[A] = [A]0 - kt
t1/2 = [A]0/2k
[A] = [A]0e-kt
ln[A] = ln[A]0 - kt
t1/2 = ln2/k
1/[A] = 1/[A]0 + kt
t1/2 = 1/k[A]0
lnk = lnA - Ea/RT
ln(k2/k1) = - (Ea/R)(1/T2 - 1/T1)
Kp = Kc(RT)Δn
ln(K2/K1) = - (ΔHo/R)(1/T2 - 1/T1)




1.
The compound RX3 decomposes according to the equation
RX3   →   R   +   R2X3      +   3X2
In an experiment the following data were collected for the decomposition at 100°C. What is the average rate of reaction over the entire experiment?
t(s)
[RX3](mol L-1)
0
0.85
6
0.41
12
0.20
14
0.16
 
A.
0.011 mol L-1s-1
B.
0.019 mol L-1s-1
C.
0.044 mol L-1s-1
D.
0.049 mol L-1s-1
E.
0.069 mol L-1s-1


2.
For the reaction
3A(g)   +   2B(g)   →   2C(g)   +   2D(g)
the following data were collected at constant temperature. Determine the correct rate law for this reaction.
Trial
Initial [A]
Initial [B]
Initial Rate
     
(mol/L)
(mol/L)
(mol/(L·min))
1
0.200
0.100
6.00 × 10-2
2
0.100
0.100
1.50 × 10-2
3
0.200
0.200
1.20 × 10-1
 
A.
Rate = k[A][B]
B.
Rate = k[A][B]2
C.
Rate = k[A]3[B]2
D.
Rate = k[A]1.5[B]
E.
Rate = k[A]2[B]


3.
When the reaction A   →   B   +   C is studied, a plot 1/[A] vs. time gives a straight line with a positive slope. What is the the order of the reaction?
A.
zero
B.
first
C.
second
D.
third
E.
More information is needed to determine the order.


4.
Which of the following sets of units could be appropriate for a zero-order rate constant?
A.
s-1
B.
L mol-1 s-1
C.
L2 mol-2 s-1
D.
L3 mol-3 s-1
E.
mol L-1 s-1


5.
The rate law for the reaction 3A → 2B is rate = k[A] with a rate constant of 0.0447 hr-1. What is the half-life of the reaction?
A.
0.0224 hr
B.
0.0645 hr
C.
15.5 hr
D.
22.4 hr
E.
44.7 hr


6.
Butadiene, C4H6, dimerizes to C8H12 with a rate law rate = k[C4H6]2 where k = 0.84 L/(mol·min). What will be the concentration of C4H6 after 180 min if its initial concentration is 0.025 M?
A.
0.0052 M
B.
0.024 M
C.
43 M
D.
190 M
E.
0.000077 M


7.
The decomposition of SOCl2 is first-order in SOCl2. If the half-life for the reaction is 4.1 hr, how long would it take for the concentration of SOCl2 to drop from 0.36 M to 0.045 M?
A.
0.52 hr
B.
1.4 hr
C.
12 hr
D.
33 hr
E.
> 40 hr


8.
The decomposition of dinitrogen pentaoxide has an activation energy of 102 kJ/mol and ΔH°rxn = + 55 kJ/mol. What is the activation energy for the reverse reaction?
A.
27 kJ/mol
B.
47 kJ/mol
C.
55 kJ/mol
D.
102 kJ/mol
E.
157 kJ/mol


9.
Consider the following mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous acid solution.
H+   +   H2O2   ↔     H3O2+          (rapid equilibrium)
H3O2+   +   Br-   → HOBr   +   H2O       (slow)
HOBr   +   H+   +   Br-   →    Br2   +   H2O    (fast)
Which of the following rate laws is consistent with the mechanism?
A.
Rate = k[H2O2][H+]2[Br-]
B.
Rate = k [H2O2][H+]
C.
Rate = k[H2O2][H+][Br-]
D.
Rate = k[HOBr][H+][Br-][H2O2]
E.
Rate = k[Br-]


10.
When a catalyst is added to a reaction mixture, it
A.
increases the rate of collisions between reactant molecules.
B.
provides reactant molecules with more energy.
C.
slows down the rate of the back reaction.
D.
provides a new pathway (mechanism) for the reaction.
E.
does none of the above.


11.
Which of the following has an effect on the magnitude of the equilibrium constant?
A.
partial pressures of the reactants
B.
concentrations of the reactants and products
C.
presence of a catalyst
D.
change in volume of container
E.
change in temperature


12.
Write the mass-action expression, Qc , for the following chemical reaction.
2Cu2+(aq)   +   4I-(aq)   ↔   2CuI(s)   +   I2(aq)
A.
B.
C.
D.
E.


13.
The equilibrium constant, Kc , for the decomposition of COBr2
COBr2(g)   ↔   CO(g)   +   Br2(g)
is 0.190. What is Kc for the following reaction?
2CO(g)   +   2Br2(g)   ↔   2COBr2(g)
A.
0.0361
B.
2.63
C.
5.62
D.
10.5
E.
27.7


14.
The reaction of nitrogen with oxygen to form nitric oxide can be represented by the following equation.
N2(g)   +   O2(g)   ↔   2NO(g)         R = 0.08206 L·atm/mol·K
At 2000°C, the equilibrium constant, Kc , has a value of 4.10 × 10-4. What is the value of Kp?
A.
2.17 × 10-8
B.
4.10 × 10-4
C.
7.65 × 10-2
D.
7.75
E.
2.17 × 10-4


15.
The equilibrium constant, Kp , for the reaction
H2(g) + I2(g) ↔   2HI(g)
is 55.2 at 425°C. A rigid cylinder at that temperature contains 0.127 atm of hydrogen, 0.134 atm of iodine, and 1.055 atm of hydrogen iodide. Is the system at equilibrium?
A.
Yes.
B.
No, the forward reaction must proceed to establish equilibrium.
C.
No, the reverse reaction must proceed to establish equilibrium.
D.
Need to know the volume of the container before deciding.
E.
Need to know the starting concentrations of all substances before deciding.


16.
Compounds A, B, and C react according to the following equation.
3A(g)   +   2B(g)   ↔   2C(g)
At 100°C a mixture of these gases at equilibrium showed that [A] = 0.855 M, [B] = 1.23 M, and [C] = 1.75 M. What is the value of Kc for this reaction?
A.
0.309
B.
0.601
C.
1.66
D.
3.24
E.
> 10


17.
At 25°C, the equilibrium constant Kc for the reaction
2A(aq)   ↔   B(aq)   +   C(aq)
is 65. If 2.50 mol of A is added to enough water to prepare 1.00 L of solution, what will the equilibrium concentration of A be?
A.
0.038 M
B.
0.15 M
C.
0.28 M
D.
1.18 M
E.
2.4 M


18.
Ammonium iodide dissociates reversibly to ammonia and hydrogen iodide.
NH4I(s)   ↔   NH3(g)   +   HI(g)
At 400°C, Kp = 0.215. Calculate the partial pressure of ammonia at equilibrium when a sufficient quantity of ammonium iodide is heated to 400°C.
A.
0.103 atm
B.
0.215 atm
C.
0.232 atm
D.
0.464 atm
E.
2.00 atm


19.
Methanol can be synthesized by combining carbon monoxide and hydrogen.
CO(g)   +   2H2(g)   ↔   CH3OH(g)
A reaction vessel contains the three gases at equilibrium with a total pressure of 1.00 atm. What will happen to the partial pressure of hydrogen if enough argon is added to raise the total pressure to 1.4 atm?
A.
The partial pressure of hydrogen will decrease.
B.
The partial pressure of hydrogen will increase.
C.
The partial pressure of hydrogen will be unchanged.
D.
Kp needs to be known before a prediction can be made.
E.
Both Kp and the temperature need to be known before a prediction can be made.


20.
Nitrogen dioxide can dissociate to nitric oxide and oxygen.
2NO2(g)   ↔   2NO(g)   +   O2(g)       ΔH°rxn = +114 kJ
Under which reaction conditions would you expect to produce the largest amount of oxygen?
A.
high temperature, high pressure
B.
low temperature, high pressure
C.
high temperature, low pressure
D.
low temperature, low pressure
E.
presence of a catalyst


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