Unformatted text preview: Final Examination Spring
Name___________________________________ R.Lopez de la
Bubble in the form number in the section entitled Grade or Educ in the scantron.
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) Molecular hydrogen can be made from methane gas by the reaction below. How is the rate of
disappearance of CH4 related to the rate of appearance of H2? = ?
CH4 (g) + H2O (l) → CO (g) + 3H2 (g)
A) + B) + 3 Δt
Δt C) + 1Δ [H2]
3 Δt D) none of these 2) Methanol can be produced by the following reaction:
CO(g) + 2 H2(g) → CH 3OH(g).
How is the rate of disappearance of hydrogen gas related to the rate of appearance of
- = ?
A) + 1Δ[CH3OH]
2 Δt B) + Δ [H4]
Δt C) + 2 Δ[CH3OH]
Δt 1) 2) D) none of these 3) The decomposition of dinitrogen pentoxide is described by the chemical equation
2 N2O5(g) → 4 NO 2(g) + O2(g)
If the rate of appearance of O2 is equal to 2.40 mol/min at a particular moment, what is the
rate of disappearance of N2O5 at that moment?
A) 9.60 mol/min
B) 0.600 mol/min
C) 1.20 mol/min
D) 4.80 mol/min 3) 4) The following set of data was obtained by the method of initial rates for the reaction: 4) 2 HgCl2(aq) + C2O42-(aq) → 2 Cl-(aq) + 2 CO 2(g) + Hg2Cl2(s)
What is the value of the rate constant, k? [HgCl2], M [C2O42-], M Rate, M/s
1.3 × 10-7
5.2 × 10-7
1.0 × 10-6
A) 1.3 × 10-4 1/M2·s
C) 1.3 × 10-7 1/M2·s B) 1.4 × 10-8 1/M2·s
D) 1.4 × 10-5 1/M2·s 1 5) The first-order reaction, 2 N2O(g) → 2 N2(g) + O2(g), has a rate constant equal to 0.76 s -1 at
1000 K. How long will it take for the concentration of N2O to decrease to 42% of its initial
A) 1.1 s
B) 1.8 s
C) 2.4 s
D) 0.88 s 5) 6) In aqueous solution, hypobromite ion, BrO -, reacts to produce bromate ion, BrO3-, and
bromide ion, Br-, according to the following chemical equation.
3 BrO-(aq) → BrO3-(aq) + 2 Br-(aq) 6) A plot of 1/[BrO-] vs. time is linear and the slope is equal to 0.056 M-1s-1. If the initial
concentration of BrO- is 0.80 M, how long will it take one-half of the BrO- ion to react?
A) 4.5 × 10-2 s
B) 12 s
C) 7.1 s
D) 22 s
7) The rate constant, k, for a first-order reaction is equal to 4.2 × 10-4 s -1. What is the half-life for
A) 2.9 × 10-4 s
B) 2.4 × 103 s
C) 1.2 × 103s
D) 1.7 × 103 s 7) 8) The following set of data was obtained by the method of initial rates for the reaction:
(H3C)3CBr + OH- → (H3C)3COH + Br- 8) What is the order of reaction with respect to ion, OH-? [(H3C)3CBr], M [OH-], M Initial Rate, M/s
1.1 × 10-4
2.2 × 10-4
2.2 × 10-4
C) second D) none of these 9) Chlorine reacts with chloroform according to the reaction given below:
Cl2 + CHCl 3 → CCl4 + HCl
When the initial concentration of Cl2 is doubled the reaction rate increases by a factor of 1.41.
What is the order of the reaction with respect to Cl2?
D) 2 9) 10) The hydrolysis of tert-butyl chloride is given in the reaction below:
(CH3)3CCl(aq) + H2O(l) → (CH3)3COH(aq) + H+(aq) + Cl-(aq)
If the rate law is: Rate = k[(CH3)3CCl], what is the order of the reaction with respect to water?
D) third 10) 11) For the zeroth-order reaction: C → products, -Δ[C]/Δt = k, which of the following graphs
would be expected to give a straight line?
A) [C] vs. t
B) ln[C] vs. t
C) [C] 2 vs. t
D) 1/[C] vs. t 11) 12) If the units for rate are M s-1, what are the units for the rate constant, k, for a zeroth-order
A) M s-1
B) M-1 s -1
D) M-1 12) 2 13) Which statement below regarding the half-life of a second-order reaction is true?
A) Each half-life is twice as long as the preceding one.
B) Each half-life is half as long as the preceding one.
C) Each half-life is four times as long as the preceding one.
D) The length of the half-life remains unchanged throughout the course of the reaction. 13) 14) Nitrogen dioxide decomposes at 300°C via a second-order process to produce nitrogen
monoxide and oxygen according to the following chemical equation.
2 NO2(g) → 2 NO(g) + O2(g).
A sample of NO 2(g) is initially placed in a 2.50-L reaction vessel at 300°C. If the half -life and
the rate constant at 300°C are 11 seconds and 0.54 M -1 s -1, respectively, how many moles of
NO 2 were in the original sample?
A) 15 mol
B) 5.9 mol
C) 0.42 mol
D) 0.17 mol 14) 15) Hydrogen iodide decomposes at 800 K via a second-order process to produce hydrogen and
iodine according to the following chemical equation.
2 HI(g) → H2(g) + I2(g)
At 800 K it takes 142 seconds for the initial concentration of HI to decrease from 6.75 × 10-2 M
to 3.50 × 10-2 M. What is the rate constant for the reaction at this temperature?
A) 10.3 M-1s-1
B) 9.69 × 10-2 M-1s-1
C) 5.12 × 10-4 M-1s-1
D) 1.95 × 103 M-1s-1 15) 16) The reaction: 2 HI → H2 + I2, is second order and the rate constant at 800 K is 9.70 × 10-2 M-1
s-1. How long will it take for 8.00 × 10-2 mol/L of HI to decrease to one-fourth of its initial
B) 124 s
C) 0.619 s
D) 429 s
A) 387 s 16) 3 Answer Key
Testname: UNTITLED1 1) C
16) A 4 ...
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