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1) What is the equation for determining relative rates?
2) Which of the following is a buffer?
a. KCl and water
b. KNO3 and HNO3
c. NaF and HF
d. HBr and CaBr2
3) Which is the strongest acid:
a. HClO
b. HClO2
c. HClO3
d. HClO4
4) 8A + 4B + C ↔ 5D + 2E
Write the equilibrium constant expression.
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5) For N2(g) + 3H2(g) ↔ 2 NH3(g), Kp = 4.34*10-3 at 300°C. What is the value of Kp
for the reverse reaction?
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a. Kp doesn’t change for reverse processes
b.
c.
d.
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230
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5.31 * 10
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8.68 * 10
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4
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Supplemental Instruction
1060 Hixson-Lied Student Success Center v 294-6624 v www.si.iastate.edu
6) A sample of NOBr decomposes according to the equation:
2 NOBr(g) ↔ 2 NO(g) + Br2(g)
An equilibrium mixture in a 5.00 L vessel at 100 C contains 3.22 g NOBr, 3.08 g NO,
and 4.19 g Br2. Calculate Kc
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a. Kc = 0.0184
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K = 14.9
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K = 0.0165
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b. Kc = 0.0648
c.
d.
c
c
7) How do the following changes affect an equilibrium reaction of the following (the
reaction is exothermic):
2 CH3CH3(g) + 5 O2(g) ↔ 6 H2O(l) + 2 CO2(g)
Increasing [O2], decreasing volume of container, increase temperature
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a.
b.
c.
d.
Shift right, shift right, shift left
Shift right, shift right, shift right
Shift left, shift right, shift right
Shift right, shift left, shift right
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8) At the start of a certain reaction, only reactants are present, products have not been
formed yet. What is the value of Q at this time?
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a.
b.
c.
d.
Q>0
Q=0
Q<0
Q=K
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Will Q at this point be greater or less than K?
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9) Calculate the concentration of OH-(aq) in a solution in which [H+] = 100*[OH-]
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a.
b.
c.
d.
0.010 M
10-8 M
10-6 M
0.001 M
What is the pOH of this solution? What is the pH?
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10) Calculate the concentration of C6H5COONa that must be present in a 0.20 M solution
of benzoic acid to produce a pH of 4.00. Ka = 6.3 * 10-5
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a.
b.
c.
d.
[CH3COONa] = 0.00010 M
[CH3COONa] = 0.13 M
[CH3COONa] = 7.7 M
[CH3COONa] = 0.36 M
11) It is found that 1.1*10-2 g of SrF2 dissolves per 100 mL of aqueous solution at 25°C.
Calculate Ksp for this solution.
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a.
b.
c.
d.
4.43*10-9
2.7*10-9
6.65*10-10
1.0*10-7
9.) The conversion of oxygen gas to ozone can follow a three-step mechanism listed below: Rate Law:
Molecularity:
___ O2 + ___ NO —> ___ NO2
______ —> ___ NO + ___ O
___ O2 + ___ O —> ______
(a)
(6 pts) Write down the rate law for each step, and identify the molecularity of each step. (b) (1 pt) Write
the complete balanced net chemical reaction.
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(c) (2 pts) In this mechanism, identify any intermediates and any catalysts.
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3. (3 pts) The rate law for the uncatalysed reaction NO2(g) + CO(g) —-> NO(g) + CO2(g) is rate
= k[NO2]2. Write a mechanism that may account for this reaction and its rate law. In your
mechanism, identify any intermediates (The first step is the slow step).
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12) The decomposition of a certain insecticide in water at 12°C follows first-order
kinetics with k = 1.45 yr-1. How long does it take for the concentration to reach ¼ of
its initial concentration?
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a.
b.
c.
d.
0.856 yrs
0.568 yrs
0.956 yrs
0.582 yrs
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13) Consider the gas-phase reaction between nitric acid and bromine at 273 °C:
2 NO(g) + Br2(g) → 2 NOBr(g)
The following data for the initial rate of appearance of NOBr were obtained.
Calculate the rate constant.
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a.
b.
c.
d.
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$
1200 M-1s-1
12000 M-2s-2
6000 M-1s-2
Cannot calculate with the given data
14) Is a spontaneous process reversible?
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a.
b.
c.
d.
Yes, always
No, only if ΔG < 0
No, always
Yes, if ΔSuniv < 0
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15) Calculate ΔS° for the following reactions:
Be(OH)2(s) → BeO(s) + H2O(g)
S°(J/K):
50.21
13.77
188.83
a.
b.
c.
d.
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253 J/K
152 J/K
-225 J/K
-253 J/K
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16) Consider the reaction
PbCO3(s) ↔ PbO(s) + CO2(g)
ΔH°(kJ)
-699.1
-217.3
-393.5
ΔS°(J/K)
131.0
68.70
213.6
Calculate the equilibrium pressure of CO2 in the system at 400 °C
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17) For the redox reaction:
Mn2+(aq) + NaBiO3(s) → Bi3+(aq) + MnO4-(aq)
Write the oxidation half-reaction for the reaction above.
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a. 2 H2O(l) + 2 Mn2+(aq) → 4 MnO4-(aq) + 8 H+(aq)
b.
c.
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2 H O(l) + 2 Mn
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2 H O(l) + 2 Mn
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2
2+(aq)
→ 4 MnO4-(aq) + 8 H+(aq) + 2 e-
2
2+(aq)
→ 4 MnO4-(aq) + 8 H+(aq) + 5e-
d. 4 H2O(l) + Mn2+(aq) → MnO4-(aq) + 8 H+(aq) + 5e-
18) A voltaic cell utilizes the following reaction and operates at 298 K:
3 Ce4+(aq) + Cr(s) → 3 Ce3+(aq) + Cr3+(aq)
What is the emf of this cell under standard conditions?
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a.
b.
c.
d.
0.87 V
-2.35 V
-0.87 V
2.35 V
19) Elemental calcium is produced by the electrolysis of molten CaCl2. What mass of
calcium can be produced by this process if 7.5*103 A is flowing for 48 hour period?
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a.
b.
c.
d.
168 g
2.69*105 g
4.78*10-3 g
269 g
20) What particle is released during the decay of sodium-24 into magnesium-24.
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a.
b.
c.
d.
Alpha particle
Beta particle
Gamma particle
Neutron
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21) Cobalt-60 which undergoes beta decay, has a half-life of 5.26 yrs. How many beta
particles are emitted in 600 s by a 3.75 mg sample of 60Co?
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Tf = kfm
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Formulas:
kf = 1.86 °C/m for H2O(l)
For first order processes, half-life, t1/2 =
kN
Δ(G,H,S,)° =
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ΔG = ΔG° + RTlnQ
°red(anode)
ΔG° = ΔH°-TΔS°
pH = -log[H+]
Ka*Kb = Kw
ln[A] = -kt + ln[A0] Rate =
E°cell = E°red(cathode) – E