The Foundations of Chemistry

704 CHAPTER 16: Chemical Kinetics

(c) Cl 234 Cl
Cl (fast, equilibrium)

Cl
H 2 S 34 HCl
HS (fast, equilibrium)

HS
Cl88nHCl
S (slow)

Cl 2 
H 2 S88nS
2HCl (overall)

*65.Write the overall reaction and the rate expressions that cor-

respond to the following reaction mechanisms. Be sure to

eliminate intermediates from the answers:

(a) A
B 34 C
D (fast, equilibrium)

(a) C
E88nF (slow)

(b) A 34 B
C (fast, equilibrium)

(a)C
D 34 E (fast, equilibrium)

(a) E88nF (slow)

*66.Write the overall reaction and the rate expressions that cor-

respond to the following mechanisms. Be sure to eliminate

intermediates from the answers:

(a) 2 A
B 34 D (fast, equilibrium)

(a) D
B88nE
F (slow)

(a) F88nG (fast)

(b) A
B 34 C (fast, equilibrium)

(a) C
D 34 F (fast, equilibrium)

(a) F88nG (slow)

*67.The ozone, O 3 , of the stratosphere can be decomposed by

reaction with nitrogen oxide (commonly called nitric

oxide), NO, from high-flying jet aircraft.

O 3 (g)
NO(g)88nNO 2 (g)
O 2 (g)

The rate expression is ratek[O 3 ][NO]. Which of the

following mechanisms are consistent with the observed rate

expression?

(a) NO
O 3 88nNO 3 
O (slow)

NO 3 
O88nNO 2 
O 2 (fast)

O 3 
NO88nNO 2 
O 2 (overall)

(b) NO
O 3 88nNO 2 
O 2 (slow)

(one step)

(c) O 3 88nO 2 
O (slow)

O
NO88nNO 2 (fast)

O 3 
NO88nNO 2 
O 2 (overall)

(d) NO88nN
O (slow)

O
O 3 88n2O 2 (fast)

O 2 
N88nNO 2 (fast)

O 3 
NO88nNO 2 
O 2 (overall)

(e) NO 34 N
O (fast, equilibrium)

O
O 3 88n2O 2 (slow)

O 2 
N88nNO 2 (fast)

O 3 
NO88nNO 2 
O 2 (overall)

*68.A proposed mechanism for the decomposition of ozone,

2O 3 n3O 2 , is

O 334 O 2 
O (fast, equilibrium)

O
O 3 88n2O 2 (slow)

Derive the rate equation for the net reaction.

*69.A mechanism for the gas-phase reaction

H 2 
I 2 88n2HI

was discussed in the chapter. (a) Show that this mechanism

predicts the correct rate law, ratek[H 2 ][I 2 ].

I 234 2I (fast, equilibrium)

I
H 234 H 2 I (fast, equilibrium)

H 2 I
I88n2HI (slow)

(b) Identify any reaction intermediates in this proposed

mechanism.

*70.The combination of Cl atoms is catalyzed by N 2 (g). The

following mechanism is suggested.

N 2 
Cl 34 N 2 Cl (fast, equilibrium)

N 2 Cl
Cl88nCl 2 
N 2 (slow)

(a) Identify any reaction intermediates in this proposed

mechanism. (b) Is this mechanism consistent with the

experimental rate law, ratek[N 2 ][Cl]^2?

*71.The reaction between NO and Br 2 was discussed in Sec-

tion 16-7. The following mechanism has also been

proposed.

2NO 34 N 2 O 2 (fast, equilibrium)

N 2 O 2 
Br 2 88n2NOBr (slow)

Is this mechanism consistent with the observation that the

reaction is second order in NO and first order in Br 2?

*72.The following mechanism for the reaction between H 2 and

CO to form formaldehyde, H 2 CO, has been proposed.

H 234 2H (fast, equilibrium)

H
CO88nHCO (slow)

H
HCO88nH 2 CO (fast)

(a) Write the balanced equation for the overall reaction.

(b) The observed rate dependence is found to be one-half

order in H 2 and first order in CO. Is this proposed reac-

tion mechanism consistent with the observed rate

dependence?

*73.The reaction between nitrogen dioxide and ozone,

2NO 2 
O 3 88nN 2 O 5 
O 2

has been studied at 231 K. The experimental rate equation

is ratek[NO 2 ][O 3 ]. (a) What is the order of the reac-

tion? (b) Is either of the following proposed mechanisms