units is a correct derived unit in the SI system A kgm2s2 B gm2min2 C gmm2s2 D kgm2min2 7 The prefiX used to indicate 10396 is A milli B kilo C micro D mega 8 The number of mL s in onehalf liter is A 5 B 50 C 500 D 5000 9 The prefix used to indicate 106 is A milli B mega C micro D mini 10 The quantity 0150 meter is specified by A 150 mm B 150 cm C 150 km D 150 nm 11 The quantity 10 cm3 is identical to A 10 L B 10 mL C 10 dL D 10 kL 12 An object has a mass of 982 g and occupies 717 mL Its density equals A 137 gcm3 B 7041 gmL C 137 gm3 D 7071 gmL CONVERSIONS AND CONVERSION FACTORS 13 A temperature of 40 degrees F equals A 40 degrees C B 233 K C both A and B 14 The temperature in Las Cruces is reported to you as 41 C You are more familiar With the Fahrenheit scale Therefore you calculate this temperature to be A 72 F B 106 F C 89 F D 97 F 15 An object has a volume of 00010 m3 Its volume given in cm3 is A 010 B 1000 C 100 D 10 16 A distance is determined to be 1000 um This distance can also be reported as A 00010 m B 0100 cm C 0010 dm D AB and C 17 Given that 254 cm 1 in exact convert 75 miles to kilometers A 47 B 92 C 121 D 109 18 A liquid has a density of 089 gmL Calculate the volume of 10 kg of this liquid A 112 L B 890 mL C 112 mL D 890 L 19 Given that 454 g 1 1b a 500 lb weight can be labeled kg A 110 B 318 C 227 D 895 20 You need to fill your gas tank in Mexico by purchasing 116 gallons of gas You thus Will purchase liters of gas 1 qt9464 L A 110 L B 123 L C 439 L D 464 L SCIENTIFICEXPONENTIAL NOTATION 21 Convert 12345 to scientific notation A 12345 B 12345 C 12345 X 105 D 12345 X 104 22 Convert 12300 to scienti c notation A 12300 B 12300 C 12300 X 104 D 123 X 104 23 Convert 000010 to scientific notation A 1x103 B 10 x103 C 1 x 104 D 10 x104 SIGNIFICANT FIGURES 24 The number of significant figures in 12000 A is 5 B is 4 C is 3 D is 2 E cannot be specified 25 The number of significant figures in 0001 A is 4 B is 3 C is 2 D is 1 E cannot be specified 26 The number of significant figures in 0010 A is 4 B is 3 C is 2 D is 1 E cannot be specified 27 The number of significant figures in 101010 is A6 B5 C4 D3 E 2 For questions 28 32 select the answer to the calculation that contains the correct units and the result to the correct number of significant figures 28 The result of 387 cm X 91 cm is A352 cm2 B 352 cm C 350 cm D 350 cm2 29 The result of 3070 kg X 13 m X 13 m600 s X 600 s is A 001 J B 0014J C 00144 J D 001441 J 30 The result of 09979 091 is A 19079 B 1908 C 191 D 19 31 The result of 1009544 10093 is A 00002 B 000024 C 0000244 D 00002440 32 The result of 36 x 1041222 x 102 is A 43992 x 10 2 B 4399 x 102 C 440 x 102 D 44 x 102 33 The result of10 x 10396 50 x 101120 x 10398 is A 25 x 103974 B 25 x1025 C 25 x1013 D 25 x10393 PHYSICAL AND CHEMICAL PROPERTIES 34 From the following statements select that one or more that specifies a physical property i Sulfur burns in air ii Chlorine is a colored gas iii Ether evaporates at room temperature iv Iron rusts readily in the tropics V Water freezes at 0 C vi Mercury a liquid combines With oxygen a gas to produce a red solid A iiiand vi B ii iii and vi C iiiiivand vi D iivand vi 35 From the list given in Question 34 select one or more chemical properties A i ii and iii B i iv and vi Ci and iv D i and vi ATOMIC STRUCTURE 36 An atom has an atomic number of 12 and a mass number of 24 This atom consists of A 24 protons 24 electrons and 12 neutrons B 12 protons 12 electrons and 24 neutrons C 12 protons 12 electrons and 12 neutrons 37 A given atom has an atomic number of 35 It is an atom of the element A chlorine B bromine C boron D calcium 38 Two atoms have the same Z but differ in A These atoms are A allotropes B isotopes C isomers D chelates ELEMENTS AND COMPOUNDS 39 Most elements are A nonmetals B metalloids C metals D lanthanides 40 From the following list select the elements that are metals i Fe ii S iii Si iv Na V U vi Hg A iiiii B iiv V C iivvvi Diiiivv 41 Which of the following is a nonmetal A Mg B Si C Lu D I 42 Which of the following is an actual compound A S8 B P4 C CO D AgCu MOLECULES AND IONIC COMPOUNDS 43 Which of the following groups include only molecular species A H2g COg CaCO3s LiHs C Sgs AlCl3s BrClg HClg 13 NH3g NaHS H23041 H200 13 HFg H2020 302g SF6g 44 A transfer of electrons occurs when A hydrogen reacts with a nonmetal B two or more nonmetals react with one another C an active metal reacts with a nonmetal D a metalloid reacts with a nonmetal 45 When two nonmetals react they form molecules A never B sometimes C always 46 The subscripts that generally appear in the formula of a molecule A tell us the relative number of each kind of atom present B tell us the exact number of each kind of atom present C A or B depending upon the identity of the molecule 47When calcium ionsCa2 combine with nitride ions N339 the formula of the compound formed is A CaN B Ca2N3 C Ca3N2 POLYATOMIC IONS 48 Which of the following polyatomic ions is named incorrectly A NO3 nitrate B SO4239 sulfate C NH4 ammonium D PO43 phosphite 49 The sodium cation forms sodium nitrate With the anion of oxyacid nitrous acid hydronitric acid nitric acid nitronic acid H DOWgtE 50 The correct formula for the perchlorate ion is A ClO39 B ClO239 C ClO339 D C104 51 The correct formula for the compound formed from aluminum ions and hydroxide ions is A AlOH B AlOH2 C AlOH3 D AlH2 NAMING IONIC COMPOUNDS 52 Select from the following the compound that is incorrectly named A C3NO32 calcium nitrate B FeNO33 iron nitrate C CoS cobaltII sulfide D AlN aluminum nitride 53 The compound having the formula NH4N02 is named ammoniacal nitrite ammonia hydrogen nitrite ammonium nitrate ammonium nitrite Dow 54 The formula of aluminum oxide is A A10 B A102 C A1203 D A1302 55 The formula of copperI phosphate is A Cu3PO4 B Cu3PO42 C CuPO43 D Cu2PO4 56 The correct name of TiO2 is A titanium oxide B titanium dioxide C titaniumIV oxide NAMING MOLECULAR COMPOUNDS 57 The numerical prefix indicating 4 is A tri B tetra C tris D trig 58 The common name of dihydrogen monoxide is A peroxide B ammonia C water 59 Which of the following compounds is named incorrectly A PCl3 phosphorus trichloride B S2Cl2 sulfur chloride C N20 dinitrogen monoxide D P483 tetraphosphorus trisulfide BALANCING CHEMICAL EQUATIONS 60 When the following equation is balanced the sum of all the balancing coefficients is C3H8 02 gt CO2 H20 A 13 B 12 C 11 D 10 61 In balancing Mg3N2 HCl gt MgCl2 NH3 the coefficient must appear in front of HCl A 3 B 6 C 9 D 12 62 When the following equation is balanced the coefficient in front of the Na is Na H2O gt NaOH H2 A 1 B 2 C 3 D 4 63 When the following equation is balanced the sum of the balancing coefficients is Al Fe304 gt Fe A1203 A 20 B 22 C 24 D 26 ELECTROLYTES 64 Which general statement about electrolytes is correct A An electrolyte is a substance that produces ions in aqueous solution B An electrolyte is a substance that in water produces a solution which conducts electricity C An electrolyte may be an ionic or molecular substance D All of the above 65 Which of the following is a weak electrolyte A HCl B HCN C NaOH D HNO3 66 Which of the following is a strong electrolyte A CH3NH2 B HC2H302 C HClO D HClO4 67 Which of the following is a nonelectrolyte A H20 B NaCl C table sugar D CaOH2 68 When NH3 dissolves in H20 the resulting solution contains a limited number of ammonium and hydroxide ions but mostly ammonia molecules This observation enables us to classify ammonia as a A strong electrolyte B weak electrolyte C nonelectrolyte ACIDS AND BASES 69 According to the BronstedLowry definition an acid A is an electronpair donor B is an electronpair acceptor C is a proton donor D is a proton acceptor 70 Which one of the following species is not a strong acid A HF B HCl C H2SO4 D HNO3 71 HClO4 is classified as a strong acid because A it is highly corrosive B it reacts vigorously with HZO C it ionizes essentially completely in aqueous solution D it reacts only with strong bases 72 Identify which of the following is a neutralization reactlon A Cu2aq Zns gt Cus Zn2aq B HClaq NaOHaq gt NaClaq HZOl c CH4g 202g a 002g 2H201 D CaCO3s gt CaOs COzg 73 Which one of the following is a strong base A NH3 B CH3NH2 C NHZOH D KOH WATER INSOLUBLE COMPOUNDS 74 Which one of the following statements about solubility is NOT true A All compounds containing Na NH4 K or Rb are water soluble B All acetates and nitrates are water soluble C With a few exceptions all sulfides carbonates and phosphates are insoluble in water D All chlorides bromides and iodides are water soluble 75 Which one of the following is water soluble A PbC2H3OZ2 B PbS C PbSO4 D PbCO3 76 To form a waterinsoluble substance a solution containing Ca2 ions should be mixed with a solution containing ions A Cl39 B 804239 C NO339 D ClO439 IONIC EQUATIONS 77 Consider the equation PbNO32aq NazSO4aq gt 2NaNO3aq PbSO4s Corresponding to this molecular equation is the ionic equation A Pb2aq 2NO339aq 2Naaq SO4239aq gt 2Naaq 2NO339aq Pb2aq SO4239aq B 2Naaq 2NO339aq gt 2NaNO3aq C Pb2aq 2NO339aq 2Naaq SO4239aq gt 2Naaq 2NO339aq PbSO4s 78 The spectator ions of the reaction of Ques 77 are A Pb2 and SO4239 B Na and NO339 C Pb2 and Na D SO4239 and NO339 79 The net ionic equation corresponding to the reaction of Ques 77 is A Pb2aq SO4239aq gt PbSO4s BNaaq NO339aq gt NaNO3aq C 2Naaq SO4239aq gt Na2SO4aq D Pb2aq 2NO339aq gt PbNO32 aq 80 The net ionic equation corresponding to the reaction HC1aq NaOHaq gt NaC1aq HzO1 is A HC1aq OH39aq gt HZO1 C139aq B Haq NaOHaq gt HZO1 Naaq C Haq OH39aq gt HZO1 81 The net ionic equation corresponding to the reaction HC1aq NH3aq gt NH4C1aq is A Haq NH3aq gt NH4aq B Haq C139aq NH3aq gt NH4aq C139aq C HC1aq NH3aq gt NH4aq C139aq 82 The net ionic equation corresponding to the reaction HCNaq NaOHaq gt NaCNaq HZO1 is A Haq CN39aq Naaq OH39aq gt HZO1 Naaq CN39aq B HCNaq OH39aq gt HzO1 CN39aq C HCNaq NaOHaq gt HzO1 Naaq CN39aq REACTIONS IN AQUEOUS SOLUTION 83 A reaction occurs in aqueous solution When a cation and an anion combine to form A a precipitate B a weak electrolyte C a gas D any one of the above 84 Redox reactions occur in aqueous solution When A a transfer of protons takes place B a transfer of electron pairs occurs C a transfer of one or more electrons occurs 85 When BaC12aq is mixed With NaZSO4aq A no reaction occurs B BaSO4 precipitates C NaCl precipitates D BaSO4 and NaCl precipitate 86 When solid CaCO3 is added to HClaq A nothing happens B COZ gas and liquid HZO form C CaClz precipitates 87 The net ionic equation corresponding to CuSO4aq Zns gt Cus ZnSO4aq is A Cu2aq Zns gt Cus Zn2aq B Cu2aq SO4239aq gt Zn2aq SO4239aq C Cu2aq 2e39 gt Cus OTHER REACTIONS 88 The reaction Cus Ss gt CuSs is an example of A a combustion reaction D a redox reaction B a decomposition reaction E B and D C a combination reaction F C and D 89 When a hydrocarbon burns in excess oxygen the products isare A COz B HzO C heat D A and B E A B and C THE MOLE CONCEPT 90 The mole the chemistry counting unit consists of A 12 units B 6022 units C 6022 X 103923 units D 6022 X 1023 units 91 The mole is defined in terms of the number of atoms of C12 in exactly grams of C12 A 10 B 120 C 1000 D 10000 ATOMIC WEIGHTS 92 The atomic masses provided on the Periodic Table A are relative masses B are based upon the C12 mass as the reference mass C are given in atomic mass units amu D are based upon the proportion of each isotope present in the naturally occurring mixture E all of the above 93 A certain element has 2 isotopes one having a mass of 849118 amu and a fractional abundance of 07215 and the other having a mass of 869092 and a fractional abundance of 02785 The atomic weight of this element is A 859105 amu B 854681 amu C 860025 amu D 857253 amu 94 The average atomic mass of B is 10811 amu It consists of two isotopes B10 10013 amu and B11 11009 amu Calculate the fractional abundance of B10 A 0199 B 0801 C 0204 D 0796 95 The compound ammonia consists of 3 H atoms and 1 N atom per molecule ie NH3 A sample of ammonia contains 7933 g of N and 1712 g of H What is the atomic mass of N relative to that of H A 1390 B 1401 C 4634 D 1396 MOLECULAR AND FORMULA WEIGHTS 96 The molecular weight of C02 is A 4401 amu B 2801 amu C 4401 g D 2801 g 97 The molar mass of C02 is A 4401 amu B 2801 amu C 4401 g D 2801 g 98 The molecular weight of C2H6O is A 3008 amu B 4608 amu C 3008 g D 4608 g 99 The molar mass of C2H6O is A 3008 amu B 4608 amu C3008 g D 4608 g 100 The molecular weight of N2 is A 28014 amu B 28014 g C14007 g D 14007 amu 101 The molecular weight of S3 is A 32066 amu B 25653 amu C 32066 g D 25653 g 102 Which of the following statements is incorrect The formula weight of S is 32066 amu The molar mass of S is 32066 g The formula weight of 02 is 320 g The molar mass of O is 320 g Dom 103 The formula weight of NaNO3 is A 850 amu B 850 g C 690 amu D 690 g 104 The formula weight of Na2B4O7 is A 1852 amu B 20124 amu C 17444 amu D 19781 amu MASS PERCENT 105 The mass percent of oxygen in Na2B4O7 is A 2286 B 5565 C 6152 D 6995 106 A sample of Na2B4O7 contains 03478 g of Na What is the mass of this sample A 1521 g B 1784 g C 2011 g D 1967 g 107 The percent composition of CHZO is C H and O A 372 673 561 B 423 651 512 C 398 634 539 D 400 673 533 EMPIRICAL FORMULASTHEIR CALCULATION 108 A compound contains only N and O A sample of this compound contains 02801 g of N and 01600 g of O What is the empirical formula of this compound A N02 B NO C NZO D N203 109 A compound has the percent composition 800 C and 200 H Its empirical formula is A CH B CH3 C CH2 D CH4 110 Calculate the empirical formula of a compound With the composition 175 Na 397 Cr and 428 O A NaCrO4 B Na2CrO4 C NazCrzO7 D NaCrO3 111 Calculate the empirical formula of a compound having the following composition C 688 H 50 O 262 A C7H602 B C4H3O C C3H3O D C4H302 MOLECULAR FORMULASTHEIR CALCULATION 112 A compound is analyzed and found to have the empirical formula CH2 Its molar mass is found to be 84 gmole Its molecular formula is A C2H4 B C4Hg C C6H12 D CgH16 113 A sample of a carbonhydrogenoxygen compound contains 169 mg of C 0285 mg of H and 227 mg of O Its molecular weight is 600 amu Its molecular formula is A CH20 B C2H402 C C3HgO ELEMENTAL ANALYSIS 114 Combustion analysis is used to obtain the composition of a CH0 compound The carbon content of the sample is obtained from the mass of C02 formed the hydrogen content from the mass of H20 formed The oxygen content of the sample is determined A from the mass of C02 formed B from the mass of H20 formed C from the mass of C02 and of H20 D from the difference between the mass of the sample and the masses of C and H 115 The substance glycol consists of CH and 0 The combustion of 638 mg of glycol in excess 02 produced 906 mg of C02 and 558 mg of H20 Determine the empirical formula of this substance A CH20 B CH30 C C2H50 D C2H502 THE MOLE CONCEPTCHEMICAL EQUATIONS 116 Diethyl ether has the formula C2H520 Calculate the molar mass of this ether A 741 gmol B 451 gmol C 697 gmol D 534 gmol 117 Calculate the mass in grams of one molecule of this ether A 123 B 123 X 103922 C 123 X 103923 D 123 X 1022 118 For a given reaction 0250 mole of this ether is needed How many grams of the ether should be weighed out A 308 B 116 C 185 D 113 119 This ether is a liquid having a density of 0714 g per mL What volume in mL of the liquid is needed to provide 0750 mole A 397 B 778 C 816 D 624 120 A sample of this ether weighs 500 g How many moles of the ether are present A 0921 B 0611 C 0675 D 0877 THE NEXT THREE QUESTIONS RELATE TO THE FOLLOWING EQUATION WHICH IS NOT BALANCED WO3s H2g gt Ws HZOl 121 How many moles of H20 can be produced from 100 mole of WO3 A 100 B 200 C 300 D 400 122 How many moles of H2 are required to react completely With 1 mole of WO3 A 1 B 2 C 3 D 4 123 If 1 mole of H2 is consumed in the reaction how many moles of Ws are produced A 100 B 0667 C 0333 D 133 STOICHIOMETRYCHEMICAL ARITHMETIC THE NEXT EIGHT OUESTIONS RELATE TO THE FOLLOWING EOUATION WHICH IS NOT BALANCED KOzs HzOl gt KOHs 02g 124 How many moles of K02 are needed to react With 4 moles of H20 A 2 B 4 C 6 D 8 125 How many moles of Oz are produced When 0500 moles of KOH are produced A 0375 B 0500 C 0750 D 100 126 How many moles of H20 must react to form 0100 mole of Oz A 0100 B 0667 C 00100 D 00667 127 How many grams of K02 must be provided to react completely With 1800 g of H20 A 1422 B 7109 C 2844 D 2133 128 K02 in the amount of 0500 kg is allowed to react with excess H2O How many kg of KOH are produced A 0500 B 0789 C 0635 D 0395 129 In this reaction 100 g of K02 and 100 g of H20 are used What mass in grams of KOH can be produced A 791 B 200 C 622 D 111 130 For the reaction as described in Ques 129 one reactant was present in excess How much of this reactant was left over A 127 g B 872 g C 563 g D 459 g 131 When 250 g of K02 was allowed to react with excess H2O 157 g of KOH was actually obtained Calculate the percent yield A 100 B 797 C 157 D insufficient information THE NEXT THREE QUESTIONS RELATE TO THE BALANCED EQUATION 3TiO2s 4Cs 6C12g gt 3TiC14g 2CO2g 2COg 132 TiO2 in the amount of 100 g is allowed to react with excess C and C12 The total mass of the products is A 237 g B 274 g C 297 g D cannot be determined 133 How much Cl2 must be provided to react with 100 g of TiO2 in the presence of excess C A 177 g B 886 g C 151 g D 186 g 134 How much of the excess C must react under conditions described in Question 133 A 411g B 200 g C 133 g D 717 g STOICHIOMETRY SOLUTIONS 135 A solution is prepared by dissolving 100 g of NaOH in sufficient H2O to produce 250 mL of solution Calculate the molarity of this solution A 0250 M B 0500 M C 0750 M D 100 M 136 A solution is prepared by dissolving 250 g of ZnSO4 in 1000 g of H20 This solution has a density of 1124 gmL Calculate the molarity of this solution A 124 M B 139 M C 108 M D 167 M 137 A solution in the amount of 200 L is prepared by diluting 280 mL of 180 M H2804 With distilled H20 Calculate the molarity of this solution A 0252 M B 0504 M C 0126 M D 0630 M 138 For a certain reaction 0050 mole of HCl is needed What volume of 0888 M HClaq is needed A 342 mL B 179 mL C 422 mL D 563 mL 139 What volume of 0111 M AlCl3aq is needed to provide 0010 mole of Cl39 A 300 mL B 600 mL C 901 mL D 120 mL 140 For the reaction HClaq NaOHaq gt NaClaq H20l how many mL of 00100 M NaOH are necessary to neutralize the HCl present in 100 mL of 0 0900 M HCl A 900 mL B 900 mL C 090 mL D 900 mL 141 In an acid base titration in Which NaOH neutralized H2804 2NaOHaq HZSO4aq gt 2H20l NaZSO4aq 300 mL of the acid of unknown concentration required 372 mL of 01011 M NaOH for neutralization Calculate the molarity of this sample of H2804aq A 0125 M B 00627 M C 00313 M D 0157 M ENERGY FORMS AND UNITS 142 Which of the following statements about energy is correct A Energy is neither created nor destroyed Energy is either kinetic or potential Energy readily changes from one form to another All of the above new 143 When you start your car electrical energy is converted to mechanical energy chemical energy is converted to electrical energy electrical energy is transferred as heat chemical energy is transferred as heat DOW 144 The first law of thermodynamics states A the energy of the universe is constantly increasing B the energy of the universe is a constant C the energy of the universe is constantly dissipating 145 The 81 unit of energy is A the calorie B the erg C the Joule D the dyne 146 The Joule equals one A gm2s2 B gcm2s2 C kgms D kgmZs2 147 Convert 51 cal to J A 122 kJ B 122 J C 213 kJ D 213 J 148 An object has a mass of 150 g It is moving at a speed of 995 ms Calculate its kinetic energy in J A 7430 J B 743 J C 149 J D 14900 J ENTHALPY 149 Energy can be transferred as either heat or work Enthalpy is the energy transferred as heat in a change occurring at constant volume transferred as work in a change occurring at constant volume transferred as heat in a change occurring at constant pressure transferred as work in a change occurring at constant pressure DOW 150 The symbol for enthalpy is AE BU CS DH EG 151 In an exothermic process the system absorbs energy and AH is positive absorbs energy and AH is negative releases energy and AH is positive UOUUgt releases energy and AH is negative 152 Enthalpy temperature pressure are all state functions but heat and work are not because A heat and work cannot be accurately measured B heat and work are path dependent C heat and work are temperature dependent D heat and work are not measurable quantities 153 Enthalpy equals A Wp B qp C wV D qV CALORIMETRY 154 The quantity associated with the change in temperature of one gram of a substance is termed A heat capacity B molar heat capacity C speci c heat 155 The quantity associated with the change in temperature of an object is termed A heat capacity B molar heat capacity C speci c heat 156 A certain calorimeter has a heat capacity of 192JK For the temperature of the calorimeter to increase from 298 to 327K the calorimeter must absorb J A 192 B 5600 C 5200 D 6100 157 Calculate q when a 100 g sample of Fe speci c heat 0449JgK is cooled from 50 degrees C to 27 degrees C A 103 B 103J C 103 D 103J 158 The speci c heat of water is 4184 JgK Calculate the nal temperature of the mixture when 500 g of water at 358K is added to 1000 g of water at 298K A 318K B 328K C 308K D 338K 159 The speci c heat of Fe is 0449 JgK Calculate the nal temperature of the water and the Fe when 100 g of Fe at 120 degrees C is dropped into 1000 g of water at 25 degrees C A 48 degrees C B 37 degrees C C 26 degrees C D 31 degrees C 160 A calorimeter has a heat capacity of 255JK In an eXperiment the temperature of the calorimeter went from 298K to 301K Calculate q for the calorimeter A 255J B 7651 C 510 D 6251 161 A 105 g sample of benzoic acid C7H602 was burned in a calorimeter having a heat capacity of 180kJoc The temperature of the calorimeter rose 1540C Calculate AH per mole of benzoic acid for this reaction A 3220 H B 3220 H C 264 kJ D 264 kJ 162 A certain hydrocarbon molar mass 780 gmol has a molar heat of combustion of 4100 kJmol A 100 g sample of this hydrocarbon is burned in a calorimeter having a heat capacity of 300 kJOC Calculate AT for the calorimeter A 1750C B 3660C C 3660C D 1750C THERMOCHEMICAL EQUATIONS 163 Which statement is correct about the following thermochemical equation CSzl 302g gt C02g 2SOzg AH 1075 H A This reaction is endothermic B To consume completely 1 mole of C82 1075 H of thermal energy must be absorbed in the reaction C Thermal energy in the amount of 1075 H is released per mole of 802 produced D When 1 mole of C02 is formed 1075 H of thermal energy is released 164 For which of the following chemical changes does the heat of reaction correspond to a heat of formation ANg 3Hltggt a NH3g B H2NNH2g H2g gt 2NH3g C N2g 3H2g gt 2NH3g D 12N2g 32H2g gt NH3g 165 Consider the thermochemical equation CH4g 202g gt C02g 2H20l AH 801kJ What is AH for the reaction of 505 g of CH4g A 253kJ B 253kJ C 801kJ D 801kJ 166 AH for the reaction 12C02g H20l gt 12CH4g 02g is A 801kJ B 801kJ C 401kJ D 401k FOR THE NEXT TWO QUESTIONS YOU WILL NEED TO USE THE STANDARD HEATS OF FORMATION GIVEN IN THE THERMODYNAMICS TABLE OF YOUR TEXT 167 What is the heat of reaction for P4s 50zg gt P4Olos A 2940 B 2940J C 2940kJ D 2940kJ 168 Calculate the heat of reaction for P4010s 6H20l gt 4H3PO4aq A 1132kJ B 498kJ C 1132kJ D 498kJ 169 In the reaction described by 2NOg Ozg gt 2NOzg thermal energy in the amount of 114 k is released Calculate AH per gram of NO A 19kJ B 19kJ C 38kJ D 38kJ 170 Based upon the following thermochemical equation calculate the grams of C3Hgg that must be burnt to provide 255kJ of thermal energy C3Hgg 50zg gt 3COzg 4HZOg AH 2044kJ A 495 g B 550 g C 378 g D 911 g AGAIN USE TABULATED STANDARD HEATS OF FORMATION TO DO THE NEXT TWO QUESTIONS 171 Which of the following liquids has the greatest molar heat of vaporization A CCl4 B CH3OH C CS2 D HCN 172 Using the information provided in this thermochemical equation and tabulated standard heats of formation calculate the standard heat of formation of C4H10g C4H10g 132 Ozg gt 4COZg 5HZO1 AH 2855 H A 148 kJ B 148 kJ C 600 kJ D 600 H HESS LAW 173 Using 1 H2020 gt H201 1202g AH980kJ and 11 2H2g Ozg gt 2H201 AH5716kJ determine AH for H2g 02g gt H2020 4736 kJ D 4736 kJ A 1878 kJ B 1878 H C 174 Given the following data I 2802g 02g gt 2SO3g AH 1967 H II SO3g H20l gt H2804l AH 1301kJ what is the heat of reaction for 2802g 02g 2H20l gt 2HZSO41 A 4569 H B 4569 kJ C 3267 kJ D 3267 H 175 Determine the heat of reaction for C2H50Hl 02g gt CH3COOH1 H20l by using IC2H50H1 302g gt 2C02g 3H20l AH 13669kJ II CH3COOH1 202g gt 2C02g 2H20l AH 8699kJ A 2237 H B 2237 kJ C 497 kJ D 497 kJ 176 Given the following data IN2g 3H2g gt 2NH3g AH 918 H 11 Cs 2H2g gt CH4g AH 749 H 111 H2g 2Cs N2g gt 2HCNg AH 2703 kJ determine the heat of reaction for CH4 NH3g gt HCNg 3H2 A 256 kJ B 256 kJ C 302 H D 302 kJ LIGHT ELECTROMAGNETIC RADIATION 177 The spectrum of light does not include A Xrays B gamma rays C sound waves D microwaves 178 Which of the following wavelengths corresponds to the most energetic light A 750 nm B 125 nm C 7000 nm D 27 nm 179 Which of the following equations specifies the energy of light A E Av B E hv C E 12mv2 D E me2 180 Calculate the wavelength of light having a frequency of 500 X 1014 Hz A 600 nm B 150 nm C 60000 nm D 15000 nm 181 Calculate the frequency of light having a wavelength equal to 626 nm A 188 X 104 Hz B 479 X 1016 Hz C 479 X 1014 Hz D 188 X 107 Hz 182 The quantum of light energy is the A neuron B eXciton C photon D phonon 183 A photon has a frequency of 420 X 1013 Hz Calculate its energy in J A 158 X 103921 J B 278 X 103920 J C 634 X 103920 J D 360 X 10399 J 184 A photon has a wavelength of 155 nm Calculate is energy in J A 780 X 103917 J B 351 X 103914 J C 128 X 10 3918 J D 427 X 103911 J 185 What observations or series of eXperiments directly led to Einstein s quantization of the energy of light A the line spectra of atoms B the photoelectric effect C blackbody radiation D the scattering of alpha particles QUANTUM MECHANICS GENERAL 186 Which of the following statements is FALSE A Energy flows between objects in discrete indivisible amounts rather than continuously B The energy of the atom is restricted to specific amounts C Once the energy of the electron is known so is its eXact position D Light can eXhibit either particle or wave behavior depending upon the system with which it is interacting 187 The concept that the energy of the atom is quantized was based upon a consideration of A blackbody radiation B the line spectra eXhibited by atoms C the stability of the Rutherford nuclear atom D A B and C E B andC 188 The uncertainty principle is due to the scientist A Bohr B Pauli C Schroedinger D Heisenberg E Planck 189 Calculate the deBroglie wavelength of a neutron mass 167 X 103927 kg traveling at a speed of 100 X 105 ms A 397 X 103912m B 252 X 1011m C 429 X 103921m D 511 X 10mm QUANTUM NUMBERS OF THE HYDROGEN ATOM 190 The principle quantum number of the atom is symbolized A ms B m C n D l 191 The allowed values of n are A 01 2 or 3 B 123 C0 12 D 1 2 or 3 192 The allowed values of isare 193 The maXimum allowed value of m is A0 B3 C2 Dl 194 The quantum number that has only two allowed values is A n B l C m D ms 195 The energy of the hydrogen atom is determined solely by the orbital s value of A n B l C m D ms 196 The shape of the orbital depends upon the quantum number An B l C m D n1S 197 The average distance of the electron from the nucleus of the hydrogen atom depends upon A n B l C m D n1S 198 The orientation of the orbital in space depends upon A n B l C ml D ms 199 When equals 2 the orbital is referred to as A an s orbital B a p orbital C a d orbital D an f orbita 200 Which one of the following sets of the four quantum numbers is not allowed n 1 ml ms A 2 1 1 12 B 1 1 1 12 C 2 0 0 12 D 3 2 1 12 201 A shell consists of all orbitals having A the same value of n B the same value of n and l C the same value of n l and ml D the same value of all four quantum numbers 202 The subshell consisting of 5 orbitals of equal energy is the s subshell the p subshell the d subshell the f subshell Dow 203 The number of orbitals in the n 4 shell is A 4 B 9 C 16 D 26 204 An electron releases energy in a transition from the n 4 shell to the n 2 shell of the hydrogen atom How much energy is released A 409 X 103919 J B 349 X 103917 J C 777 X 103915 J D 663 X 103934 J 205 Calculate the wavelength of the photon released in the process of Question 204 A 2600 nm B 484 nm C 17662 nm D 7997 nm MANYELECTRON ATOMS 206 The Pauli exclusion principle states that in the many electron atom A the exact position of any one of the electrons cannot be given B no two electrons can have the same value of the spin quantum number C each electron must have its own unique set of the 4 quantum numbers D all of the above 207 The maXimum number of electrons that can be accommodated in the 4d subshell is A 4 B 6 C 8 D 10 208 The maXimum number of electrons that can be accommodated in the n 3 shell is A 18 B 16 C 14 D 12 ORBITAL DIAGRAMS 209 Which of the following abbreviated orbital diagrams is invalid s p d A T N E B Tl Tl Tl T T T T T C N E Q E D Tl ELLE Tl Tl Tl Tl Tl 210 Which of the following orbital diagrams DOES NOT represent the outermost electrons of an atom in its ground lowest energy state s p d A N TTlTlTlTl B Tl 11 T C Tl TTTl D Tl Tll ELECTRON CONFIGURATIONS 211 Which of the following electron configurations is VALID A ls22s22p73s1 B ls22s22p62d2 C 1s22s22p63s13p6 D 1s12s12p8 212 Which of the following electron configurations represents the ground state of O A 1s22p6 B 1s22s22p23s2 C 1s22s22p22d2 D 1s22s22p4 213 Which of the following represents the ground state of potassium A 1s22s22p63s23p63d1 B 1s22s22p63s23p64s1 C 1s22s22p62d103s1 D 1s22s22p43s23p43d5 214 Which of the following represents the ground state of vanadium A 1s22s22p63s23p63d34s2 B 1s22s22p63s23p63d5 C 1s22s22p43s23p43d9 D 1s22s22p43s23p43d74s2 215 Which of the following represents the ground state of gallium A Ar4s24p1 B Ar3d104s24p1 C Ar4s24p64d5 D Ar4f13 216 Which of the following represents the ground state of Sm samarium A Xe4f66s2 B Xe5d66s2 C Xe4f35d36s2 D Xe4f35d5 217 Which of the following represents the ground state of silver A Kr4d104f1 B Kr4d94f2 C Kr4d95s2 D Kr4d105s1 218 Which of the following represents the ground state of the manganeseII ion A Ar3d5 B Ar3d34s2 C Ar3d44s1 DAr3d54s1 219 Which of the following represents the ground state of the oxide ion A Ne B ls22s22p4 C 2s22p6 D Ar 220 From inspection of their of their orbital diagrams determine which of the following species is paramagnetic A Mg B N339 C Mn D Na 221 The valence electron configuration of an atom is ns2 This atom is A an alkali metal B a halogen C a rare earth D an alkaline earth metal 222 With one exception a noble gas has the outermost electron configuration A ns2np4 B ns2np6 C nld10ns2np6 D nls2np6 ATOMIC AND IONIC RADII 223 The radius of an atom depends upon A n the principle quantum number and Z the atomic number B l the angular momentum quantum number and n C n and A the mass number D l and Z 224 Which of the following Mg Ca Ba or Sr has the largest atomic radius A Mg B Ca C Ba D Sr 225 Which of the following has the smallest atomic radius A Be B N C B D O 226 Which of the following arrangements shows the atoms increasing from smallest to largest A CSltRbltMgltSiltC B RbltCsltSiltMgltC C CltSiltMgltRbltCs D CltMgltRbltSiltCs 227 Which of the following is the largest species A F39 B Cl39 C 0239 D 8239 E N339 F P339 228 Which of the following is the smallest A O2 B O C O D O39 E 0239 IONIZATION ENERGIESELECTRON AFFINITY 229 The first ionization energy of an atom symbol M is described by the equation A Ms energy gt Mg e39 B Ms gt Mg e39 energy C Mg energy gt Mg e39 D Mg gt Mg e39 energy 230 The general trend in the increase in first ionization energies of the representative maingroup elements A is identical to the trend in the increase in their atomic radii B is the reverse of the trend in the increase in their atomic radii C has no correlation at all to the trend in the increase in their atomic radii 231 Which of the following atoms has the greatest first ionization energy A I B Br C Cl D F 232 Which of the following has the lowest first ionization energy A Na B Mg C P D Ar 233 Which of the following arrangements from lowest to highest in first ionization energies is correct A HeltLiltBeltNltNe B LiltBeltNltNeltHe C BeltLiltNltHeltNe D HeltNeltNltBeltLi 234 Which of the following atoms has a third ionization energy several times greater than its second ionization energy A N B C C B D Be THE FOLLOWING QUESTIONS DEAL WITH ELECTRON AFFINITY TWO CONVENTIONS EXIST IN DEFINING THIS QUANTITY THUS BECAUSE OF THE DIFFERENCE IN CONVENTIONS A QUESTION MAY HAVE ALTERNATIVELY CORRECT ANSWERS CHECK YOUR LECTURE NOTES AND TEXT CAREFULLY TO DETERMINE THE CONVENTION BEING USED IN YOUR GENERAL CHEMISTRY COURSE 235 The energy change in which of the following processes constitutes the electron affinity of the species symbolized M A Mg e39 gt M39g B M39g gt Mg e39 C Ms e39 gt M39g D M39s gt Mg e39 236Which generalization about electron affinity is correct A The formation of a stable gaseous anion M39g is accompanied by the release of energy B Nonmetallic atoms have electron affinities of greatest magnitude C The energy change in the gain of an electron by an atom may be a positive or negative quantity depending upon the identity of the atom D all of the above 237 A family or group of elements that do not form stable negative ions is A the alkali metals B the alkaline earth metals C the noble gases D A and B E B and C 238 Which of the following atoms has the electron affinity of greatest magnitude A Cs B C C Se D Cl IONIC BONDING 239 Ionic bonds result from A the transfer of protons from one nonmetal to another B the transfer of electrons from one nonmetal to another C the transfer of electrons from a metal to a nonmetal D the transfer of protons from a nonmetal to a metal 240 All the following except are examples of ionic compounds A NaCl B NaHSO4 C Na2SO4 D H2SO4 241 Ionic compounds A have high melting points B are always solids at normal conditions C conduct electricity only when melted or dissolved in water D all of the above 242 Which of the following equations describes the lattice energy of a substance A Ms energy gt Mg e B MXs energy gt Mg X39g C X39g energy gt Xg e39 D Mg X39g gt MXg energy 243 When a representative maingroup element forms an ion it attains the electronic configuration A alkali metal B noble gas C pseudonoble gas D either B or C 244 Cations formed by representative elements have A a positive charge equal to the group number B a charge equal to the group number 8 C one of several different positive charges D a negative charge equal to the group number LEWIS DOT STRUCTURES 245 The correct Lewis dot structure of the carbon atom is A C B 3 C 396 D 246 The correct Lewis dot structure for N339 is o 3 o 3 o 3 A 39No B 0N0 C D Ne O O LEWIS STRUCTURAL FORMULAS 247 The formula of AlF3 in terms of Lewis dot structures is A A1F39 B A1F3 c Ai z D Alz39F39 03 on 248 A clue to the number of bonds an atom forms is provided by A the atom s position in the periodic table B the number of electrons appearing singly about the atom s Lewis dot structure C the atom s electronegativity D the atom s electron affinity 249 The valid Lewis formula for NH3 is A T B H N H H 0 lil D T 39 HNH 39 39 HuH 39 HNH 250 The correct Lewis formula for PCl3 is 339 B EquotIEI c E I 39F c39 D EI F EI no no no I O 0 CI P CI HI 9 9 251 The correct Lewis formula for F2NNF2 is A F NN F Bi39 rlxi ii Fc F ryry F D F ry rlxlF39 I I o 39 F F szF F F F 252 The correct Lewis formula for H3COCH3 is H H H H I A HCOCH 13 HCOCH I I I H H H H H H I CC I I o 0 c HCOCH D HHHCOCHHH I C I D O O H H 253 A correct Lewis formula for NNO is O O O O C O A NNO 13 3NNOI C NENO O C D D AandB E AandC F BandC 254 The correct Lewis formula for C02 is A oco B C Z c oco Db39c o39 255 Which of the following is a valid Lewis structure for CO A 0 0 B 50792 c Cb D 050 256 Which of the following cannot eXhibit resonance A 802 B 03C CH20 D N0239 257 Which of the following is a valid Lewis structure for HN3 258 A student offers the following Lewis structure for HCN HCN What errors do you observe in the proposed structure A a miscount in the number of valence electrons B a doubly bonded hydrogen C nitrogen without an octet D all of the above 259 At least two valid Lewis structures can be drawn for N20 I I NNo NEN g The true molecular structure is best represented by A Structure I B Structure 11 C A combination of structures I and II FORMAL CHARGES 260 For COC12 the following Lewis structure can be drawn The formal charges on the C the O and both of the Cl atoms are A 1 1 0B 0 0 0 C 2 2 0 D 2 01 261 For COC12 the following Lewis structure can be drawn a o 39 39 ICIC O I O O CI 1 C O The formal charges on the C the O the single bond Cl and the double bond C1 are A 0 0 0 0 B 0 2 0 2 C 0 l 0 1 D 0 1 0 262 Consider the following four Lewis structures I 233 H 232 EI s o39 2C 9 S2 H 39l I III 0 IV 0 I I o s o oso I o o I I H H On the basis of the formal charges calculated for each structure select the correct statement concerning these structures A Structure II is preferable to structure I and structure IV is preferable to structure III B Structure II is preferable to structure I and structure III is preferable to structure IV C Structure I is preferable to structure II and structure III is preferable to structure IV D Structure I is preferable to structure II and structure IV is preferable to structure III EXCEPTIONS TO THE OCTET RULE 263 Exceptions to the octet rule occur because A A bonding atom may not provide sufficient valence electrons B The total number of valence electrons is odd C The d orbitals of a bonded atom are very close in energy to its valence electrons D all of the above 264Which of the following molecules violates the octet rule A N20 B NO C N203 D N2H4 265 Which of the following molecules is electron deficient A CH4 B BH3 C NH3 D H20 266 Which of the following molecules violates the octet rule A CH4 B CCl4 C SF4 D XeF4 E C and D COVALENT BONDS 267 Covalent bonds form When A metals react With nonmetals B metals react With one another C nonmetals including hydrogen react With one another 268 Which statement about covalent bonding is correct A The bond involves the sharing of one or more electron pairs B In the formation of the bond each of the bonded atoms can contribute a single electron C In the formation of the bond one of the bonded atoms can contribute both electrons D The electron pair or pairs can be shared equally by the bonded atoms E The electron pair or pairs can be shared unequally by the bonded atoms F All of the above 269 In the formation of a covalent bond A energy is absorbed B energy is released C energy is either absorbed or released depending upon the identity of the bonding atoms 270 In the formation of the ammonium ion the ammonia molecule donates a pair of electrons to a hydrogen ion to form a covalent bond The bond is lLst described as A a dating bond B a polar bond C a coordinate covalent bond D a nonpolar bond ELECTRONEGATIVITY 271 The quantity termed electronegativity is a quantity A artificially constructed B very easy to measure experimentally C very difficult to measure experimentally D difficult or easy to measure experimentally Use the following data to answer the next three questions Atom Electronegativity H 21 Cs 07 O 35 N 30 P 21 F 40 Cl 30 272 Predict which of the following bonds is the most polar A HO B HP C HCl D HF 273 Predict which of the following is ionic rather than covalent in nature A PN B HCs C FCl D NF 274 Which of the following bonds is are nonpolar A FO B OO C PH D A and B E B and C BOND LENGTH STRENGTH ORDER 275 Bond order refers to A the arrangement of the bonds within a molecule in order of their polarity B the arrangement of the bonds within a molecule in order of their length C the arrangement of the bonds within a molecule in order of their strength D the number of electron pairs shared by the bonded atoms 276 In a series of compounds two nitrogen atoms are bonded to one another In Compound A the N to N bond order is 3 in Compound B it is 2 and in Compound C it is l A The strongest N to N bond is in Compound C B The longest N to N bond is in Compound C C The weakest N to N bond is in Compound A D The N to N bond in Compound B is easier to break than the one in Compound C and harder to break than the one in Compound A BOND ENERGY 277 For which of the following equations does AH represent a bond energy A Cs gt Cg B NaCls gt Nag Cl39g C HCNg gt Hg CNg D Br2l gt 2Brg 278 From the following thermochemical equation determine the average CH bond energy Cg 4Hg gt CH4g AH1662 kJ A 1662 kJ B 416 kJ C 1662 kl D 416 kJ The following data may be of use in answering the next two questions BOND BOND ENERGY kJmol H H 432 C1 Cl 240 H Cl 428 C Cl 327 C C 346 C C 602 279 Estimate AH for CH4g C12g gt CH3Clg HClg A 99 kJ B 99 kJ C 1411 kl D 1411 kJ 280 Estimate AH for H2CCH2g H2g gt H3CCH3g A 191 kJ B 202 kJ C 272 kJ D 144 kJ MOLECULAR GEOMETRY 281 The geometry of a molecule ie its general shape is determined by A the polarity of its bonds B the relative positions of the atomic nuclei C the relative electronegativity of its atoms D the arrangement of the electron pairs about each atom 282 The geometric arrangement that minimizes electron pair repulsions among three electron pairs is A linear B trigonal planar C tetrahedral D pyramidal 283 The geometric arrangement that minimizes electron pair repulsions among four electron pairs is A trigonal planar B trigonal bipyramidal C tetrahedral D octahedral 284 The geometric arrangement that minimizes electron pair repulsions among five electron pairs is A trigonal planar B trigonal bipyramidal C tetrahedral D octahedral 285 The geometric arrangement that minimizes electron pair repulsions among siX electron pairs is A trigonal planar B trigonal bipyramidal C tetrahedral D octahedral 286 According to valenceshell electronpair repulsion theory electronelectron repulsions are greatest between A lone pairs B bonding pairs C lone pairs and bonding pairs 287 According to VSEPR in a group of ve electron pairs if any of the five are lone pairs they are placed above the trigonal plane below the trigonal plane above and below the trigonal plane in the trigonal plane UOUSDgt 288 According to VSEPR theory the BF3 molecule has A trigonal pyramidal geometry B tetrahedral geometry C trigonal planar geometry D bent geometry 289 According to VSEPR CH4 is A pyramidal molecule B tetrahedral molecule octahedral molecule square planar molecule U0 290 According to VSEPR NH3 is pyramidal in shape tetrahedral in shape octahedral in shape trigonal planar in shape U003 291 According to VSEPR PC15 possesses geometry best described as A tetrahedral bipyramid B trigonal bipyramid C a square pyramid D square planar 292 According to VSEPR the geometry of 1339 is A linear B bent C trigonal D pyramidal 293 According to VSEPR the shape of SF6 is A trigonal bipyramid B octahedral C tetradedral D square planar 294 According to VSEPR the shape of CH3Cl is A distorted octahedral B octahedral C tetrahedral D distorted tetrahedral 295 According to VSEPR XeF4 possesses A tetrahedral geometry B square planar geometry C square pyramidal geometry D distorted octahedral geometry 296 According to VSEPR SF4 eXhibits A tetrahedral geometry B seesaw geometry C square planar geometry D square pyramidal geometry 297 According to VSEPR IF5 is shaped like A a trigonal bypyramid B an octahedron C a square pyramid D the letter T 298 According to VSEPR ClF3 possesses a shape A trigonal planar B trigonal pyramidal C T D tetrahedral 299 According to VSEPR C02 is a molecule A linear B bent C trigonal D tetrahedral 300 According to VSEPR H2CO possesses bent geometry trigonal planar geometry distorted trigonal planar geometry distorted tetrahedral geometry com 301 According to VSEPR H2CO possesses A bent geometry B trigonal planar geometry C distorted trigonal planar geometry D distorted tetrahedral geometry POLAR MOLECULES 302 Which of the following statements is incorrect A An electric dipole consists of two partial electrical charges equal in magnitude but opposite in sign and separated by a distance B Whether a molecule is polar or not can be determined eXperimentally C A polar molecule must contain polar bonds D A polar molecule cannot possess a completely symmetric geometry E None of the above 303 Which of the following geometries is not symmetric A trigonal planar B tetrahedral C octahedral D trigonal pyramid 304 Which of the following molecules is polar A BeC12 B C02 C 802 D 1339 305 Which of the following molecules is polar A SiH4 B TeCl4 C XeF4 D AlF439 HYBRID ATOMIC ORBITALS ON CARBON 306 Hybrid atomic orbitals were invented because A the hydrogenlike atomic orbitals were too few in number B the hydrogenlike atomic orbitals could not produce the correct molecular geometry C the energies of the hydrogenlike atomic orbitals did not match the energies of the molecules 307 Which statement about the formation of hybrid atomic orbitals is incorrect A Only orbitals close in energy combine with one another B The number of hybrid orbitals formed always equals the number of hydrogenlike atomic orbitals used C The hybrid orbitals formed have welldefined directional characteristics D None of the above 308 The hybrid orbitals necessary to tetrahedral geometry about the carbon atom are termed A sp hybrids B sp2 hybrids C sp3 hybrids D sp4 hybrids 309 The hybrid orbitals on a doubly bonded carbon are A sp hybrids B sp2 hybrids C sp3 hybrids D sp4 hybrids 310 Which set of hybrid orbitals meets the following description two in number at an angle of 1800 from one another used in the formation of a multiple bond between carbons A sp4 B sp3 C sp2 D sp 311 A carbon atom forms a triple bond by the use of A two sp hybridized atomic orbitals B two sp hybridized atomic orbitals and one 2p hydrogenlike atomic orbital C one sp hybridized atomic orbital and two 2p hydrogenlike atomic orbitals D three sp2 hybridized atomic orbitals 312 When the geometry about a carbon atom is trigonal planar its four bonds consist of A two sigma039 and two pi7c bonds B four sigma bonds C three sigma and one pi bond D four pi bonds THE GASEOUS STATE 313 A gas is A a uid B highly compressible C highly disordered D all of these 314 Which of the following statements is correct A The volume of any gas is the volume of its container B A gas exerts pressure due to collisions of the gaseous molecules against a surface C Under ordinary conditions all true gases behave the same D All of the above 315 Which of the following is not a unit of pressure A atmosphere B millimeters of Hg C Torr D manometers of Hg E psi 316 The device commonly used to measure atmospheric pressure is A a manometer B a sphygmomanometer C a torricelli D a barometer 317 Convert 151 mmHg to Torr A 0199 Torr B 151 Torr C 151 Torr D 199 Torr 318 A gas exerts a pressure of 178 atm This pressure in mmHg is A 1350 B 1070 C 0556 D 178 319 Mercury is commonly used in barometers because of its high density 13596 gcm3 An alcohol having a density of 0899 gcm3 is substituted for mercury Calculate the height of an alcohol column exerting the same pressure as a mercury column 156 mm high A 236 mm B 189 mm C 212 mm D 273 mm EMPIRICAL GAS LAWS 320 The following proportionalities relate to the behavior of gases under ordinary conditions Which proportionality is incorrect A P N T V and n constant B P N V T and n constant C V N T P and n constant D V N n P and T constant 321 A sample of a gas exerts a pressure of 300 Torr and occupies 406 mL Calculate the volume of this gas at the same temperature but at a pressure of 600 Torr A 812 mL B 203 mL C 406 mL D 609 mL 322 A gas sample at 250C occupies 105 mL at a pressure of 698 Torr What volume Will it occupy at this temperature and a pressure of 191 atm A 505 mL B 384 L C 599 mL D 00771 L 323 What external pressure must be supplied to compress 276 L of a gas at 298K and 0878 atm to 200 L at 298K A 484 mmHg B 921 mmHg C 760 mmHg D 878 mmHg 324 A sample of a gas is heated from 250C to 980C The pressure is held constant during the heating process If the original volume of the gas was 222 mL What is its volume after heating A 870 mL B 566 mL C 276 mL D 444 mL 325 A sample of a gas occupies a rigid 100L container and exerts a pressure of 100 atm at 300C What pressure Will it exert after the system is cooled to 200C A 507 Torr B 1140 Torr C 786 Torr D 735 Torr 326 The air Within a hot air balloon is at 180C The atmospheric pressure is 688 mmHg By What percentage does the volume of this hot air balloon increase When the air Within it is heated to 750C A 100 B 417 C 120 D 252 327 Consider a sample of a gas at 100 C occupying 486 mL at 111 atm What volume Will it occupy at 155 atm and 200 C A 274 mL B 441 mL C 696 mL D 861 mL 328 A sample of a gas occupying 225 mL at 33 C and 721 Torr is heated until its volume is 555 mL and its pressure is 701 Torr Calculate its temperature after heating A 840C B 503 C C 790C D 461 C 329 Consider the reaction H2g C12g gt 2HClg According to the results of GayLussac s eXperiments A 100 g of H2 reacts With 100 g of C12 at 298K and 1 atm B 10 molecules of H2 react With 10 molecules of C12 at 298K and 1 atm C 10 moles of H2 react With 10 moles of C12 at 298K and 1 atm D 10 L of H2 react With 10 L of C12 at 298K and 1 atm 330 The concept that equal volumes of gases at the same temperature and pressure contain equal number of molecules is that A of Dalton B of Avogadro C of Boyle D of GayLussac 331 Standard conditions for a gas are A 298K and 706 Torr B 273K and 760 Torr C 273K and 706 Torr D 298K and 760 Torr 332 At STP one mole of any gas occupies A 204 L B 224 L C 204 L D 224 L 333 A 00558mol sample of a gas is at standard temperature and pressure What volume does it occupy A 125 L B 224 L C 181 L D 208 L THE IDEAL GAS LAW 334 The gas constant R that appears in the ideal gas law has the value 008206 L atmmol K Given that 1 Latm 1013 J calculate its numerical value in the units LTorrmol K and in Jmol K A 624 LTorrmol K and 8313 Jmol K B 624 LTorrmol K and 8031 Jmol K C 616 LTorrmol K and 8313 Jmol K D 616 LTorrmol K and 8031 Jmol K 335 A sample of a gas occupies 129 mL at 28 C and exerts a pressure of 682 mmHg How many moles of gas are present A 504 X 10392 B 468 X 10393 C 356 D 631 X 10 393 336 A sample of N2g was generated in the lab At 25 C and 692 Torr its volume was 973 mL How many grams of N2 were produced A 362 X 10393 B 101 X 10391 C 159 X 10393 D 399 X 10391 337 OXygen gas is prepared in the laboratory via 2KClO3s gt 2KCls 302g KClO3 in the amount of 100 g completely decomposed in this manner What volume of 02g at 31 C and 0897 atm was produced A 340 L B 226 L C 0346 L D 155 L 338 For a given reaction 3000 g of N2g is required What volume of N2g at 25 C and 1 atm must be pumped into a reactor to provide the needed N2g A 220 L B 497 L C 262 L D 193 L 339 For a given reaction 3000 g of N2g is required What volume of N2g at 25 C and 1 atm must be pumped into a reactor to provide the needed N2g A 220 L B 497 L C 262 L D 193 L 340 A given number of moles of any gas regardless of its identity occupies a given volume at a specific combination of temperature and pressure Calculate the number of moles of a gas present in 1 L at 25 C and 709 mmHg A 0455 B 00381 C 00345 D 0596 341 Calculate the density of C12g at 25 C and 709 Torr A 270gL B 323gL C 245gL D 195gL 342 Calculate the density of C12g at 37 C and 0592 atm A 263gL B 165gL C 270gL D 192gL 343 Calculate the density of O3g at 25 C and 709 Torr A 270gL B 194gL C 183gL D 249gL 344 Two gases at the same temperature and pressure can differ in their density because A the sample of one gas can contain a greater number of molecules than does the sample of the other gas B the strength of the attractive forces between molecules are different in the two gases C the molecules of the two gases differ in their molecular volumes D the two gases differ in their molecular weight GAS MIXTURES 345 In any mixture of nonreacting gases A the volume of each gas is the volume of the container B each gas is exerting its own pressure C the total pressure is the sum of each gas s individual pressure D the pressure each gas is exerting depends directly on the number of its molecules present in the mixture E all of the above The next three questions relate to a mixture of noble gases consisting of 0150 mole of He 0450 mole of Ne and 0300 mole of Ar 346 The mole fraction of Ar in this mixture is A 0300 B 0333 C 0667 D 0500 347 The partial pressure of the Ne in the mixture is 275 Torr The total pressure of the mixture is A 550 Torr B 275 Torr C 611 Torr D 900 Torr 348 The partial pressure of the He is A 183 Torr B 275 Torr C 917 Torr D 157 Torr 349 The 02g generated by the decomposition of KClO3 was collected by the displacement of water at 31 C vapor pressure of H20 320 mmHg The wet gas had a volume of 758 mL The barometric pressure during the collection process was 683mmHg What pressure did the 02g exert A 715 mmHg B 683 mmHg C 651 mmHg D 667 mmHg 350 How many grams of 02g were generated in the process described in the previous question A 260 X 10393 B 833 X 10392 C 255 X 10392 D 677 X 10393 KINETIC MOLECULAR THEORY OF GASES 351 The kinetic molecular theory of gases was developed to eXplain the behavior of A real gases B noble gases C ideal gases D inert gases 352 Which of the following statements is not a postulate of the kinetic molecular theory of gases A The volume of the molecules making up the gas is negligible compared to the distances between the molecules B The gaseous molecules move constantly and randomly in straight lines throughout the volume of the container C The attractive forces between molecules are essentially negligible D The average kinetic energy of the molecules is directly proportional to the pressure they eXert 353 The gaseous state is the simplest state of matter to study because the identity of the gas is irrelevant under ordinary conditions This irrelevance is based upon A the fact that the gaseous molecules are electrically neutral B the fact that molecular volume is immaterial under ordinary conditions C the fact that the gaseous molecules neither attract nor repel one another under ordinary conditions D A B and C E B and C COMPARISON OF GASES LIQUIDS AND SOLIDS 354 The least compressible state of matter is the state A liquid B solid C gaseous D irrepressible 355 This substance is a uid of relatively high density It conforms to the shape but not the volume of its container It is a A gas B solid C liquid D plasma 356 Unlike gases liquids and solids vary widely in their properties under ordinary conditions because A they differ widely in the size of the particles making up the substance B they differ widely in the nature of attractive forces between particles C they differ widely in the strength of the attractive forces between particles D all of the above PHASE TRANSITIONS 357 Each of the following equations describes a phase transition accompanied by the term used to specify the transition In the list one mismatch is included Select the mismatch A solid gt gas sublimation B liquid gt solid fusion C liquid gt gas vaporization D gas gt liquid condensation 358 Consider the change liquid gt solid In this change A thermal energy is released as heat to the surroundings B the temperature of the system slowly drops C an endothermic process occurs D all of the above 359 During a phase transition the system is in a state of dynamic equilibrium Such an equilibrium is characterized by A change occurring in both the forward and reverse direction B a very slow change in the temperature of the system C change occurring in opposite directions at the same rate D the temperature of the system remaining constant E A and B F C and D 360 Above the liquid phase in a sealed container eXists a gaseous phase exerting a constant pressure This pressure is termed Athe ambient pressure B the endoatmospheric pressure C the equilibrium vapor pressure D the amphoteric pressure 361 The vapor pressure of a liquid or of a solid can be changed by changing A the external pressure ie the atmospheric pressure B the surface area of the liquid C the temperature of the liquid D the humidity ie the moisture content of the atmosphere 362 For the process H20s H H20l AH 601kJ This equation tells us that A the process is endothermic B to melt one mole of ice 601 H must be provided C the process is an equilibrium process D all of the above 363 Using the data supplied in the previous question calculate the change in enthalpy When 500 g of H20l freezes A 601 H B 601 H C 167 kJ D 167 kJ 364 A sample of liquid water in the amount of 1000 g absorbs 226 kJ in boiling Calculate the molar heat of vaporization of water A 2260 Jmol B 407 kJmol C 4070 Jmol D 226 kJmol PHASE DIAGRAMS 365 A phase diagram for a given substance shows graphically A the physical state of the substance at a given temperature pressure combination B those temperaturepressure combinations Which specify the phase equilibria of the substance C the temperature above Which only the gaseous state eXists D all of the above 366 At one specific temperature and pressure combination the gas liquid and solid states of a given substance are in equilibrium This TP combination is A the critical point B the equilibrium point C the triple point D the coeXistence point 367 In a phase diagram a line segment separates the liquid from the solid state A point along this line designates a pressure of 6 atm and a temperature of 560C These data tell us that A the substance is a pure solid at this T and P B the substance is a pure liquid at this T and P C at 6 atm the substance melts at 560C D at 6 atm the substance freezes at 560C E C and D 368 The triple point of water is 001 C and 458 Torr This information tells us that at a pressure less than 458 Torr A ice cannot eXist B steam cannot eXist C liquid water cannot eXist PROPERTIES OF THE LIQUID STATE 369 A liquid s resistance to ow is termed its A surface tension B viscosity C cohesion D capillarity 370 The viscosity of a liquid is and its vapor pressure is by an increase in the temperature A increased increased B decreased decreased C increased decreased D decreased increased 371 Although a needle can be made to oat upon water the addition of soap causes the needle to sink This effect occurs because A the soap lowers the viscosity of the water B the soap lowers the vapor pressure of the water C the soap lowers the surface tension of the water D the soap lowers the meniscus of the water INTERMOLECULAR FORCES 372 Intermolecular forces are electrical in nature are weaker than chemical bonds vary in strength depending upon the distance between molecules vary depending upon the nature and identity of the molecules UOUIJgt E account for the formation of the liquid and solid states F all of the above 373 The intermolecular attractive forces in Substance I are stronger than those in Substance II Therefore A I has a lower vapor pressure than does II B I has a lower heat of vaporization than does II C I has a lower melting point than does II D I has a lower boiling point than does II E all of the above 374 Identify the intermolecular force from its description acts on all molecules depends upon the occurrence of an instantaneous snapshot dipole which induces dipoles in surrounding molecules dipoledip ole interactions covalent bonding hydrogen bonding London dispersion forces DOW 375 Only molecules containing a N O or F atom eXperience A dipoledipole interactions B covalent bonding C hydrogen bonding D Londondispersion forces 376 This type of intermolecular attraction has been described as an extreme form of dipoledipole interaction A covalent bonding B hydrogen bonding C London forces D ionic bonds 377 Which of the following species eXperiences only London forces A HCl B H20 C NH3 D CH3CH3 378 Which of the following is subject to dipoledipole interactions A H2 B He C C02 D H28 379 Consider an ammonia molecule It eXperiences A dipoledipole interactions B London forces C hydrogen bonding D all of the above 380 Which of the following experiences dipoledipole interactions HINT review VSEPR A CH4 B SiF4 C TeCl4 D XeF4 381 In general the strongest type of intermolecular force is A dipoledipole interactions B covalent bonding C hydrogen bonding D London or dispersion forces 382 Consider the two molecules CH3OCH3 an ether and the alcohol CH3CHZOH The alcohol has a higher vapor pressure than does the ether B The alcohol has a lower freezing point than does the ether C The alcohol has a higher boiling point than does the ether D All of the above gt 383 Following the usual trend the boiling points of the hydrogen halides should increase systematically from the lowest for HF to the highest for HI Instead HF has the highest boiling point Which of the these explanations for HF s anomalous behavior is the accepted explanation A The HF molecule is so light in mass it possesses exceptionally high kinetic energy B The lone pairs on the F atom are drawn so close to the nucleus that the molecule experiences very weak attractive forces C The presence of the fluorine atom which is very highly polarizable causes the molecule to experience very strong London forces D The hydrogen atom of one HF molecule is strongly attracted by a lone pair of electrons on the fluorine atom of an adjacent HF molecule TYPES OF SOLIDS 384 Amorphous solids differ from crystalline solids in that A crystals have a welldefined orderly structure amorphous solids do not B crystalline solids have sharp melting points amorphous solids do not but soften over a temperature range C the particles making up a crystalline solid are restricted to specific sites in the solid the particles making up an amorphous solid are not so restricted D all of the above 385 A solid in which cations surrounded by freely moving valence electrons form the crystal lattice is a solid A ionic B network covalent C molecular D metallic 386 Diamond consists of an orderly threedimensional array of carbon atoms forming an extremely hard solid It is an example of a solid A ionic B network covalent C atomic D molecular E metallic 387 Which type of crystalline solid is 802 most likely to form A ionic B network covalent C atomic D molecular E metallic 388 Which of the following solids should have the highest melting point A argon B sulfur dioxide C methane D sodium nitrate E water 389 This solid is not a conductor of electricity but its aqueous solution is This solid is A P4 B SiO2 C NaSCN D C60 390 The crystalline solid can be constructed by stacking together in three dimensions A crystal lattices B unit cells C repetitive cells D crystal boxes 39lIn most the crystal lattices have cubic or hexagonal structure A ionic compounds B molecular species C metals D network covalent species 392 A network covalent substance having a layered structure is A graphite B diamond C silicon D germanium SOLUTIONSGENERAL 393 Which of the following general statements about solutions is correct A When a gas dissolves in a liquid the liquid is always the solvent B When a solid dissolves in a liquid the liquid is always the solvent C When a liquid dissolves in another liquid the liquid present in the greater amount is the solvent D All of the above 394 At 20 degrees Celsius the solubility of NaCl is 360 g per 100 g of water To 100 g of water at this temperature 300 g of NaCl is added This solution is best described as A supersaturated B saturated C unsaturated D dilute 395 To produce NaClaq at 20 degrees Celsius 400 g of NaCl is mixed with 100 g of water Which of the following statements about this mixture is correct A A saturated solution has formed B At the bottom of the solution sits 40 g of solid NaCl C the solution and the solid constitute a system in a state of dynamic equilibrium D All of the above 396 Often as a solubility rule the phrase like dissolves like is used This eXpression is valid because A substances having about the same molecular mass tend to be mutually soluble B substances eXperiencing the same type of attractive forces tend to be mutually soluble C substances similar in composition tend to be mutually soluble D substances having similar equilibrium vapor pressures tend to be mutually soluble 397 Which of the following is considered to be insoluble in water A NH3g B C2H50Hl C CH4g D CaC12s 398 Benzene is a liquid hydrocarbon Predict which of the following is most likely to be soluble in benzene A HZO1 B C6H14l C CH3COOH1 D CH3OH1 399 When an ionic compound dissolves in water the is released Alattice energy B energy of hydration C vaporization energy D bond energy 400 The two energy changes that in uence the formation of aqueous solutions of ionic compounds are A ionization energy and electron affinity ionization energy and hydration energy electron affinity and hydration energy electron affinity and lattice energy hydration energy and lattice energy mUOU 401 Which of the following cations eXperiences the greatest energy of hydration A Li B Na C K D Rbt 402 Which of the following ions eXperiences the greatest energy of hydration A Na B Mg2 C Al3 D N339 403 Which of the following compounds possesses the greatest lattice energy A MgOH2 B CaOH2 C SrOH2 D BaOH2 EFFECT OF T AND P ON SOLUTIONS 404 A gas is most soluble in a liquid at low temperature and low pressure high temperature and high pressure low temperature and high pressure high temperature and low pressure 405 High temperatures increase the solubility in UOUIJgt water of most A gases B ionic compounds C hydrocarbons 406 When ammonium nitrate dissolves in water the solution cools because the solution process is A endoentropic B exoentropic C endothermic D exothermic 407 Acetylene gas at room temperature dissolves to the extent of 320 g per liter of liquid acetone at 12 atm pressure Determine the Henry s law constant for acetylene in acetone at room temperature A00375 L atmg B 267 gL atm C 3840 g atmL D 0260 Lg atm 408 Calculate the solubility of acetylene in acetone at room temperature and a pressure of 5 atm A 187 gL B 195 gL C 134 gL D 173 gL SOLUTIONS CONCENTRATION UNITS 409 Which of the following concentration units changes With changes in temperature A mass percent B mole fraction C molarity D molality E ppm 410 A solution is prepared by dissolving 0100 mole of HCl in 750 g of water Calculate the mass percent HCl in this solution A 0133 B 464 C 487 D 401 411 Any mixture of gases is a solution Such a solution is prepared by mixing 100 g of He 100 g of Ne and 100 g of Ar The mole fraction of Ar in this mixture is A 00769 B 0333 C 0156 D 000321 412 A solution is prepared by dissolving 100 g of HCl in sufficient water to produce 150 mL of solution Calculate the molarity of this solution A 0194M B 183M C 667M D 322M 413 A solution is prepared by dissolving 200 g of NaOH in 750 g of water The molality of this solution is A 267m B 00267m C 0667m D 0000667m 414 A 500 by mass solution of HNO3aq has a density of 131gmL Calculate the molarity of this solution A 104M B 147M C 115M D 977M 415 Calculate the molality of the 500 nitric acid solution A 191m B 167m C 159m D 104m 416 Calculate the mole fraction of nitric acid in 500 nitric acid solution A 0794 B 0195 C 0500 D 0222 417 The antiseptic H202aq is 0655 molal in the hydrogen peroxide Calculate the mole fraction of peroxide present A 00118 B 00116 C 0119 D 0211 COLLIGATIVE PROPERTIES 418 Colligative properties are the properties of a solution that depend upon A the identity of the solute particles present in the solution the size of the solute particles the identity of the solvent of the solution the size of the solvent particles the number of solute particles present the number of solvent particles present TUFUUOW 419 Colligative properties include vapor pressure lowering boiling point elevation freezing point depression osmotic pressure all of the above wccwgt 420 A nonvolatile nonelectrolyte in the amount of 00900 mole is dissolved in 1000 g of water Given that to 25 C the vapor pressure of pure water is 238 Torr calculate the vapor pressure of the solution A 238 Torr B 0379 Torr C 234 Torr D 0369 Torr 421 Calculate the freezing point in 0C of a solution containing 00100 mole of a nonelectrolyte in 1000 g of water A 0186 B 0186 C 0010 D 0010 422 Calculate the boiling point of the solution of Question 421 A 100050C B 100200C C 99950C D 99800C 423 The freezing point of a solution of a nonelectrolyte in benzenemp54550C freezing point depression constant 50650C is 42000C Calculate the molality of this solution A 0159m B 0591m C 0248m D 0721m 424 Given that benzene has a normal boiling point of 802 C and a boiling point elevation constant of 2610Cm the solution of Question 423 Will boil at A 808 C B 7960C C 8060C D 7980C 425 Calculate the osmotic pressure of a 00010 M solution of a nonelectrolyte at 25 C A 16 mmHg B 73 mmHg C 14 mmHg D 19 mmHg 426 Calculate the molarity of a solution having an osmotic pressure of 360 Torr at 25 C A 144 M B 194 X 10392 M C 304 X 10394 M D 0721 M COLLOIDS 427 The scattering of light be colloidalsize particles is termed A Brownian motion B the Tyndall effect C coagulation D homogenation 428 A micelle is an example of A a hydrophobic colloid an association colloid a hydrophilic colloid a hemophilic colloid U003 429 In general colloidal particles remain dispersed because of A their size B their mass C their rapid motion D their electric charge 430 An emulsion is a colloid in Which A a gas is dispersed in a liquid B a liquid is dispersed in a gas C a liquid is dispersed in a liquid D a solid is dispersed in a liquid 431 Smoke is an example of a colloid termed A a foam B an aerosol C a gel D sol 62 Chapter 6 Lecture 2 Last time I ended with a discussion of thermochemical equations77 that allow us to relate heats enthalpies of reactions to the balanced chemical equation Today we ll start with a worksheet on that topic Key points to remember See overhead 1 The enthalpy of reaction is the heat absorbed by the system for one mole of the reaction as written 2 Doubling the quantities in a reaction requires doubling of the enthalpy 3 Reversing a reaction leads to a change in sign for the enthalpy 4 ln stoichiometry calculations related to heat the balanced thermochem ical equation gives conversion factors for heat and moles For example for the propane example on the handout 5 mol 02g 2220 kJ Give students 10 minutes to work on the handout plus a few minutes more at the end if needed The concepts on the handout are related to Hess s law Before we discuss this further however I d like to give a brief description of how we can measure the heats associated with a chemical reaction How do we know these numbers Calorimetry is the measurement of heat changes Key principle We usually measure the ow of heat by measuring changes in temperature Adding heat to a system increases its temperature taking heat away decreases its temperature The temperature change for a given ow of heat depends on the amount of the substance present and on the heat capacity of that substance Heat Capacity C The amount of heat required to raise the temperature of a given quantity of the substance by one degree Celsius The speci c heat s of a substance is the amount of heat required to raise the temperature of 1 gram of that substance by 1 degree Celsius So speci c heat and heat capacity are related by the mass 0 2 ms The speci c heat of water is 4184 JgOC or 1 calgOC How much heat is required to raise the temperature of 500g of water from room temperature 25 C to its boiling temperature 100 C Let q 2 heat q msAt em 500 g418475 C 157 x 105 J 157 kJ What is the heat capacity of 500 g of water 500 X 4184 2092 kJOC Multiply this by 75 and you get the same answer as above of course One day we were haVing a dinner at our house for about 1215 people I borrowed a big pot from some friends so I could make enough spaghetti for all But I didn t gure on how long it would take to boil that water I m used to about a 6quart pan and this one held like 30 quarts Add heat at a constant rate to 6quart and 30quart pans and the 6quart pan will reach boiling temperature roughly 5 times faster This is because the heat capacity of 30 quarts of water is 5 times larger than the heat capacity of 6 quarts of water Example problems heat capacity and speci c heat The speci c heat of ethanol CQH50H is 246 JgOC A sample of 25 kg ethanol is heated from 75 C C to 550 0C The amount of heat absorbed by the ethanol is equal to Give the students a couple of minutes to solve Solution q msAT 25 x 103 g246Jg C550 C 7500 292 x 105 J Another example The speci c heat of water is 4184 JgOC If 20 x 107 J of heat is added to a bathtub containing 200 L of water initially at a temperature of 20 C what is the nal temperature of the water Assume water has a density of 10 gmL Give a few minutes for a student solution 10 200 x 103mL gtlt 2032100 9 1 mL q 20 x 107 J 0 T 20 C7 239C ms 209310a g4184Jg 390 C T 439 C around 111 F In calorimetry experiments we measure the heat given off in a reaction by measuring the temperature change in its surroundings Let s briefly discuss calorimetry experiments now On the overhead is a diagram of a bomb calorimeter Overhead Describe its components sample vessel ignition wire Bomb oxygen inlet water thermometer stirrer insulated jacket Question So is the overall system open closed or isolated Isolated Initiate the reaction and heat ows from the sample to the bomb and the surrounding water I m assuming an exothermic reaction here The overall heat ow into the system is zero since it is isolated gsystem Qwater qbomb grwn OI grwn qwater qbomb The sign difference simply means heat ows from the sample to the water and bomb We measure the temperature change We want to determine qmn How do we do this By using the relationship q msAt CA2 For the water we know its speci c heat So all we have to measure is the mass or volume of water Qwater mwater For the calorimeter we need to know its heat capacity This is usually de termined from experiment with electrical heating 100mb CbambAt These equations should look familiar from the review questions at the begin ning Example 1435 g of naphthalene was burned in a constant volume calorime ter The temperature of the water 2000 g rose from 2017 to 2584 C the heat capacity of the calorimeter was found to be 180 kJ C Calculate the molar heat of combustion of naphthalene These equations are review from above qwate msAt 2000 x 4184 x 2584 2017 474 x 10 1 J 474 M qub Cbmbm 18 x 2584 2017 102 14 So grwn qwater qbomb 576 kt Finally the molar mass of naphthalene is 1282 gmol 576 kJ 1282 g k 1435 g X 1 mol 515 Mm This is approximately equal to the enthalpy of reaction but not exactly A small correction term can be applied to determine AH exactly There are also constant pressure calorimeters such as the styrofoam calorime ter shown in Fig 66 These are commonly used in undergraduate chemistry laboratories In this case q does equal AH See Example 63 for a sample calculation Time for worksheet