Fundamentals of Chemistry
Fundamentals of Chemistry CHEM 1331
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CHEM 1331 REVIEW CHAPTER 8 n describes shell n and K describe subshell Use shell and subshell to set up ENERGY LEVEL DIAGRAM 4p 3d 4s 3p 3s 2p 2s ls Assign FOURTH QUANTUM NUMBER s or m5 7 spin 12 or 712 USE THREE RULES TO PUT ELECTRONS IN AUFBAU electrons want lowest possible orbitals PAULI no more than 2 electrons in each orbital no two electrons in a given atom can have same set of 4 quantum numbers HUND if there s a choice electrons go in empty orbital before in one with one electron CANNOT VIOLATE PAULI or HUND IF VIOLATE AUFBAU EXCITED STATE ELECTRON CONFIGURATION b f 1 ct Use rules to put 1n electrons 7 write as subshellquotum em 6 6 ms USE PERIODIC TABLE TO REMEMBER ORDER OF ENERGY LEVELS First s is ls 2 electrons MAX in each s subshell First p is 2p 2 electrons MAX in each p subshell 2 electrons MAX in each p orbital First d is 3d 10 electrons MAX in each d subshell 2 electrons MAX in each d orbital First f is 4f 14 electrons MAX in each f subshell 2 electrons MAX in each f orbital SHORTHAND start from previous noble gas EXCEPTIONS d and f subshells prefer to be half or all lled Cr Ar4s13d5 NOT Ar4s23d4 Mo similar Cu Ar4s13d10 NOT Ar4s23d9 Au Ag similar MAKING IONS Remove or add electrons to improve stability of electron con guration ADD ELECTRONS IN SAME ORDER AS ABOVE REMOVE ELECTRONS FROM HIGHEST SHELL FIRST Fe is Ar4s23d6 Fe is Ar3d6 GROUPS IN PERIODIC TABLE Atoms in same group have same VALENCE electron con guration pattern 7 similar properties except for metalnonmetal split Group 1 Alkali metals noble gasns1 Group 2 Alkaline earth metals noble gasns2 Group 7 Halogens noble gasns2np5 Group 8 Noble gases noble gasns2np6 ALSO KNOW dblock transition metals f block inner transition metals PERIODIC PROPERTIES FIRST IONIZATION ENERGY atom gt atom electron SECOND IONIZATION ENERGY atom gt atomzl electron Generally increase UP AND TO RIGHT BUT Very high if breaking lled p Higher than expected if breaking lled s or half lled p Lower than expected if making lled s or p or half lled p So for rst period rst IE Li ltBlt Be ltC ltOltN ltF ltNe secondIE BeltCltBltNltFltOltNeltLi ELECTRON AFFINITY atom electron gt atom39 inc exothermic UP AND TO RIGHT usually written as positive METALLICITY Increases to LEFT AND DOWN This includes conductiVity and basicity of oxides NON METAL Increases to RIGHT AND UP Acidity of oxides REACTIVITY For metals INCREASES TO LEFT AND DOWN For nonmetals INCREASE TO RIGHT AND UP ATOMIC SIZE Increases to LEFT AND DOWN IONIC SIZE Cations SMALLER than atom 7 bigger charge smaller they get Anions LARGER than atoms 7 bigger charge bigger they get ISOELECTRONIC same number of electrons 7 size decreases as charge gets more positive PARAMAGNETIC unpaired electrons DIAMAGNETIC no unpaired electrons CHEM 1331 CHAPTER 6 PROBLEMS You might nd the following AH values useful at some stage in this 39 AH ldmol 39 AH ldmol 39 AH CaCO3s 71210 CaOs 7636 COzg 7393 C2H2g 227 C2H4g 525 C2H6g 7847 HZOl 7286 H20g 7242 HzSO4l 814 SOzg 297 SOgg 396 SOzClzg 364 1 A system that does no work but which receives heat from the surroundings has A qlt0AEgt0 B qAE C qAE D qgt0AElt0 2 A system receives 205 J of heat and 225 J of work Calculate the change in the internal energy AE of the system A 430 J B 430 J C 20 J D 20 J 3 Which of the following statements is NOT true A if work is done on a system w gt 0 B in endothermic changes heat flows from the surroundings to the system C when heat is lost by a system such as a cup of tea q lt 0 D the internal energy of a system changes ONLY when heat is gained or lost by the system E internal energy is a state function but q is not 4 A system receives 575 J of heat and delivers 425 J of work Calculate the change in internal energy AE of the system A 150 J B 1000 J C 1000 J D 575 J E 150 J 5 If 50 1d of energy is added to a 155 g sample ofwater at 100 C the water is A still a liquid B boiling C completely vaporized D frozen solid E decomposed 6 The heat capacity ofbenzene C5H5 is 817 JmolrloCrl How much heat injoules is required to raise the temperature of 390 g of benzene by 100 0C A 419 J B 409 J C 816 J D 1630 J 7 The heat required to increase the temperature of 500 g HZOl from 250 0C to 450 0C is A 116 J B 209 J C 4180 J D 4180 kJ A A A A D A B C E When 450 g ofan alloy at 1000 0C is dropped into 1000 g ofwater at 250 0C the nal temperature is 370 0C What is the speci c heat of the alloy in J g loCrl 0423 B 988 C 177 D 488 150 g of lead metal at 100 C is dropped into 500 g H20 at 220 C When thermal equilibrium is reached T 288 C What is the speci c heat capacity oflead in Jg K 140 X 103 B 013 C 013 D 77 E 054 307 g of an unknown mineral is heated to 987 C and placed into a calorimeter that contains 724 g of water at 236 C The heat capacity ofthe empty calorimeter was 157 JK The nal temperature of the calorimeter was 324 C What is the speci c heat capacity of the mineral in JgK 0138 B 0124 C 0131 D 0150 E 0145 A 100 g sample ofNH4NO3 is decomposed in a bomb calorimeter which has a heat capacity including the water of 123 k K l The temperature increases by 612 K What is the molar heat of decomposition for ammonium nitrate 7602 kJmol1 B 753 ldmolr1 C 7398 kJmol1 D 164 kJmol1 10 g of methane CH4 is combusted in a calorimeter that has an empty heat capacity of 18 J C The calorimeter contained 150 g of water If the temperature changed from 252 C to 303 C calculate the molar heat of combustion of methane in Jmol 3293 B 3293 C 5270 D 8568 E 1370 The heat capacity ofa calorimeter is 490 ld C When 1010 g of sugar C12H22011 is burned in the calorimeter the temperature increases from 2492 C to 2833 C How much heat is released by combustion of one teaspoon of sugar assume 480 g of sugar in a teaspoon 794 1d B 488 J C 119 1d D 167 k E 348 k The standard enthalpy of formation of COzg is equal to which of the following AHfCOg AHfOzg AH of combustion of COg C 0 kJmol 13 AH of combustion of graphite Cs E none of these Which of these statements is FALSE Aern can be calculated from ZmAHfreactants ZnAHfproducts where m and n are coefficients of reactants and products in the balanced equation For elements and compounds the standard state is the physical state of the substance at 1 atm and usually at 25 C For a substance in aqueous solution the standard state is 1 molar concentration Any substance in its natural state is assigned a AHf of 0 kJmol For a gas the standard state is at a pressure of 1 atm 2 16 Cold packs in which temperatures are lowered when ammonium nitrate dissolves in water are used extensively in athletics etc Which of the following is true about the dissolution process A AH lt 0 process is exothermic B AH lt 0 process is endothermic C AH gt 0 process is exothermic D AH gt 0 process is endothermic 17 Which of the following processes is endothermic A 2H2g 02 gt 2 H20g B H20g gt H200 C CH4g t 2 02 gt C02g t H20g D H20S gt H200 18 For which of these reactions or changes is AH lt 0 1 02 gt 2 Og 2 H20g gt H20l 3 H20 at 25 C gt H20 at 75 C A 1 and 2 B 1 and 3 C 1 only D 2 and 3 E 2 only 19 The heat of combustion for one mole of carbon is 410 kJ Cs 02g gt COzg How many k of heat would be liberated on the complete combustion of 60 g of carbon A 2050 k B 18040 1d C 4920 k D 24600 1d 20 Calcium hydroxide which reacts with carbon dioxide to form calcium carbonate was used by Romans as mortar in stone structures 7 CaOHzs COzg gt CaCO3s HzOg AH 691 k What is the enthalpy change if 380 mol of calcium carbonate is produced A 263 1d B 055 k C 69 k D 263 k E 18kJ 21 Calculate the standard enthalpy of combustion of C2H5 in kJmol 1 using the equations Hzg 1202g gt H200 AHO 7286 kJ CzH4g Hzg gt Cszg AHO 7137 kJ C2H4g 302g gt 2C02g 2H20l AHO 71412 k A 7127510 B 4561M C 4548M D 1834kJ 22 Given these equations calculate the heat of formation of XO3g Assume X is a metal X02g gt 02g Xs AH 300 k 2 X02 t 02 gt 2X03g AH 7200 M A 7500 ker1 B 100kJmol1 C 7400 ker1 D 200kJmol1 23 From the equations below how much energy is produced in the combustion of 28 g of CO 2Cs 02g gt 2C0g AH 218 kJ Cs 02g gt COzg AH 393 k A 88 1d B 109 k C 175 k D 284 k 3 24 Calculate the standard enthalpy of formation of NOg in kJmol using the enthalpies given 2 NOg 02g gt 2 NOzg AH 114 k 4 Noxg 02g a 2 NzOsg AH 110 Id 2 Nzg 5 02g gt 2 N205g AH 226 k A 902 B 617 C 141 D 790 E 352 25 Calculate the Aern for 2 NOg 3 2 02g gt N205g using the enthalpies given NOg 12 02g gt NOzg AH 571 1d 2 NOzg 12 02g gt N205g AH 1095 k Nzg 02g gt 2 NOg AH 1806 k A 7111d B 531kJ C 2237 1d D 1666 1d E 140 1d 26 Calculate the value of AH for this reaction C2H4g Hzg gt C2H5g A 71372 k B 322 1d C 7322 k D 1372 k 27 What is AH in k for the reaction 2C2Hz 502g gt 4COzg 2HzOg A 1829 B 2283 C 2510 D 1602 28 At 298 K the reaction represented by CaCO3s gt CaOs COzg is A exothermic with AH 181 k B endothermic with AH 181 1d C endothermic with AH 134 1d D endothermic with AH 181 1d 29 AH for the reaction below is 62 1d Calculate the value of AHfquot in kJmol for HClg SOzClzg H20l gt HzSO4l HClg A 184 B 60 C 92 D 30 E 102 30 The standard enthalpy change for the combustion of methanol CH30H is 6385 kJmol Given the values below what is the standard enthalpy of formation of methanol in kJmol AHf of H20 2418 ldmol and ofCOz 3935 ldmol A 32 B 5484 C 2386 D 5484 E 1274 31 Given that the AHf for CuzOs is 169 kJmol and that for CuOs is 157 ldmol calculate the Aern for CuzOs 12 02g gt 2 CuOs A 12 k B 181 k C 12 1d D 145 k E 145 1d ANSWERS CADAAlBCCBAlACADDlDDEAAlBCDAClACDCClE 1331 REVIEW CHAPTER 6 FIRST LAW OF THERMODYNAMICS Energy cannot be created or destroyed Focus on reactions as system CALORIMETRY AEsystem AEsurroundings AE q w q is heat given to reaction w work done on system ApV or AnRT 7 only important for gases heat change speci c heat X mass X AT heat change heat capacity X AT heat change of system heat change of water heat change of cal READ QUESTIONS TO SEE HOW TO CALCULATE q De ne system and surroundings Reaction serves as system STATE FUNCTION Function whose change is independent of path AE is q and w not ENTHALPY TYPES OF AH STANDARD STATE HESS LAW heat of reaction at constant pressure 7 change is AH state function Of reaction refers to reaction as written in moles 7 use Stoichiometry AHcombustion 7 heat when 1 mole reacted with 0Xygen AHformation 7 heat change when 1 mole made from elements IN THEIR NATURAL STATE AHf Pure solids or liquids 1 atm pressure 1 M concentration 25 C usually 1 combine reactions to get overall reaction do same for AH s Remember if you switch reaction around change sign of AH 2 AH EAHfproducts EAHfreactants CHEM 1331 REVIEW QUESTIONS CHAPTERS 9 AND 10 Lewis Dot Structures and Peripherals 1 An acceptable Lewis dot structure for N20 is O O 0 O Ao N o B20 C of N N o o o O O o o O O D O N N E O N N O O O O 2 Which molecule contains one unshared pair of valence electrons A H20 B NH3 C CH4 D NaCl 3 The most reasonable Lewis structure for NOCl is 00 o 00 00 o 0 06 Colo A 0 N Cl B 0 01 C o H o o o o o O 0 o o o o o o o o o o D 20 N CI E 2 N 0 Cl 0 o o o 0 0 0 o 4 How many electrons should be shown in the Lewis dot structure for carbon monoxide A 8 B 14 C 10 D 28 5 The Lewis structure of NOf is best drawn as 00 oo 00 00 oo 00 0 o A 0 N 0 B0 N C 0 N 0 O O O O O O O O O O O o o o o D 0 N O gt E oN O O gt o o o o o o 6 Which has a Lewis dot structure with the greatest number of unshared pairs on the central atom A NH3 B IF3 C SeClz D IClz39 7 Which molecule contains only two unshared pairs of electrons A H20 B NH3 C BeClz D MgO 8 A D A 13 Which has an incorrect arrangement of electrons 2 2 szzN B Mg 0 O O O O E C a E c C O B Br E In the Lewis structure of SF there are single bonds and total lone pairs 28 B 38 C 22 D 26 E 36 Which of the following species is INCORRECTLY matched with the number of lone pairs found on the central atom SO4239 0 B N0339 1 C Xer 3 D S02 1 E IF439 2 Which of the following molecules Violates the octet rule CBr4 B NF3 C OFz D PC13 E AsF5 Which of these contains at least one multiple bond N0339 B PH3 C N2H4 D SiCl4 E BH439 Sulfur dioxide can be described by the structures below This implies that O O O O O O 0 s 0 4 0 s 0 O O O O the two bonds in S0 are of equal length and the electronic distribution in the two SO bonds is identical the single bond is longer than the double bond and the electronic distribution in the two SO bonds is different an electron pair in the SO molecule alternates back and forth between the two sulfurioxygen electron pairs so that the two different bonds seem to exchange positions the SO molecule revolves so that the two different bonds seem to exchange positions How many different resonance forms are possible for the oxalate anion CzO4z39 3 B 7 C 6 D l E 4 Which molecule exhibits resonance 03 B BeClz C CO D HzSe E NF3 What are the formal charges on the boron and nitrogen in the compound BF3NH3 2 and 2 B 2 and 72 C 0 and 0 D 1 and 71 E l and 1 17 A B C D 18 A C 19 20 The structure of the CO32 ion can be described by these Lewis structures which means that 0 0 C O 0C o C o o 0 0 9 two CO bonds are single bonds the third CO bond is a double bond three independent forms of the CO32 ion coeXist in equilibrium the electrons must be rapidly exchanging among the three forms the C032 ion eXists in only one form which is a composite or average of the three principal structures shown Which is the least signi cant contributing structure to the resonance hybrid of the nitrate ion 3 B 0 N N 2NIlti ziciN2 What are the formal charges on each of the atoms in the PH4 ion A P0H B P0H0 C P4H l D P1H0 EP0H1 What is the formal charge on the sulfur atom in the sulfate anion 2 B 0 C 2 D 4 E 6 A 21 What is the formal charge on the nitrogen atom in the nitrate anion A 2 B 1 C 0 D 1 E 2 22 Given the bond energies in kJmol below calculate the heat of reaction in kJ for Cg 2Hg 2Fg gt CH2F2g CiH 414 CiF 486 HiH 435 FiF 159 HiF 569 A AH 900 C AH 900 B AH 4165 D AH 1800 23 Calculate AH for the NH3g Clzg gt NH2C1g HClg using the bond energies NiH 389 CliCl 243 HiCl 431 NiCl 201 A 337 k B 337 k C 84 k D 0 k 24 Calculate AH for the reaction C2H4 H20 gt C2H50H using the following bond energies in kJmol CH 413 C0 358 CC 347 OH 467 HH 432 CC 614 CO 799 A 37 B 179 C 441 D 304 E 2098 25 Using the bond energies given estimate the AH for making carbonic acid H2C03 from C02 and H20 CH 413 C0 358 CC 347 OH 467 CO 799 CEO 1070 A 493 kJmol B 493 ldmol C 83 ldmol D 799 ldmol E 467 kJmol ELECTRONEGATIVITY AND BOND POLARITY 26 Which would be expected to be the most electronegative A P B As C Si D Al 27 The element with the greatest tendency to gain electrons is A F B At C O D N E Bi 28 Which atom has the highest electronegativity A Br B Mg C C D O 29 Which of these elements should be the most active as a nonmetal given that their electronegativity values are Q 09 R 10 T 28 X 30 Z 40 A Q B R C T D X E Z 30 Which of the following statements about electronegativity EN is FALSE A Nonmetals usually have higher EN than metals B Electronegativities can be directly measured experimentally C HCl has a higher partial ionic character than HI because the EN of C1 gt EN of I D In general an atom s EN is inversely related to its radius 31 In which bond are the partial charges on the atoms correct A 5Si 0 539 B BIClBrs39 C BtN BB39 D 5C1 C1539 32 Which of the following compounds contains the LEAST polar bonds Atoms H S P As Cl Si Sb Electronegativity 21 25 21 21 30 18 19 A PH3 B AsC13 C SiH4 D SbC13 E HzS 33 Which set of bonds is arranged in order of increasing polarity A SiS lt SiO lt SiP lt SiF B SiO lt SiF lt SiS lt SiP C SiF lt SiS lt SiO lt SiP D SiP lt SiS lt SiO lt SiF 34 The BrCl molecule may be represented by the formula BrCl The polarity is best represented as A 13r5tC16 B 13r51C16 C Br51C1E D BraC15 IONIC BONDING 35 The lattice energy for ionic crystals increases as the charge on the ions 7 and the size of the ions 7 A increases increases B increases decreases C decreases increases D decreases decreases 36 Select the compound with the highest most negative lattice energy A CaS B MgO C NaI D LiBr 37 Select the compound with the lowest least negative lattice energy A CsBr B NaCl C SrO D CaO 38 Calculate the lattice energy for LiBrs given the following information Lis gt Lig AH 166 kJmol AHf LiBr 351 kJmol Brzl gt 2 Brg AHquot 194 kJmol EA of Brg 325 kJmol IE of Lig 520 ldmol A 906 B 1575 C 1479 D 809 E 351 39 Use a BomHaber cycle based on the formation of MgO to determine AH for the process Og 2e gt Oz39g in kJmol Mgs gt Mgg AH 150 kJmol AHf MgO 602 ldmol Lattice energy of MgOs 3920 ldmol IE1 IE2 Mg 2180 kJmol Bond energy of 00 498 ldmol A 1314 B 740 C 137 D 1786 E 141 40 Calculate the lattice energy of magnesium sul de given that in kJmol Mgs gt Mgg AH 153 IPl Mg IP2 Mg AH 700 1480 AHf MgS AH 343 Sss gt 8Sg AH 4460 EA1 S EA2 S AH 100 203 A 6833 kJmol B 2930 kJmol C 2244 kJmol D 6147 kJmol 41 Calculate the electron affinity of chlorine from the following data in ldmol Rbs gt Rbg AH 858 IP Rb AH 3975 BE C12 AH 226 AH1attRbCl AH 695 AHf RbCl AH 431 A 530 ldmol B 445 ldmol C 417 ldmol D 332 kJmol VSEPR 42 Which pair is geometrically similar A S02 and C02 B CO and OFZ C PH3 and BF3 D S02 and O3 43 The structure for SeF3 is A trigonal pyramidal B square planar C tetrahedral D rectangular planar 44 The molecular structure of BrF5 is A square pyramidal B trigonal pyramidal C trigonal bipyramidal D octahedral 45 Which is planar A NH3 B 8032 C 0032 D H30 46 Which molecule is linear A H20 B NH3 C N02 D C02 E H28 47 A molecule consists of four bonding pairs of electrons and no lone pairs What is its structure A square planar B tetrahedral C linear D square pyramidal 48 A C 49 A C Which statement is true of methane It is a tetrahedral molecule B It contains 80 hydrogen by weight D It contains single and double bonds It does not occur in nature NH3 pyramidal geometry reacts with BF3 planar geometry to form the addition compound H3NBF3 What is the geometry around the nitrogen and boron centers in the addition compound Both centers are tetrahedral B Nitrogenipyramidal and boroniplanar D Nitrogenitetrahedral and boronilinear Nitrogeniplanar and boronipyramidal Which of the following molecules does NOT possess a trigonal pyramidal molecular shape NH3 B C0C12 C H30 D C10339 E PFCI2 Which of these molecules or ions has a square planar structure SiBr4 B NH C C10439 D XeF4 According to VSEPR theory the III bond in 1339 is expected to be 180 B 270 C 90 D 120 E 1095 Predict the real bond angles in BrF3 using the VSEPR theory more than 120 B between 109 and 120 C between 90 and 109 D less than 90 Predict the real bond angles in SeClz using the VSEPR theory more than 120 B between 109 and 120 C between 90 and 109 D 90 Which is the largest bond angle angle 0784 in 8042 B angle FiBeiF in Ber D angle CliCiCl in HCCl3 angle H iH in H20 Which compound would be expected to have the largest dipole moment C02 B BF3 C S02 D CF4 Which molecule is polar BF3 B C02 C CF4 D HZS The bond type and molecular polarity of SiCl4 are Bond Type Polarity 0f Molecule Bond Type Polarity 0f Molecule polar nonpolar B polar polar nonpolar polar D nonpolar nonpolar 7 A 60 A C D 61 A 62 A B 63 A 64 A Which molecule is nonpolar CCl4 B HCl C CF3C1 D CHCl3 E NH3 Experiment shows that the molecule H2Se has a dipole moment Which statement MUST therefore be incorrect The H2Se molecule is linear B The H2Se molecule is electrically neutral There must be a difference in electronegatiVity between hydrogen and selenium The H2Se molecule is covalent Which of the following possesses polar bonds but has a zero net dipole moment BF3 B 02 C CHC13 D PF3 E C12 Of the molecules CO2 NH3 H20 and CH4 which are polar CO2 NH3 and H20 B NH3 H20 and CH4 C CO2 and CH4 CO2 and NH3 E NH3 and H20 Which of the following has a net dipole moment BeCl2 B SF2 C KrF2 D CO2 Which of the following has no net dipole moment CS2 B H2S C CH2Cl2 D PH3 E CH2O GENERAL STUFF 65 A D 66 A D 67 A D Which one of the following properties is least characteristic of substances composed of small covalentlybonded molecules low melting point B poor electrical conductor when solid E low boiling point C weak bonds poor electrical conductor when molten Which of the following properties is least characteristic of metals high melting point B good electrical conductor when solid E high boiling point C brittleness good electrical conductor when molten Which of the following properties is least characteristic of ionic compounds high melting point B poor electrical conductor when solid E high boiling point C brittleness poor electrical conductor when molten ANSWERS DBCCClDADABlEAAEA EDADCTDDDACTAADEBTAADDBl BADBBlDDAAClDBAABlDADCClCDAAAlAEBAClCE CHAPTER 2 QUESTIONS History A The ultimate particles of matter are the atoms of elements which are indiVisible and indestructible B All the atoms of a given element are alike in all respects C The atoms of different elements differ in one or more properties D Compounds are formed by combination of different kinds of atoms 2 When alpha particles were shot at a gold foil target most of the particles were unde ected This indicated to Rutherford that A the gold foil was continuous matter B the mass of the gold atoms was spread out thinly C the atoms of gold were mostly empty space D the alpha particles had great penetrating power E the alpha particles had charges opposite to those on the nuclei 3 The atomic nucleus was discovered experimentally by A William Crookes using a cathode ray tube B Millikan using a cathode ray tube C J J Thomas using a beam of alpha particles D Ernest Rutherford using a beam of alpha particles E Ernest Rutherford using a cathode ray tube Percent by Mass 4 What is the percentage of nitrogen by mass in NH43PO4 A 226 B 124 C 263 D 282 5 The percent by mass of oxygen in CaNO32 is A 228 B 940 C 585 D 470 E 293 6 Calcium carbonate is 40 calcium and 48 oxygen by mass What mass of carbon is contained in 150 lb of calcium carbonate A 12 g B 60 lb C 18 lb D 72 lb E 12 lb 7 Which of the following compounds has the largest percent nitrogen by mass A N2H4 B NH3 C Li3N D NaN3 E LizNH Which assumptions of Dalton s atomic theory had to be reVised or discarded because of the existence of stable isotopes Atomic Structure 8 A atomic mass E 38 electrons 38 protons 52 neutrons 52 electrons 52 protons 38 neutrons The number of neutrons in the nucleus of a specific atom is equal to its B mass number C atomic number D mass number atomic number In all neutral atoms there are equal numbers of protons and neutrons C neutrons and electrons positrons and electrons D electrons and protons Which statement concerning the structure of the atom is correct Protons and neutrons have most of the mass and occupy most of the volume of the atom Electrons have most of the mass and occupy most of the volume of the atom Electrons have most of the mass but occupy very little of the volume of the atom Protons and neutrons have most of the mass but occupy very little of the volume of the atom Which statement is true The nucleus of an atom contains neutrons and electrons The atomic number of an element is the number of protons in one atom The mass number of an atom is the number of protons in the nucleus plus the number of electrons The number of electrons outside the nucleus is the same as the number of neutrons in the nucleus A Cl ion is a chlorine atom that has lost one electron An atom of strontium790 3230 contains B 38 electrons 38 protons 90 neutrons D 52 electrons 38 protons 38 neutrons 127 How many protons are present 1n a I lon 72 B 127 C 54 D 53 E 73 Consider the radioactive isotope bromine80 Select the combination which lists respectively the correct atomic number number of neutrons and mass number for it 45 80 35 B 80 46 35 C 35 45 80 D 35 80 45 E 35 46 81 The species 1H lH and iH represent three allotropes B isomers C homologs D isotopes Elemental tin has several isotopes All of them have the same number of protons B number of neutrons E total number of neutrons and protons total number of neutrons and electrons C mass number 2 A Ions 20 A 21 A B C D E 22 A C 23 A 24 A B 25 A The element X occurs naturally as 200 12X and 800 13X The atomic mass ofX is nearest 122 B 125 C 128 D 130 Rubidium is comprised of two isotopes one of which has a natural abundance of 72 and a mass of 8500 amu Ifthe calculated atomic mass for rubidium is 8556 what is the mass ofthe second isotope 89 amu B 50 amu C 87 amu D 85 amu E 37 amu Lithium has two naturally occurring isotopes 6Li mass 6015121 amu and 7Li mass 7016003 and an overall mass of 69409 amu What is the percent abundance of lithium6 6080 B 8666 C 4616 D 3333 E 7504 Which pair of particles has the same number of electrons Clr Ca2 B Br Se C Ne Ar D Al3t P3 In what respect does an atom of magnesium differ from a magnesium ion Mg The ion has a more stable electronic arrangement than the atom The positive charge on the nucleus of the ion is two units greater than the nuclear charge on the atom The ion has two more protons than the atom The ion will react more readily with free C12 The ion has two more electrons than the atom zoNe 1917 What do these have in common Mg the same number of protons the same number of neutrons B the same number of electrons D the same size Which ion has twentyisiX electrons Crzt B Felt C Nizt D Cult The ions present in solid silver chromate AngrO4 are Ag and CrO42 Ag2 and CrO44 C D Agt Cr and 02 Ag Cr and 02 Which ion is not likely to form from its atoms A1 B sz39 C As339 D Kl E Mg 26 All ofthe following have a 2 charge except A sulfate B dichromate C carbonate D nitrate E sulfite 27 What charge would you expect to find on a selenide ion A 0 B 2 C 1 D 2 E l 28 The ions most commonly formed by calcium aluminum and bromine are A CaA12Br39 B Ca2A1539Br39 C Caz39 A132 Br39 D Caz39A1539Br E Ca2A13Br39 Formulas and Naming 29 NaBrO3 is the correct formula of A sodium bromate C sodium bromite B sodium bromide D sodium hypobromite 30 Which is the correct formulaname combination A AlzSO43 aluminum sulfate B KZPO3 potassium phosphate C C2H3O acetate D PCl3 phosphorus chlorite 3 1 Which name is most consistent with systematic nomenclature for the compound Ni203 A nickel oxide111 B nickel11 oxide C nickel111 oxide D nickel oxide11 32 A compound with the formula CaHz is called A cadmium hydride C calcium hydride B hydrogen carbide D calcium hydrate 33 The correct name of N203 is A nitrogen oxide C nitrogen11 oxide B nitrous oxide D dinitrogen trioxide 34 The formula of calcium nitrite is A C33N2 B CaN02z C CaNO2 D CaN03z 35 The formula of holmium oxide is H0203 Based on this information the formula of the chromate of holmium is expected to be A HoCrO3 B HozCrO32 C HozCrO43 D HozCr207 E HoCrO4 36 If aluminum tungstate is AlzWO43 then A calcium tungstate is CaWO4 B tungstic acid is H3WO4 C cesium tungstate is CsWO4 D tungsten hydride would be WH7 37 The acid formed when HCl gas is dissolved in water is called A hydrogen chloride B hydrogen chlorite C hydrogenchloric D hydrochloric 38 Tetrasulfur dinitride decomposes explosively when heated What is its formula A s4N4 B sZN4 C S4Nz D 4SN2 E SN8 39 Ferric oxide is used as a pigment in metal polishing Which of the following is its formula A Fe3O4 B FeO C Fe203 D FezO E Fe205 Bonding 40 In which compound does ionic bonding predominate A LiBr B CO C H20 D SiC 41 In which pair do both compounds exhibit predominantly ionic bonding A so2 and HCl B NaF and MgO C KNO3 and CH4 D KCl and co2 42 In which hydrogen compound is the bond essentially ionic A sodium hydride B methane C hydrogen chloride D hydrogen iodide E ammonia 43 Which pair of elements is most likely to react to form a covalently bonded species A P and O B Ca and O C K and S D Zn and Cl 44 Which chloride should exhibit the most covalent type of bond A NaCl B KCl C CaClz D BaClz E BeClz 45 Which of the following compounds is best described as covalent A PC13 B CaClz C MgO D CszS E none of these ANSWERS BCDDClCADDDlBADCDlACCEAlACCAElDDEAAlCCDBC ADCCAlBAAEAl CHEM 1331 CHAPTER 3 De nition ofMole 602 X 1023 De nition ofMolar Mass 1 mole of a substance weights the atomicmolecular mass in grams Important Equations moles grams molar mass Molecules 602 x 1023 x moles M olarity molarity moles of solute liters of solution Stoichiometry BALANCED EQUATIONS Relate relative numbers of moles of substances If 2 substances A and B have coefficients a and b Moles of B b a x moles of A ROADMAP STRESSES RELATIONSHIPS grams of A grams of B g g l n g MIVI l Pameles Moles of A Moles of B NA 4 23 11A 11B 23 N602X10 n nBbanA N602X10 n M n L 7 Volume of Volume of Solution L Solution L Limiting Reagents If given information about more than one reactant a calculate moles of B for each reactant individually b smaller number of moles of B comes from limiting reactant c use this number to nish problem Percent Yield Empirical Formula Percent by Mass Dilutions yield actual yield theoretical yield X 100 Calculate theoretical yield as above Have to do experiment to get actual yield Ratio of number of each type of atom Related to MOLECULAR FORMULA by whole number multiple Calculate from relative masses of elements For each element in substance a convert to moles b convert moles to nice numbers by dividing by smallest number c if necessary multiply ALL by 2 3 etc to clear fractions If given PERCENT of each element use percent as grams If not given one element subtract other masses from total sum For combustion of C H compounds or C H 0 compounds Sometimes given g of C02 and H20 Convert to g of C by multiplying C02 mass by 12 44 g of H by multiplying H20 mass by 2 18 From formula mass of element mass of element in 1 mole X 100 Molar mass of compound Diluting a solution Old molarity X old volume new molarity X new volume