Chapter 18—Spontaneous Change: How Fast?

MULTIPLE CHOICE

1. The reaction C12H22O11(s) + 12 O2(g) 12 CO2(g) + 11 H2O(l) is an example of a combustion

reaction. What is the rate of production of carbon dioxide relative to the rate of production of water?

a. Δ[CO2]/Δt = 12 Δ[H2O]/11 Δt

b. Δ[CO2]/Δt = 11 Δ[H2O]/12 Δt

c. Δ[CO2]/Δt = Δ[H2O]/11 Δt

d. Δ[CO2]/Δt = Δ[H2O]/12 Δt

ANS: A PTS: 1 REF: p. 721–725 BLM: Higher Order

2. In a reaction occurring in a solution, which of the following factors would NOT affect the rate of the

reaction?

a. the presence of a catalyst

b. the concentration of the reactants

c. the surface area of the solute in solution

d. the temperature of the solution

ANS: C PTS: 1 REF: p. 725 BLM: Higher Order

3. For the reaction CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l), what can be said about the

exponent(s) in the rate equation?

a. The exponent would be 1.

b. The exponents would be 1 and 2.

c. The exponents cannot be determined when the reaction involves different phases of

matter.

d. The exponents must be determined experimentally.

ANS: D PTS: 1 REF: p. 727 BLM: Higher Order

4. The rate law for a chemical reaction contains three main terms. Which of the following is NOT one of

the major terms?

a. the rate constant

b. the frequency factor

c. the concentrations of the species

d. the partial orders with respect to the reactants

ANS: B PTS: 1 REF: p. 727 BLM: Higher Order

5. How can the rate law for a chemical reaction be determined?

a. by looking at the stoichiometric coefficients

b. by comparing the reaction to another known reaction

c. by experiment

d. by changing one reactant at a time

ANS: C PTS: 1 REF: p. 727 BLM: Higher Order

13. What is the rate of reaction when [HSO5

–

] = [ClO2

–

] = 0.50 mol L–1

?

a. 1.2 x 10–2 mol L–1

s

–1

b. 9.0 x 10–3 mol L–1

s

–1

c. 6.0 x 10–3 mol L–1

s

–1

d. 3.0 x 10–3 mol L–1

s

–1

ANS: C PTS: 1 REF: p. 729–731 BLM: Higher Order

14. For a first-order reaction, A 3 B, the rate constant was found to be 7.6 x 10–4

s

–1

at 25 °C. If the

original concentration of A was 1.75 mol L–1

, what is the concentration of A after 1.00 min?

a. 1.62 mol L–1

b. 1.67 mol L–1

c. 1.70 mol L–1

d. 1.75 mol L–1

ANS: B PTS: 1 REF: p. 732 BLM: Higher Order

15. For a first-order reaction, A B, the rate constant was found to be 3.4 x 10–4

s

–1

at 23 °C. After 5.0 h,

the concentration of A was found to be 0.00018 mol L–1

. What was the original concentration of A?

a. 0.082 mol L–1

b. 0.0040 mol L–1

c. 0.00020 mol L–1

d. 0.00018 mol L–1

ANS: A PTS: 1 REF: p. 732 BLM: Higher Order

16. For a first-order reaction, A B + C, 15% of A was consumed after 10 min. How much of A was

consumed after 30 min?

a. 61%

b. 55%

c. 45%

d. 39%

ANS: D PTS: 2 REF: p. 732 BLM: Higher Order

17. For a first-order reaction, A 2 B, 75% of A remained after 42 s. If the original concentration of A

was 0.117 mol L–1

, what is the rate of the reaction in mol L–1

s

–1

after 2 min?

a. 3.5 x 10–4 mol L–1

s

–1

b. 6.0 x 10–4 mol L–1

s

–1

c. 8.0 x 10–4 mol L–1

s

–1

d. 6.8 x 10–3 mol L–1

s

–1

ANS: A PTS: 3 REF: p. 732 BLM: Higher Order

18. In a second order reaction, 2 A B, the rate constant was found to be 3.72 x 10–1 L mol–1 min–1

. If the

initial concentration of A was 0.82 mol L–1

, what was the concentration of A after 45 min?

a. 0 mol L–1

b. 4.4 x 10–8 mol L–1

c. 5.6 x 10–6 mol L–1

d. 1.4 x 101 mol L–1

ANS: C PTS: 1 REF: p. 733–734 BLM: Higher Order

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