Name___________________________________  Date __________________________  Period ___

Practice Quiz:  14.1, 14.2 = Factors that Affect Reaction Rates; Reaction Rates
 
MULTIPLE CHOICE.  Choose the one alternative that best completes the statement or answers the question. 

1) 

Consider the following reaction: 

	3A  →  2B 

The average rate of appearance of B is given by Δ[B]/Δt. Comparing the rate of appearance of B and the rate of disappearance of A, we get   

1) 

________
A) 

+2/3 
B) 

-2/3 
C) 

-3/2 
D) 

+1 
E) 

+3/2 

2) 

Which substance in the reaction below either appears or disappears the fastest? 

	4 NH3  +  7 O2  →  4 NO2  +  6 H2O

2) 

________
A) 

O2 
B) 

NH3
C) 

H2O 
D) 

NO2
E) 

The rates of appearance/disappearance are the same for all of these.  

A flask is charged with 0.124 mol of A and allowed to react to form B according to the reaction A(g) →B(g).  The following data are obtained for [A] as the reaction proceeds:

 
3) 

The average rate of disappearance of A between 10 s and 20 s is __________ mol/s. 

3) 

________
A) 

2.2 × 10-3 
B) 

4.4 × 10-3 
C) 

1.1 × 10-3 
D) 

9.90 × 10-3 
E) 

454 

4) 

The average rate of appearance of B between 20 s and 30 s is __________ mol/s. 

4) 

________
A) 

+1.5 × 10-3 
B) 

+7.3 × 10-3 
C) 

+5.0 × 10-4 
D) 

-7.3 × 10-3 
E) 

-1.5 × 10-3 

5) 

How many moles of B are present at 10 s? 

5) 

________
A) 

0.110 
B) 

0.014 
C) 

1.4 × 10-3  
D) 

0.011 
E) 

0.220 

The peroxydisulfate ion (S2O82 –) reacts with the iodide ion in aqueous solution via the reaction:

S2O82 – (aq)  +  3 I-  →  2 SO4 (aq) + I3- (aq)

An aqueous solution containing 0.050 M of S2O82 –ion and 0.072 M of I- is prepared, and the progress of the reaction followed by measuring [I-].  The data obtained is given in the table below.

 
6) 

The average rate of disappearance of I- between 400 s and 800 s is __________ M/s. 

6) 

________
A) 

2.6 × 10-4 
B) 

2.8 × 10-5 
C) 

5.8 × 10-5 
D) 

3.6 × 104 
E) 

1.4 × 10-5 

7) 

The average rate of disappearance of I between 1200 s and 1600 s is __________ M/s. 

7) 

________
A) 

1.2 × 10-5  
B) 

1.8 × 10-5  
C) 

2.0 × 10-5  
D) 

5.0 × 104  
E) 

1.6 × 10-4  

8) 

The concentration of S2O82- remaining at 800 s is __________ M. 

8) 

________
A) 

0.041 
B) 

0.076 
C) 

4.00 × 10-3 
D) 

0.015 
E) 

0.046 

9) 

At elevated temperatures, dinitrogen pentoxide decomposes to nitrogen dioxide and oxygen:

	2 N2O5(g)   →  4 NO2 (g)  +  O2 (g)

When the rate of formation of NO2 is 5.5 × 10-4 M/s, the rate of decomposition of N2O5 is __ M/s. 

9) 

________
A) 

5.5 × 10-4 
B) 

2.2 × 10-3 
C) 

2.8 × 10-4 
D) 

10.1 × 10-4 
E) 

1.4 × 10-4 

10) 

At elevated temperatures,  methylisonitrile (CH3NC) isomerizes to acetonitrile (CH3CN):

	CH3NC (g)  →  CH3CN (g)

At the start of the experiment, there are 0.200 mol of reactant (CH3NC) and 0 mol of product (CH3CN) in the reaction vessel.  After 25 min of reaction, 0.108 mol of reactant (CH3NC) remain.  The average rate of decomposition of methyl isonitrile, CH3NC, in this 25 min period is __________ mol/min. 

10) 

______
A) 

2.3 
B) 

0.092 
C) 

3.7 × 10-3  
D) 

0.54 
E) 

4.3 × 10-3  

11) 

A burning splint will burn more vigorously in pure oxygen than in air because 

11) 

______
A) 

nitrogen is a product of combustion and the system reaches equilibrium at a lower temperature. 
B) 

oxygen is a reactant in combustion and concentration of oxygen is higher in pure oxygen than is in air. 
C) 

oxygen is a catalyst for combustion. 
D) 

oxygen is a product of combustion. 
E) 

nitrogen is a reactant in combustion and its low concentration in pure oxygen catalyzes the combustion.  

12) 

Nitrogen dioxide decomposes to nitric oxide and oxygen via the reaction:

	2 NO2  →  2 NO  +  O2 

In a particular experiment at 300°C, [NO2] drops from 0.0100 to 0.00650 M in 100 s. The rate of disappearance of NO2 for this period is __________ M/s. 

12) 

______
A) 

0.35 
B) 

7.0 ×  
C) 

3.5 ×  
D) 

3.5 ×  
E) 

1.8 ×  

13) 

Of the units below, __________ are appropriate for a first-order reaction rate constant. 

13) 

______
A) 

L mol-1 s-1 
B) 

M s-1 
C) 

M-1 s-1 
D) 

s-1 
E) 

mol/L 

SHORT ANSWER.  Write the word or phrase that best completes each statement or answers the question. 

14) 

The relationship of absorbed light to the concentration of the substance absorbing the light is governed by __________. 

14) 

______________

TRUE/FALSE.  Write 'T' if the statement is true and 'F' if the statement is false. 

15) 

Rates of reaction can be positive or negative. 

15) 

______

16) 

The instantaneous rate of a reaction can be determined from the graph of molarity versus time at any point on the graph. 

16) 

______

MULTIPLE CHOICE.  Choose the one alternative that best completes the statement or answers the question. 

17) 

The rate of disappearance of HBr in the gas phase reaction

	2 HBr (g)  →  H2 (g) + Br2 (g)

is  0.301 M s – 1 at 150°C. The rate of appearance of Br2 is __________ M s-1 . 

17) 

______
A) 

0.0906 
B) 

1.66 
C) 

0.602 
D) 

0.549 
E) 

0.151 

18) 

The combustion of ethylene proceeds by the reaction

	C2H4 (g) + 3 O2 (g)  → 2 CO2  (g) +  2 H2O (g)

When the rate of disappearance of O2 is  0.28 M s-1, the rate of appearance of CO2 is ____ M s-1.

18) 

______
A) 

0.56 
B) 

0.42 
C) 

0.093 
D) 

0.84 
E) 

0.19 

 Practice Test 14.1 and  14.2 Answer Key

1) 

A 

2) 

A 

3) 

A 

4) 

A 

5) 

B 

6) 

B 

7) 

C 

8) 

A 

9) 

C 

10) 

C 

11) 

B 

12) 

D 

13) 

D 

14) 

Beer's Law 

15) 

FALSE 

16) 

FALSE 

17) 

E 

18) 

E