Multiple Choice
1 / A / O=C=O, one bond to each O is s and the other is p.2 / C / Dipole moment depends on electronegativity difference, which relates to distance between atoms.
3 / D / PH3 has a pair of electrons around the P, which pushes the H's downward making a pyramidal shape.
4 / C / C contains 5 valence electrons (2s22p3), A, B and C contain 2 valence electrons.
5 / A / All electrons are paired.
6 / D / Transition metals valence electrons in the s sublevel only plus d level electrons.
7 / B / Solid and liquid are in equilibrium at the melting point (the lower plateau).
8 / C / Melting and boiling occur at the plateaus \ the answer is between the two plateaus.
9 / C / PCH4 = XPtot = (0.90/1.5)3.0 atm = 1.8 atm
10 / B / Hydrogen bonding occurs between molecules, which have a N, O or F bonded to H.
11 / D / The strength of dispersion forces depends on the number of polarizable electrons.
12 / A / Gases deviate from ideal behavior at low temperature (clumping) and high pressure (particle volume).
13 / B / 10 g ® 5 g ® 2.5 g \ 2 t½ = 195 days (t½ = 97.5 days).
14 / C / The biggest gap in energy occurs after the 4th electron \ 4 valence electrons.
15 / C / 3920Ca ® 3921Sc + 0-1b
16 / D / 1 mol Ar at STP occupies 22.4 L. With half the volume, the temperature must be halved standard = ½ x 273.
17 / A / DTb = Kbmi: AlCl3 has the greatest value for i = 4.
18 / D / Molarity = mol/VL: The mass is needed to determine moles RbCl and the volume for the denominator.
19 / A / Covalent bonds are broken when melting a covalent network solid. (SiO2 temp. rises during melting)
20 / B / O–O=O: The bond order is 3/2 or 1.5.
21 / C / Cl < S because of greater effective nuclear charge and S < S2- because S2- has more electrons.
22 / D / Se is in the same column as S and has the same number of valence electrons \ similar properties..
23 / D / v = (3RT/MM)½ \ the lightest molecule would be the fastest \ HCN.
24 / D / H3C–CH=CH2
sp3 sp2 sp2
25 / C / Covalent bonds are broken during a phase change for covalent network solids only \ graphite.
26 / D / 0.500 L x 0.200 mol/L x 119 g/mol = 11.9 g
27 / D / 500 kJ x 1 mol/26 kJ x 128 g/mol = 2500 g
28 / D / CH3OCH3(g) + 3 O2(g) ® 2 CO2(g) + 3 H2O(g)
29 / D / 0.50 mol Cu2O has 1 mol Cu x 64 g/mol = 64 g.
30 / A / Ketones have a double bonded oxygen on an interior carbon.
31 / C / C2H4 has the highest % C (24/28) compared to the other molecules.
32 / D / Reduction occurs at the cathode Fe3+ + 1 e- ® Fe2+
(Zn is oxidized at the anode).
33 / C / Eo = Eored + Eoox = 0.77 V + 0.76 V = 1.53 V
34 / D / 2 Fe3+ + Zn ® 2 Fe2+ + Zn2+: Fe3+ is reduced \ Fe3+ is the oxidizing agent.
35 / D / The reaction doesn't occur because it takes too much energy to reach the activated state \ Ea is too large.
36 / B / Tthreshold = DH/DS
400 K = DH/0.050 kJ mol-1 K-1 \ DH = -20 kJ mol-1
37 / D / 2 Au3+ + 6 I- ® 2 Au(s) + 3 I2(s)
38 / D / Volumetric flask and pipet have the greatest accuracy and the volumetric flask is the exact volume needed.
39 / B / Second order reactions produce straight line graphs of 1/[Z] vs. t.
40 / B / 0.60 mol CS2 x 2 mol SO2/1 mol CS2 = 1.2 mol SO2
1.5 mol O2 x 2 mol SO2/3 mol O2 = 1.0 mol SO2
41 / A / DHfus is the heat lost by the warm water ¸ by the moles of ice melted. The difference in mass = massice.
42 / C / The mass of ice would be too large, which would make moles to large and DHfus too small.
43 / D / 243 g Mg x 2 mol e-/24.3 g = 20 mol e-
20 mol e- x 1 mol Al/3 mol e- x 27 g Al/1 mol Al = 180 g
44 / A / 20 g x 1 mol/1 g = 20 mol H x 3 = 60 mol H \ CH3
80 g x 1 mol/12 g = 6.7 mol C x 3 = 20 mol C
45 / C / At the threshold temperature, DG = 0.
46 / B / Equal volumes will produce a solution with a concentration half way between the two.
47 / C / +1 +1 -2 +1 +7 -8
HClO: H Cl O, HClO4: H Cl O
48 / A / The greatest surface area allows for more collisions between air molecules and wood molecules.
49 / B / 0.1 mol S8 x 8 mol H2S/1 mol S8 x 22.4 L/mol = 20 L
50 / C / Forming bonds is an exothermic process.
51 / B / Precipitation reaction occurs when ions combine to form a solid ionic product (precipitate).
52 / C / A complex ion = transition metal ion + ligands. In [Zn(OH)4]2-, metal ion is Zn2+ and ligand is OH-.
53 / C / Lewis A-B: electron pair acceptor (Zn(OH)2) is acid and electron pair donor (OH-) is base ® one product.
54 / B / Ka = [H+]2/[HA] ® [H+] = (Ka[HA])½
[H+] = [(2.5 x 10-6)(0.40)]½ = (1 x 10-6)½ = 1 x 10-3 \ pH = 3
55 / D / Increasing pressure favors the fewer gas molecules. (a) & (b) shift to the right and (c) is not affected .
56 / B / pOH = 14 – pH = 14 – 11.50 = 2.50
[OH-] = 10-2.50, which is between 10-2 and 10-3.
57 / C / Only temp. changes K. The other changes can change the equilibrium position (® or ¬), but not K.
58 / D / Temperature favors endothermic, which is ®, the rates of both reactions (¬ and ® )are increased.
59 / D / F-/HF is a conjugate pair, with F- as a base. H2O/OH- is also a conjugate pair, with OH- as a base.
60 / C / pOH = 5 \ [OH-] = 1E-5 ® s = ½[OH-] = ½(1E-5) = 5E-6
M(OH)2 D M2+ + 2OH- \ Ksp = 4s3 = 4(5E-6)3 = 5 x 10-16
61 / B / 0.05 mol x 0.40 = 0.02 mol X2+ and 0.04 mol Y-
0.05 mol – 0.02 mol = 0.03 mol XY2 \ 0.09 mol total
62 / D / Best indicator changes color at equivalence (where the line is most vertical (pH = 9) \ phenolphthalein.
63 / D / Best indicator changes color at equivalence (where the line is most vertical (pH = 9) \ phenolphthalein.
64 / A / Optimum buffer has a 50-50 mixture of acid and conjugate base, which is at the half titration point.
65 / A / Shifting to the right will increase [CO32-]/[HCO3-]. This is done by decreasing T since reaction is exothermic.
66 / A / Sulfur has 4 p electrons (¯)( )( ), two of which are unpaired.
67 / C / Ga is in column 13, which has one p electron.
68 / C / CH2=CH2. CO2 has two double bonds, and H2O and PH3 have only single bonds.
69 / B / H2O and PH3 are the only polar molecules. H2O has a greater electronegativity difference.
70 / D / PH3 has a pair of electrons around P, which pushes the H's down forming a trigonal pyramidal shape.
71 / C / KMnO4, an important oxidizing agent, is purple.
72 / D / All column 1 metals form soluble salts. KMnO4 is purple. FeCl3 is soluble but yellow.
73 / D / v = (3RT/MM)½ \ the gas with a molar mass closest to 28 would have the same velocity.
74 / B / The volumes are the same for all gases, so the one with the greatest MM would be most dense.
75 / A / Rate » v = (3RT/MM)½ \ the gas with the smallest MM would have the greatest rate.
76 / C / A precipitation reactions are:
cation + anion ® insoluble ionic compound.
77 / D / Complex ions contain a transition metal cation surrounded by ligands, which has a overall charge.
78 / B / One element shows up in two products with different oxidation states.
79 / A / Combustion is a general term for redox reaction where oxygen gas is reduced.
80 / B / Freezing occurs at the lower plateau (boiling occurs at the higher plateau.
81 / A / Boiling is occurring during second plateau, where liquid molecules are entering the gas phase.
82 / A / Isoelectric series includes elements that are within three squares of a noble gas.
83 / B / This is a proton exchange reaction, where NH3 receives H+ forming the conjugate acid NH4+.
84 / D / Below triple point the solid goes directly to a gas (sublimation) at 20o C.
85 / D / The oxidation number for S in H2SO4 is +6, which is the same for SO2Cl2 (S + 2(-2) + 2(-1) = 0).
86 / D / SO2(g) is 1/5 the total moles \ 1/5 the total pressure (800/5 = 160 mm Hg).
87 / B / H2(g) is produced when strong acid (HCl) is added to metal with a negative Eored.
88 / D / A = 235 + 1 – (141 + 3 + x) \ x = 92
Z = 92 + 0 – (55 + 0 + y) \ y = 37 \ nuclide is 9237Rb
89 / C / The mole ratio in the compound is 2 K + 1 Te + 3 O \ the formula is K2TeO3.
90 / A / DHo = DHfoC6H6 –3 DHfoC2H2 = 83 – 3(230) = -607 kJ
91 / B / 0.250 L x 0.10 mol/L x 250 g/mol = 6.25 g
92 / A / The rate is based on the slow step, where reactant coefficients become exponents \ Rate = k[NO]2.
93 / D / Most ionic compounds are composed of a metal cation and a non-metal anion.
94 / C / pH = 8 \ pOH = 14 – 8 = 6 and [OH-] = 1 x 10-6 M
95 / C / Diamonds are covalent network solids where carbon atoms are bonded covalently to each other.
96 / A / At common temperature and pressure, moles of gas are directly proportional to moles \ 4 L CO2 = 12 L O2.
97 / B / Molecular substances are gases, which are composed of nonmetals, but not SiO2 (covalent network).
98 / D / Indicator changes color at equivalence, which occurs during vertical section of graph \ pH = 9.
99 / A / Buffer action occurs when acid and conjugate base have equal concentration (plateau section) \ V.
100 / A / Adding solute raises boiling pt. and osmotic pressure, but lowers vapor pressure and freezing pt.
101 / B / The yellow ppt. indicates Pb2+. Dissolving the precipitate with NH3 indicates Ag+.
102 / A / Using Le Chatelier's principle, lowering the exothermic reaction temperature will shift to right.
103 / D / Na2SO4 has a van't Hoff factor of 3, where NaCl has a factor of 2 \ Na2SO4 produces more moles of ions.
104 / B / KNO3 has the greatest change in solubility between 90oC and 30oC \ a higher % precipitates at lower T.
105 / D / .1 L x .4 mol H+/L x 1 mol H2/2 mol H+ x 22.4 L/mol H2 = 0.448 L = 448 mL
106 / C / Reaction happens \ DG < 0, Temperature drops \ DH > 0, Gas is produced \ DS > 0.
107 / B / K for the reverse reaction is 1/K for the forward reaction \ (2.0 x 105)-1 = 5.0 x 10-6.
108 / D / 63.55 = 63(1 – x) + 65(x) = 63 – 63x + 65x = 63 + 2x
0.55 = 2x \ x » 0.25
109 / D / Atomic radius decreases because each element in a period gains a proton w/o increasing core electrons.
110 / A / mol ethanol = 46 g x 1 mol/46 g = 1 mol
mol H2O = 54 g x 1 mol/18 g = 3 mol \ 1/(1 + 3) = 0.25
111 / D / Cr2O72- + 14 H+ + 6e- ® 2 Cr3+ + 7 H2O
3(H2S ® S + 2 H+ + 2 e-)
Cr2O72- + 8 H+ + 3 H2S ® 2 Cr3+ + 7 H2O + 3 S
112 / B / The effective nuclear charge for Na is lower, which results in a weaker attraction for valence electrons.
113 / C / Reaction order is determined from experiment because it depends on the slow step in a mechanism.
114 / B / Ionic compounds are soluble in polar solvents. CCl4 is nonpolar.
115 / C / Adding solid acid to distilled water is necessary for titration because the acid has to be in solution.
116 / B / NO3-: N + 3(-2) = -1 \ N = +5
NO: N + (-2) = 0 \ N = +2
117 / B / C3H8 + 5 O2 ® 3 CO2 + 4 H2O
118 / D / Ea for forward and reverse reactions are equal then DE between reactants and products = 0.
119 / A / Only first order reactions have a constant half life, which is 3 days for this substance.
120 / D / Unshared pairs of electrons take up more space, which leaves less space for H and a tighter angle.
121 / A / Higher boiling pt. is due to stronger intermolecular bonds—dispersion forces, which increase with MM.
122 / D / The concentration of M and N are both doubled. M is 1st order and N is 2nd order \ rate is 2 x 4 = 8 x faster.
123 / A / N2H4: 8 g x 1 mol/32 g x 4 mol H2O/2 mol = 0.5 mol
N2O4: 92 g x 1 mol/92 g x 4 mol H2O/1 mol = 4 mol
\ 0.5 mol H2O x 18 g/mol = 9 g.
124 / A / All are diatomic (all have odor and color, only F2 and Cl2 are gases).
125 / A / .02 L x .2 mol MnO4-/L x 3 mol ClO2-/4 mol MnO4- = 0.0030
126 / C / pH 12 is 1/10 as concentrated as pH 13 \ dilute the solution to 10 x the volume (1 liter).
127 / C / All Na+, K+ and NO3- salts are soluble.
128 / C / Same number and kinds of atoms, but the Br is on the middle carbon. (A, B and D are 1-bromopropane)
129 / B / Buffer requires a weak acid and its conjugate (HCl and HBr are strong acids).
130 / D / Small K2 means very few molecules have both H+ removed.
131 / C / 4 g/2 L x 22.4 L/1 mol = 44.8 g/mol \ CO2
132 / B / Phase change involves intermolecular bonds, which are H-bonds for water.
133 / A / 0.60 M Mg2+ x 200 mL/600 mL = 0.20 M Mg
134 / C / SiO2 is covalent network, which contains covalent bonds throughout. The others are all molecular.
135 / B / .200 F x 1 mol e-/1 F x 1 mol Ni2+/2 mol e- x 58.7 g/mol = 5.87 g
136 / C / Melting occurs along the plateau.
137 / C / H+ reacts with CO32-. NH3 precipitates with Al3+ (forms OH- ppt.), SO42- precipitates with Ba2+.
138 / D / At its normal melting point DG = 0 = DH – TDS
\ DH = TDS
139 / B / CO32- + 2 H+ ® H2O + CO2(g)
CO32- + H2O D HCO3- + OH- (basic solution)
140 / A / Ksp = [Zn2+][OH-]2 = (1.0 x 10-6)(2.0 x 10-6)2 = 4.0 x 10-18
141 / A / Noble gases are the least able to lose electrons (oxidation) in their period.
142 / D / High atomic mass atoms (# > 82) tend to be radioactive.
143 / C / Halogens pick up electrons and become anions.
144 / C / Equal moles of acid and base occur at equivalence, which is midpoint along vertical.
145 / D / Adding more base raises pH closer to pure base.
146 / B / Buffer is formed with equal concentration of acid and conjugate, which is along flat section.
147 / A / NH3 has a trigonal pyramid shape.
148 / D / HBr is a strong acid = strong electrolyte.
149 / D / Large molecules (HBr) have slow effusion rates (escape a small opening).
150 / C / Entropy (S) is zero when motion stops (0 K).
151 / A / ln(k1/k2) = (Ea/R)(1/T2 – 1/T1): Ea is determined using the reaction rates (µ k) and T.
152 / C / Lower energy (DH < 0), greater disorder (DS > 0).