Chemistry (Chang), 10th Edition

Chapter 13: Chemical Kinetics

Self Assessment A

1
For the overall hypothetical reaction A + 5B ----> 4C the rate of appearance of C, given by Δ[C]/Δt, may also be expressed as:
A)<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0023654666/17481/ch13quizaq1a.gif','popWin', 'width=130,height=99,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (1.0K)</a>
B)<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0023654666/17481/ch13quizaq1b.gif','popWin', 'width=133,height=100,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (1.0K)</a>
C)<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0023654666/17481/ch13quizaq1c.gif','popWin', 'width=149,height=98,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (1.0K)</a>
D)<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0023654666/17481/ch13quizaq1d.gif','popWin', 'width=147,height=100,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (1.0K)</a>
2
A certain first order reaction, A ----> B, when performed at 25oC, is 46% complete after 68 min. What is the rate constant of this reaction?
A)9.1 x 10-3 min-1
B)1.14 x 10-2 min-1
C)31 min-1
D)-1.14 x 10-2 min-1
E)51 min-1
3
Determine the rate constant for a first order reaction that has a half-life of 26.7 min.
A)18.5 min-1
B)38.5 min-1
C)9.250 min-1
D)19.3 min-1
E)0.0260 min-1
4
A second order reaction has a rate constant of 1.0 x 10-3 M-1s-1. If the initial reactant concentration is 0.200 M, how long will it take for the concentration to become 0.0250 M?
A)4.0 x 104 s
B)3.5 x 104 min
C)3.5 x 104 s
D)8000 s
E)3.5 x 10-2 s
5
Determine the half-life of a second order reaction with k = 1.0 x 10-3 Lmol-1s-1 if the initial reactant concentration is 0.200 M.
A)200 s
B)5.0 x 103 s
C)0.005 s
D)2 x 10-4 s
E)None of the above
6
If the rate of the reaction PCl5 ----> PCl3 + Cl2 is increased by a factor of four when the PCl5 concentration doubles, the rate law for this reaction must be:
A)dependent on the PCl3 and Cl2 concentrations
B)first order with respect to PCl5
C)second order with respect to PCl5
D)fourth order with respect to PCl5
7
If a reaction has a rate constant of 3.7 x 10-3 s-1 at 25oC, and an activation energy of 43.6 kJ/mol, what will be the rate constant for this reaction at 75oC?
A)3.0 x 10-4
B)4.6 x 10-2
C)3.7 x 10-3
D)4.8 x 10-3
8
A catalyst increases the rate of a reaction by:
A)increasing the enthalpy of the reaction
B)lowering the activation energy of the reaction
C)increasing the activation energy of the reaction
D)decreasing the enthalpy of the reaction
9
The reaction H2(g) + I2(g) ----> 2 HI(g) is exothermic and has the following rate law at 298K: rate = k[H2][I2]. Addition of a catalyst would:
A)increase the rate of the forward reaction
B)increase the rate of both the forward and reverse reactions
C)increase the rate of the reverse reaction
D)cause no increase or decrease in the rate of the reaction
E)None of the above
10
Which of the following is a likely mechanism for the reaction CH3Cl + OH- ----> CH3OH + Cl-, which is first order with respect to each of the reactants?
A)A one-step mechanism involving a transition state that contains two hydroxide ions "attached" to the carbon atom of CH3Cl
B)A one-step mechanism involving a transition state that has a carbon partially bonded to both chlorine and oxygen
C)A two-step mechanism in which the chlorine leaves CH3Cl in a slow step, followed by rapid attack of the intermediate by the hydroxide ion
D)A two-step mechanism in which the chlorine leaves CH3Cl in a rapid step, followed by the slow attack of the intermediate by the hydroxide ion
11
Express the units for rate constants when the concentration is in moles per liter and time is in seconds for second-order reactions.
A)mol/L·s
B)s-1
C)Lmol-1s-1
D)None of the above
12
The reaction rate cannot be determined by any of the steps of a chemical reaction.
A)True
B)False
13
Determine the rate constant for the following first order reaction, 2A ----> B + C, if [A]0 = 0.050 M and after 120s the concentration of B increases to 0.015 M.
A)2.7x10-3s-1,
B)6x10-3s-1
C)7.6x10-3s-1
D)8.2x10-3s-1
14
Which of the following is incorrect concerning a catalyst?
A)Sets up a series elementary step.
B)The catalyst is partially consumed during the reaction.
C)Catalysts are not part of the product.
D)Heterogeneous catalysts are in a different phase than the reactants.
15
Biological enzymes are:
A)highly specific
B)DNA bases
C)decrease the rate of biological reactions
D)None of the above
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