Name ____________________________________ General Chemistry II
Sample Exam
Chapter 14 Sample Problems
1. In the reaction H2O2(aq) → H2O(l) + 0.5O2(g), the initial concentration of H2O2 is 0.2546 M, and the initial rate of
reaction is 9.32 10-4 M s-1. What will be [H2O2] at t = 35 s?
2. For the gas phase decomposition of hydrogen iodide at 700 K 2 HI(g) →H2(g) + I2(g) the average rate of disappearance
of HI over the time period from t = 0 s to t = 797 s is found to be 5.28 x 10-4 M/s. What is the average rate of appearance
of H2 over the same time period?
3. A reaction has the rate law Rate = k[A][B]2. What is the order of the reaction?
4. In the first-order decomposition of dinitrogen pentoxide at 335 K,
N2O5(g) → 2NO2(g) + 0.5O2(g)
if we start with a 2.50 g sample of N2O5 at 335 K and have 1.50 g remaining after 109 s, (a) What is the value of the
rate constant k? (b) What is the half-life of the reaction? (c) What mass of N2O5 will remain after 5.0 min?
5. The decomposition of hydrogen iodide on a gold surface at 150C: HI(g) ⇄ H2(g) + I2(g) is zero order in HI with a
rate constant of 1.20 x 10-4 Ms-1. If the initial concentration of HI is 0.110 M, what is the concentration of HI after
776 seconds have passed
6. A general reaction is the formation of molecule C from two reactant molecules, A and B.
A + B → C
The reaction was run multiple times at constant temperature using different initial concentrations of the two reactants.
The initial rates obtained are included in the table below.
[A], mol/L [B], mol/L rate, mol/(L-min)
Trial 1 0.350 0.880 0.180
Trial 2 0.770 0.880 0.360
Trial 3 0.350 1.76 0.360
Trial 4 0.967 0.651 0.368
What is the reaction order with respect to A? What is the reaction order with respect to B? Determine the rate
equation and the value of the rate constant.
7. The rate of the reaction between CO and NO2 at 540 K
CO(g) + NO2(g) →CO2(g) + NO(g)
was measured starting with various concentrations of CO and NO2.
[CO], mol/L [NO2], mol/L rate, mol/(L-min)
Trial 1 5.10 x 10-4 3.50 x 10-5 3.4 x 10-8
Trial 2 5.10 x 10-4 7.00 x 10-5 6.8 x 10-8
Trial 3 5.10 x 10-4 1.75 x 10-5 1.7 x 10-8
Trial 4 1.02 x 10-3 3.50 x 10-5 6.8 x 10-8
Trial 5 1.53 x 10-3 3.50 x 10-5 10.2 x 10-8
What is the reaction order with respect to A? What is the reaction order with respect to B? Determine the rate
equation and the value of the rate constant.
8. Rate constants for the first-order decomposition of acetonedicarboxylic acid
CO(CH2COOH)2(aq) → CO(CH3)2(aq) + 2 CO2(g)
are k = 4.75 x 10-4 s-1 at 293 K and k = 1.63 x10-3 s-1 at 303 K. What is the activation energy, Ea, for this reaction?
9. The gas phase decomposition of hydrogen peroxide at 400 C
H2O2 (g) → H2O(g) + O2(g)
is second order in H2O2 with a rate constant of 0.650 M
-1 s-1. If the initial concentration of H2O2 is 0.118 M, the
concentration of H2O2 will be M after 56.7 seconds have passed.
10. In a study of the decomposition of ammonia on a platinum surface at 856 C
NH3 → 1/2 N2 + 3/2 H2
the...
