Chapter 12: Chemical Kinetics

	1.	The average rate of disappearance of ozone in the reaction  is found to be  atm over a certain interval of time. What is the rate of appearance of  during this interval?
A)	 atm/s	
B)	 atm/s	
C)	 atm/s	
D)	 atm/s	
E)	 atm/s	

ANS:	A	PTS:	1	DIF:	Easy	REF:	12.1
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate	
MSC:	Quantitative

	2.	The balanced equation for the reaction of bromate ion with bromide ion in acidic solution is given by:

At a particular instant in time, the value of  is  mol/L s. What is the value of  in the same units?
A)		
B)		
C)		
D)		
E)		

ANS:	A	PTS:	1	DIF:	Easy	REF:	12.1
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate	
MSC:	Quantitative

	3.	Consider the reaction 
What is the ratio of the initial rate of the appearance of water to the initial rate of disappearance of oxygen?
A)	1 : 1	
B)	2 : 1	
C)	1 : 2	
D)	2 : 2	
E)	3 : 2	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.1
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate	
MSC:	Conceptual

	4.	Consider the reaction: 
At a certain instant the initial rate of disappearance of the oxygen gas is X. What is the value of the appearance of water at the same instant?
A)	1.2 X	
B)	1.1 X	
C)	0.86 X	
D)	0.58 X	
E)	cannot be determined from the data	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.1
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate	
MSC:	Conceptual

	5.	For the reaction , at a particular instant in time, the rate of the reaction is 0.0223 M/s. What is the rate of change of A?
A)	–0.0223 M/s	
B)	0.112 M/s	
C)	–0.112 M/s	
D)	–0.00446 M/s	
E)	0.00446 M/s	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.1
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate	
MSC:	Conceptual

	6.	Consider the reaction X ® Y + Z
Which of the following is a possible rate law?
A)	Rate = k[X]	
B)	Rate = k[Y]	
C)	Rate = k[Y][Z]	
D)	Rate = k[X][Y]	
E)	Rate = k[Z]	

ANS:	A	PTS:	1	DIF:	Easy	REF:	12.2
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration	MSC:	Conceptual

	7.	Consider the following rate law: 
How are the exponents n and m determined?
A)	by using the balanced chemical equation	
B)	by using the subscripts for the chemical formulas	
C)	by using the coefficients of the chemical formulas	
D)	by educated guess	
E)	by experiment	

ANS:	E	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining the rate law	MSC:	Conceptual

	8.	The following data were obtained for the reaction of NO with O2. Concentrations are in molecules/cm3 and rates are in molecules/cm3×s.
[NO]0	[O2]0	Initial Rate	
1 ´ 1018	1 ´ 1018	2.0 ´ 1016	
2 ´ 1018	1 ´ 1018	8.0 ´ 1016	
3 ´ 1018	1 ´ 1018	18.0 ´ 1016	
1 ´ 1018	2 ´ 1018	4.0 ´ 1016	
1 ´ 1018	3 ´ 1018	6.0 ´ 1016	
What is the rate law?
A)	Rate = k[NO][O2]	
B)	Rate = k[NO][O2]2	
C)	Rate = k[NO]2[O2]	
D)	Rate = k[NO]2	
E)	Rate = k[NO]2[O2]2	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining the rate law	MSC:	Quantitative

	9.	The reaction of  with hydroxide ion proceeds with the formation of .

The following data were obtained at 55°C.
	[(CH3)3CBr]0	[OH–]0	Initial Rate	
Exp.	(mol/L)	(mol/L)	(mol/L)	
1	0.10	0.10	1.0 ´ 10–3	
2	0.20	0.10	2.0 ´ 10–3	
3	0.10	0.20	1.0 ´ 10–3	
4	0.30	0.20	?	
What will the initial rate (in mol/L·s) be in Experiment 4?
A)	3.0 ´ 10–3	
B)	6.0 ´ 10–3	
C)	9.0 ´ 10–3	
D)	18 ´ 10–3	
E)	none of these	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | experimental determination of rate			MSC:	Conceptual

	10.	For a reaction in which A and B react to form C, the following initial rate data were obtained:
[A]	[B]	Initial Rate of Formation of C	
(mol/L)	(mol/L)	(mol/L·s)	
0.10	0.10	1.00	
0.10	0.20	4.00	
0.20	0.20	8.00	
What is the rate law?
A)	Rate = k[A][B]	
B)	Rate = k[A]2[B]	
C)	Rate = k[A][B]2	
D)	Rate = k[A]2[B]2	
E)	Rate = k[A]3	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining the rate law	MSC:	Quantitative

	11.	Tabulated below are initial rate data for the reaction

Run					Initial
Rate (M/s)	
1	0.01	0.01	0.01	0.01	1 ´ 10–5	
2	0.01	0.02	0.01	0.01	2 ´ 10–5	
3	0.02	0.02	0.01	0.01	8 ´ 10–5	
4	0.02	0.02	0.02	0.01	8 ´ 10–5	
5	0.02	0.02	0.02	0.02	8 ´ 10–5	
The experimental rate law is:
A)	 	
B)		
C)		
D)		
E)		

ANS:	C	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining the rate law	MSC:	Quantitative

	12.	Tabulated below are initial rate data for the reaction:
               2Fe(CN)63– + 2I– ® 2Fe(CN)64– + I2
Run	[Fe(CN)63–]0	[I–]0	[Fe(CN)64–]0	[I2]0	Rate (M/s)	
1	0.01	0.01	0.01	0.01	1 ´ 10–5	
2	0.01	0.02	0.01	0.01	2 ´ 10–5	
3	0.02	0.02	0.01	0.01	8 ´ 10–5	
4	0.02	0.02	0.02	0.01	8 ´ 10–5	
5	0.02	0.02	0.02	0.02	8 ´ 10–5	
What is the value of k?
A)	107 M–5 s–1	
B)	103 M–3 s–1	
C)	10 M–2 s–1	
D)	50 M–2 s–1	
E)	none of these	

ANS:	C	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining the rate law	MSC:	Quantitative

A general reaction written as A + 2B ® C + 2D is studied and yields the following data:
	[A]0	[B]0	Initial D[C]/Dt	
	0.150 M	0.150 M	8.00 ´ 10–3 mol/L·s	
	0.150 M	0.300 M	1.60 ´ 10–2 mol/L·s	
	0.300 M	0.150 M	3.20 ´ 10–2 mol/L·s	

	13.	What is the order of the reaction with respect to B?
A)	0	
B)	1	
C)	2	
D)	3	
E)	4	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | reaction order		MSC:	Conceptual

	14.	What is the order of the reaction with respect to A?
A)	0	
B)	1	
C)	2	
D)	3	
E)	4	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | reaction order		MSC:	Conceptual

	15.	What is the overall order of the reaction?
A)	0	
B)	1	
C)	2	
D)	3	
E)	4	

ANS:	D	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | reaction order		MSC:	Conceptual

	16.	What is the numerical value of the rate constant?
A)	0.053	
B)	1.19	
C)	2.37	
D)	5.63	
E)	none of these (A-D)	

ANS:	C	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration	MSC:	Quantitative

	17.	Determine the initial rate of B consumption (D[B]/Dt) for the first trial?
A)	8.00 ´ 10–3 mol/L·s	
B)	1.60 ´ 10–2 mol/L·s	
C)	3.20 ´ 10–2 mol/L·s	
D)	4.00 ´ 10–3 mol/L·s	
E)	none of these (A-D)	

ANS:	B	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | change of concentration with time		MSC:	Conceptual

	18.	Determine the initial rate of C production (D[C]/Dt) if [A] = 0.200 M and [B] = 0.500 M.
A)	4.74 ´ 10–2 mol/L·s	
B)	2.37 ´ 10–1 mol/L·s	
C)	1.19 ´ 10–1 mol/L·s	
D)	8.23 ´ 10–2 mol/L·s	
E)	none of these (A-D)	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration	MSC:	Quantitative

Consider the following data concerning the equation:
     H2O2 + 3I– + 2H+ ® I3– + 2H2O
 	[H2O2]		[I–]	[H+]	rate	
 I	0.100 M		5.00 ´ 10–4 M	1.00 ´ 10–2 M	0.137 M/sec	
 II.	0.100 M		1.00 ´ 10–3 M	1.00 ´ 10–2 M	0.268 M/sec	
 III.	0.200 M		1.00 ´ 10–3 M	1.00 ´ 10–2 M	0.542 M/sec	
 IV.	0.400 M		1.00 ´ 10–3 M	2.00 ´ 10–2 M	1.084 M/sec	

	19.	The rate law for this reaction is
A)	rate = k[H2O2][I–][H+]	
B)	rate = k[H2O2]2[I–]2[H+]2	
C)	rate = k[I–][H+]	
D)	rate = k[H2O2][H+]	
E)	rate = k[H2O2][I–]	

ANS:	E	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining the rate law	MSC:	Conceptual

	20.	The average value for the rate constant k (without units) is
A)	2710	
B)	2.74 ´ 104	
C)	137	
D)	108	
E)	none of these	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration	MSC:	Quantitative

	21.	Two mechanisms are proposed:
I.		
II.		
Which mechanism and which step as the rate determining step would best fit the data?

A)	Mechanism I, with the first step the rate determining step.	
B)	Mechanism I, with the second step the rate determining step.	
C)	Mechanism II, with the first step rate determining.	
D)	Mechanism II, with the second step rate determining.	
E)	None of the above could be correct.	

ANS:	A	PTS:	1	DIF:	Easy	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism | rate determining step	MSC:	Conceptual

The following initial rate data were found for the reaction
	2MnO4– + 5H2C2O4 + 6H+ ® 2Mn2+ + 10CO2 + 8H2O	
	[MnO4–]0		[H2C2O4]0	[H+]0	Initial Rate (M/s)	
	1 ´ 10–3		1 ´ 10–3	1.0	2 ´ 10–4	
	2 ´ 10–3		1 ´ 10–3	1.0	8 ´ 10–4	
	2 ´ 10–3		2 ´ 10–3	1.0	1.6 ´ 10–3	
	2 ´ 10–3		2 ´ 10–3	2.0	1.6 ´ 10–3	

	22.	Which of the following is the correct rate law?
A)	Rate = k[MnO4–]2[H2C2O4]5[H+]6	
B)	Rate = k[MnO4–]2[H2C2O4][H+]	
C)	Rate = k[MnO4–][H2C2O4][H+]	
D)	Rate = k[MnO4–]2[H2C2O4]	
E)	Rate = k[MnO4–]2[H2C2O4]2	

ANS:	D	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining the rate law	MSC:	Conceptual

	23.	What is the value of the rate constant?
A)	2 ´ 105 M×s–1	
B)	2 ´ 105 M–2×s–1	
C)	200 M–1×s–1	
D)	200 M–2×s–1	
E)	2 ´ 10–4 M×s–1	

ANS:	B	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration	MSC:	Quantitative

The following questions refer to the reaction between nitric oxide and hydrogen
          2NO + H2 ® N2O + H2O
Experiment	Initial [NO], M	Initial [H2], M	Initial Rate of Disappearance of NO (mol/L sec)	
1	6.4 ´ 10–3	2.2 ´ 10–3	2.7 ´ 10–5	
2	12.8 ´ 10–3	2.2 ´ 10–3	1.1 ´ 10–4	
3	6.4 ´ 10–3	4.5 ´ 10–3	5.4 ´ 10–5	

	24.	What is the rate law for this reaction?
A)	Rate = k[NO]	
B)	Rate = k[NO]2	
C)	Rate = k[NO]2[H2]	
D)	Rate = k[NO][H2]	
E)	Rate = k[N2O][H2O]	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining the rate law	MSC:	Conceptual

	25.	What is the magnitude of the rate constant for this reaction?
A)	0.66	
B)	4.2 ´ 10–3	
C)	870	
D)	1.9	
E)	300	

ANS:	E	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration	MSC:	Quantitative

	26.	What are the units for the rate constant for this reaction?
A)	L/mol·s	
B)	L2/mol2·s	
C)	mol/L·s	
D)	s–2	
E)	L–2	

ANS:	B	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration	MSC:	Conceptual

	27.	What is the order of this reaction?
A)	3	
B)	2	
C)	1	
D)	0	
E)	cannot be determined from the data	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | reaction order		MSC:	Conceptual

The reaction H2SeO3(aq) 6I–(aq) + 4H+(aq) ® 2I3–(aq) + 3H2O(l) + Se(s) was studied at 0°C by the method of initial rates:

[H2SeO3]0	[H+]0	[I–]0	Rate (mol/L s)	
1.0 ´ 10–4	2.0 ´ 10–2	2.0 ´ 10–2	1.66 ´ 10–7	
2.0 ´ 10–4	2.0 ´ 10–2	2.0 ´ 10–2	3.33 ´ 10–7	
3.0 ´ 10–4	2.0 ´ 10–2	2.0 ´ 10–2	4.99 ´ 10–7	
1.0 ´ 10–4	4.0 ´ 10–2	2.0 ´ 10–2	6.66 ´ 10–7	
1.0 ´ 10–4	1.0 ´ 10–2	2.0 ´ 10–2	0.41 ´ 10–7	
1.0 ´ 10–4	2.0 ´ 10–2	4.0 ´ 10–2	13.4 ´ 10–7	
1.0 ´ 10–4	4.0 ´ 10–2	4.0 ´ 10–2	5.33 ´ 10–6	

	28.	The rate law is
A)	Rate = k[H2SeO3][H+][I–]	
B)	Rate = k[H2SeO3][H+]2[I–]	
C)	Rate = k[H2SeO3][H+][I–]2	
D)	Rate = k[H2SeO3]2[H+][I–]	
E)	Rate = k[H2SeO3][H+]2[I–]3	

ANS:	E	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining the rate law	MSC:	Conceptual

	29.	The numerical value of the rate constant is
A)	5.2 ´ 105	
B)	2.1 ´ 102	
C)	4.2	
D)	1.9 ´ 10–6	
E)	none of these	

ANS:	A	PTS:	1	DIF:	Difficult	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration	MSC:	Quantitative

The following questions refer to the reaction shown below:
	
			Initial Rate of	
	Initial [A]	Initial [B]	Disappearance of A	
Experiment	(mol/L)	(mol/L)	(mol/L·s)	
1	0.16	0.15	0.08	
2	0.16	0.30	0.30	
3	0.08	0.30	0.08	

	30.	What is the rate law for this reaction?
A)	Rate = k[A][B]	
B)	Rate = k[A]2[B]	
C)	Rate = k[A][B]2	
D)	Rate = k[A]2[B]2	
E)	Rate = k[B]	

ANS:	D	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining the rate law	MSC:	Conceptual

	31.	What is the magnitude of the rate constant for the reaction?
A)	140	
B)	79	
C)	119	
D)	164	
E)	21	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration	MSC:	Quantitative

	32.	What are the units for the rate constant for this reaction?
A)	L/mol·s	
B)	L2/mol2·s	
C)	mol/L·s	
D)	L3/mol3·s	
E)	mol3/L	

ANS:	D	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration	MSC:	Conceptual

	33.	What is the order of this reaction?
A)	4	
B)	3	
C)	2	
D)	1	
E)	0	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | reaction order		MSC:	Conceptual

	34.	Initial rate data have been determined at a certain temperature for the gaseous reaction
2NO + 2H2 ® N2 + 2H2O
[NO]0	[H2]0	Initial Rate (M/s)	
0.10	0.20	0.0150	
0.10	0.30	0.0225	
0.20	0.20	0.0600	
What is the value of the rate constant?
A)	7.5	
B)	3.0 ´ 10–3	
C)	380	
D)	0.75	
E)	3.0 ´ 10–4	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration	MSC:	Quantitative

	35.	The following data were obtained at 25°C:
[A]0	[B]0	[C]0	Rate	
0.1	0.2	0.3	0.063	
0.3	0.4	0.2	0.084	
0.6	0.4	0.2	0.168	
0.3	0.4	0.1	0.021	
0.6	0.2	0.2	0.168	
What is the correct rate law?
A)	Rate = k[A][B][C]	
B)	Rate = k[A][B][C]2	
C)	Rate = k[A][C]	
D)	Rate = k[A]3[B]2[C]	
E)	Rate = k[A][C]2	

ANS:	E	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining the rate law	MSC:	Conceptual

The oxidation of Cr3+ to CrO42– can be accomplished using Ce4+ in a buffered solution. The following data were obtained:
	Relative
Initial Rate	[Ce4+]0	[Ce3+]0	[Cr3+]0	
	1	2.0 ´ 10–3	1.0 ´ 10–2	3.0 ´ 10–2	
	2	4.0 ´ 10–3	2.0 ´ 10–2	3.0 ´ 10–2	
	4	4.0 ´ 10–3	1.0 ´ 10–2	3.0 ´ 10–2	
	16	8.0 ´ 10–3	2.0 ´ 10–2	6.0 ´ 10–2	

	36.	Determine the order in the rate law of the species Ce4+.
A)	1	
B)	2	
C)	3	
D)	–1	
E)	–2	

ANS:	B	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | reaction order		MSC:	Conceptual

	37.	Determine the order in the rate law of the species Ce3+.
A)	1	
B)	2	
C)	3	
D)	–1	
E)	–2	

ANS:	D	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | reaction order		MSC:	Conceptual

	38.	Determine the order in the rate law of the species Cr3+.
A)	1	
B)	2	
C)	3	
D)	–1	
E)	–2	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | reaction order		MSC:	Conceptual

	39.	The rate expression for a particular reaction is rate = k[A][B]2. If the initial concentration of B is increased from 0.1 M to 0.3 M, the initial rate will increase by which of the following factors?
A)	2	
B)	6	
C)	12	
D)	3	
E)	9	

ANS:	E	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | reaction order		MSC:	Conceptual

	40.	The following data were obtained for the reaction 2A + B ® C where rate = D[C]/Dt
[A](M)	[B](M)	Initial Rate (M/s)	
0.100		0.0500	2.13 ´ 10–4	
0.200		0.0500	1.70 ´ 10–2	
0.400		0.100	1.36 ´ 10–1	
What is the value of the rate constant?
A)	2.13	
B)	0.213	
C)	0.426	
D)	1.70	
E)	none of these	

ANS:	B	PTS:	1	DIF:	Moderate	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws
MSC:	Quantitative

	41.	The reaction 2A + 5B ® products is second order in A and first order in B. What is the rate law for this reaction?
A)	rate = k[A]2[B]5	
B)	rate = k[A]1[B]2	
C)	rate = k[A]2[B]1	
D)	rate = k[A]5[B]2	
E)	rate = k[A]2/7[B]5/7	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | reaction order		MSC:	Conceptual

	42.	The reaction 3A + 4B ® products is second order in A and second order in B. What is the overall order of the reaction?
A)	0	
B)	7	
C)	2	
D)	4	
E)	6	

ANS:	D	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | reaction order		MSC:	Conceptual

	43.	The reactants A and B are mixed, and the reaction is timed until a color change occurs. The data are as follows:
[A]	[B]	Time (s)	
0.100	0.140	25	
0.050	0.140	50	
0.100	0.070	100	
The order of the reaction in terms of B is
A)	2.	
B)	.	
C)	0.	
D)	.	
E)	1.	

ANS:	A	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining the rate law	MSC:	Quantitative

	44.	The reaction  has the following rate law:

After a period of  s, the concentration of NO falls from an initial value of 2.8 ´ 10–3 mol/L to 2.0 ´ 10–3 mol/L. What is the rate constant, k?
A)	 	
B)	 	
C)	 	
D)	 	
E)	 	

ANS:	E	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | second-order reaction			MSC:	Quantitative

	45.	The following data were collected for the decay of HO2 radicals:
Time	[HO2]	Time	[HO2]	
0 s	1.0 ´ 1011 molec/cm3	14 s	1.25 ´ 1010 molec/cm3	
2 s	5.0 ´ 1010 molec/cm3	30 s	6.225 ´ 109 molec/cm3	
6 s	2.5 ´ 1010 molec/cm3	
Which of the following best describes the reaction?
A)	The decay of HO2 occurs by a first-order process.	
B)	The half-life of the reaction is 2 ms.	
C)	A plot of ln [HO2] versus time is linear with a slope of –k.	
D)	The rate of the reaction increases with time.	
E)	A plot of 1/[HO2] versus time gives a straight line.	

ANS:	E	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data		MSC:	Conceptual

	46.	A first-order reaction is 45% complete at the end of 43 minutes. What is the length of the half-life of this reaction?
A)	50. min	
B)	37 min	
C)	2.7 h	
D)	62 min	
E)	none of these	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

The following questions refer to the gas-phase decomposition of ethylene chloride.
         C2H5Cl ® products
Experiment shows that the decomposition is first order.
The following data show kinetics information for this reaction:
  Time (s)	    ln [C2H5Cl] (M)	
    1.0	            –1.625	
    2.0	            –1.735	

	47.	What is the rate constant for this decomposition?
A)	0.29/s	
B)	0.35/s	
C)	0.11/s	
D)	0.02/s	
E)	0.22/s	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

	48.	What was the initial concentration of the ethylene chloride?
A)	0.29 M	
B)	0.35 M	
C)	0.11 M	
D)	0.02 M	
E)	0.22 M	

ANS:	E	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

	49.	What would the concentration be after 5.0 seconds?
A)	0.13 M	
B)	0.08 M	
C)	0.02 M	
D)	0.19 M	
E)	0.12 M	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

	50.	What is the half-life time for this reaction?
A)	0.7 s	
B)	1.3 s	
C)	8.9 s	
D)	6.3 s	
E)	2.2 s	

ANS:	D	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Quantitative

	51.	For a reaction: , [A]0 = 4.2 M, and the first two half-lives are 56 and 28 minutes, respectively. Calculate k (without units).
A)		
B)		
C)		
D)		
E)	none of these	

ANS:	C	PTS:	1	DIF:	Difficult	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Quantitative

	52.	For a reaction: , [A]0 = 6.0 M, and the first two half-lives are 56 and 28 minutes, respectively. Calculate [A] at t = 105.9 minutes.
A)	5.7 M	
B)	12 M	
C)	0.68 M	
D)	0.33 M	
E)	none of these	

ANS:	D	PTS:	1	DIF:	Difficult	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | zero-order reaction	MSC:	Quantitative

	53.	For which order reaction is the half-life of the reaction proportional to 1/k (k is the rate constant)?
A)	zero order	
B)	first order	
C)	second order	
D)	all of the above	
E)	none of the above	

ANS:	D	PTS:	1	DIF:	Easy	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Conceptual

The kinetics of the reaction  were studied and the following results obtained, where the rate law is:

For a run where [A]0 = 1.0 ´ 10–3 M and [B]0 = 5.0 M, a plot of ln [A] versus t was found to give a straight line with slope = –5.0 ´ 10–2 s–1.
For a run where [A]0 = 1.0 ´ 10–3 M and [B]0 = 10.0 M, a plot of ln [A] versus t was found to give a straight line with slope = –7.1 ´ 10–2 s–1.

	54.	What is the value of n?
A)	0	
B)	0.5	
C)	1	
D)	1.5	
E)	2	

ANS:	C	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data		MSC:	Conceptual

	55.	What is the value of m?
A)	0	
B)	0.5	
C)	1	
D)	1.5	
E)	2	

ANS:	B	PTS:	1	DIF:	Difficult	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data		MSC:	Conceptual

	56.	Calculate the value of k (ignore units).
A)	22	
B)	10	
C)	50	
D)	1.1	
E)	none of these	

ANS:	A	PTS:	1	DIF:	Difficult	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data		MSC:	Quantitative

For the reaction , the following data were collected:
	t (minutes)	[N2O5] (mol/L)	
	0	1.24 ´ 10–2	
	10.	0.92 ´ 10–2	
	20.	0.68 ´ 10–2	
	30.	0.50 ´ 10–2	
	40.	0.37 ´ 10–2	
	50.	0.28 ´ 10–2	
	70.	0.15 ´ 10–2	

	57.	The order of this reaction in N2O5 is
A)	0	
B)	1	
C)	2	
D)	3	
E)	none of these	

ANS:	B	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data		MSC:	Conceptual

	58.	The concentration of O2 at t = 10. minutes is
A)	2.0 ´ 10–4 mol/L	
B)	0.32 ´ 10–2 mol/L	
C)	0.16 ´ 10–2 mol/L	
D)	0.64 ´ 10–2 mol/L	
E)	none of these	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data		MSC:	Quantitative

	59.	The initial rate of production of NO2 for this reaction is approximately
A)	7.4 ´ 10–4 mol/L·min	
B)	3.2 ´ 10–4 mol/L·min	
C)	1.24 ´ 10–2 mol/L·min	
D)	1.6 ´ 10–4 mol/L·min	
E)	none of these	

ANS:	A	PTS:	1	DIF:	Difficult	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data		MSC:	Quantitative

	60.	The half-life of this reaction is approximately
A)	15 minutes	
B)	18 minutes	
C)	23 minutes	
D)	36 minutes	
E)	45 minutes	

ANS:	C	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Quantitative

	61.	The concentration N2O5 at 100 minutes will be approximately
A)	0.03 ´ 10–2 mol/L	
B)	0.06 ´ 10–2 mol/L	
C)	0.10 ´ 10–2 mol/L	
D)	0.01 ´ 10–2 mol/L	
E)	none of these	

ANS:	B	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data		MSC:	Quantitative

The following questions refer to the hypothetical reaction A + B ® products. The kinetics data given can be analyzed to answer the questions.
	[A]0	[B]0	Rate of decrease	
	(mol/L)	(mol/L)	of [A] (M/s)	
	5.0	5.0	X	
	10.0	5.0	2X	
	5.0	10.0	2X	
	Time (s)	[B] (mol/L)	
	10.0	100	
	20.0	100	
	30.0	100	

	62.	The rate law for the reaction is Rate = k[A]x[B]y. What are the values of x and y?
A)	x = 0     y = 1	
B)	x = 1     y = 0	
C)	x = 1     y = 1	
D)	x = 2     y = 1	
E)	x = 1     y = 2	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining the rate law	MSC:	Conceptual

	63.	What form will the pseudo-rate law have?
A)	Rate = k'[A]x	
B)	Rate = k'[B]y	
C)	Rate = k'[A]x[B]y	
D)	Rate = kk'[A]x	
E)	Rate = kk'[B]y	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining the rate law	MSC:	Conceptual

	64.	Determine the magnitude of the pseudo-rate constant (k') if the magnitude of X in the rate data is 0.00905.
A)	4.3 ´ 10–3	
B)	1.2 ´ 10–2	
C)	0.86	
D)	0.31	
E)	1.81 ´ 10–3	

ANS:	E	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration	MSC:	Quantitative

The reaction A ® B + C is known to be zero order in A with a rate constant of 5.0 ´ 10–2 mol/L·s at 25°C. An experiment was run at 25°C where [A]0 = 1.0 ´ 10–3 M.

	65.	The integrated rate law is
A)	[A] = kt	
B)	[A] – [A]0 = kt	
C)		
D)		
E)	[A]0 – [A] = kt	

ANS:	E	PTS:	1	DIF:	Easy	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | zero-order reaction	MSC:	Conceptual

	66.	What is the concentration of B after 5 ´ 10–3 sec?
A)	5.0 ´ 10–5 M	
B)	5.0 ´ 10–4 M	
C)	7.5 ´ 10–4 M	
D)	2.5 ´ 10–4 M	
E)	none of these	

ANS:	D	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | zero-order reaction	MSC:	Quantitative

	67.	The reaction  is known to be zero order in A with a rate constant of 5.0 ´ 10–2 mol/L s at 25°C. An experiment was run at 25°C where [A]0 = 2.0 ´ 10–3 M. After 5.0 minutes, the rate is
A)	5.0 ´ 10–2 mol/L·s	
B)	2.5 ´ 10–2 mol/L·s	
C)	1.3 ´ 10–2 mol/L·s	
D)	2.0 ´ 10–3 mol/L·s	
E)	none of these	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | zero-order reaction	MSC:	Quantitative

	68.	The reaction  is known to be zero order in A with a rate constant of 5.0 ´ 10–2 mol/L s at 25°C. An experiment was run at 25°C where [A]0 =  M. The half-life for the reaction is
A)	 s	
B)	 s	
C)	 s	
D)	 s	
E)	none of these	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Quantitative

	69.	The reaction

exhibits the rate law

where k = 1.0 ´ 10–5 M–1 s–1 at 25°C. This reaction is run where the initial concentration of NOBr ([NOBr]0) is 0.11 M. What is one half-life for this experiment?
A)	 s	
B)	 s	
C)	 s	
D)	 s	
E)	none of these	

ANS:	D	PTS:	1	DIF:	Easy	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | integrated rate laws | half-life of a reaction		MSC:	Quantitative

	70.	The reaction

exhibits the rate law

where k = 1.0 ´ 10–5 M–1 × s–1 at 25°C. This reaction is run where the initial concentration of NOBr ([NOBr]0) is 1.00 ´ 10–1 M.
The [NO] after 1.00 hour has passed is
A)	3.6 ´ 10–4 M	
B)	9.9 ´ 10–3 M	
C)	9.7 ´ 10–3 M	
D)	1.0 ´ 10–3 M	
E)	none of these	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | second-order reaction			MSC:	Quantitative

For the reaction A ® Products, successive half-lives are observed to be 10.0 min and 40.0 min.

	71.	The reaction follows the integrated rate law
A)		
B)		
C)		
D)		
E)	none of these	

ANS:	C	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Conceptual

	72.	At the beginning of the reaction, [A] was 0.71 M. The numerical value of the rate constant is
A)	0.069	
B)	0.14	
C)	10.	
D)	0.036	
E)	none of these	

ANS:	B	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Quantitative

	73.	The reaction

is first order in N2O5. For this reaction at 45oC, the rate constant k = 1.0 ´ 10–5 s–1, where the rate law is defined as

For a particular experiment ([N2O5]0 = 1.0 ´ 10–3 M), calculate [N2O5] after 3.5 ´ 105 seconds.
A)	3.5 M	
B)	1.0 ´ 10–3 M	
C)	3.0 ´ 10–5 M	
D)	0 M	
E)	10 M	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

Consider the reaction 3A + B + C ® D + E where the rate law is defined as 
.
An experiment is carried out where [B]0 = [C]0 = 1.00 M and [A]0 = 1.00 ´ 10–4 M.

	74.	After 3.00 minutes, [A] = 3.26 ´ 10–5 M. The value of k is
A)	6.23 ´ 10–3 L3/mol3·s	
B)	3.26 ´ 10–5 L3/mol3·s	
C)	1.15 ´ 102 L3/mol3·s	
D)	1.00 ´ 108 L3/mol3·s	
E)	none of these	

ANS:	C	PTS:	1	DIF:	Difficult	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws
MSC:	Quantitative

	75.	The half-life for this experiment is
A)	1.11 ´ 102 s	
B)	87.0 s	
C)	6.03 ´ 10–3 s	
D)	117 s	
E)	none of these	

ANS:	B	PTS:	1	DIF:	Difficult	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Quantitative

	76.	The concentration of C after 10.0 minutes is
A)	1.00 M	
B)	1.10 ´ 10–5 M	
C)	0.330 M	
D)	0.100 M	
E)	none of these	

ANS:	A	PTS:	1	DIF:	Easy	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | experimental determination of rate			MSC:	Conceptual

	77.	The concentration of A after 10.0 minutes is
A)	1.06 ´ 10–9 M	
B)	2.38 ´ 10–6 M	
C)	9.80 ´ 10–6 M	
D)	1.27 ´ 10–5 M	
E)	none of these	

ANS:	D	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws
MSC:	Quantitative

	78.	The reaction

is second order in A. When [A]0 = 0.100 M, the reaction is 20.0% complete in 35.9 minutes. Calculate the value of the rate constant (in L/min·mol).
A)	6.96 ´ 10–2	
B)	5.57 ´ 10–4	
C)	1.57	
D)	1.11	
E)	none of these	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | second-order reaction			MSC:	Quantitative

	79.	The reaction

is second order in A. When [A]0 = 0.100 M, the reaction is 20.0% complete in 43.2 minutes. Calculate the half-life for the reaction.
A)	1.73 ´ 102 min	
B)	10.8 min	
C)	2.16 ´ 104 min	
D)	7.68 min	
E)	none of these	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Quantitative

	80.	A first-order reaction is 40.0% complete at the end of 48.1 minutes. What is the value of the rate constant (in min–1)?
A)	1.90 ´ 10–2	
B)	1.06 ´ 10–2	
C)	94.2	
D)	52.5	
E)	none of these	

ANS:	B	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

	81.	The OH· radical disproportionates according to the elementary chemical reaction  This reaction is second order in OH·. The rate constant for the reaction is 2.0 ´ 10–12 cm3/molecules at room temperature. If the initial OH concentration is 1.3 ´ 1013 molecules/cm3, what is the first half-life for the reaction?
A)	3.5 ´ 1011 s	
B)	2.6 ´ 101 s	
C)	3.8 ´ 10–2 s	
D)	7.7 ´ 10–14 s	
E)	1.9 ´ 10–2 s	

ANS:	C	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Quantitative

	82.	At a particular temperature, N2O5 decomposes according to a first-order rate law with a half-life of 3.0 s. If the initial concentration of N2O5 is 1.0 ´ 1016 molecules/cm3, what will be the concentration in molecules/cm3 after 16.1 s?
A)	2.4 ´ 1014	
B)	3.3 ´ 101	
C)	1.0 ´ 1016	
D)	1.4 ´ 1014	
E)	2.3 ´ 10–1	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

	83.	At a given temperature, a first-order reaction has a rate constant of 3.4 ´ 10–3 s–1. The time required for the reaction to be 44% completed is
A)	4.0 min	
B)	1.2 min	
C)	20 min	
D)	2.8 min	
E)	19 min	

ANS:	D	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

	84.	A chemical reaction that is first order in X is observed to have a rate constant of 1.7 ´ 10–2s–1. If the initial concentration of X is 1.0 M, what is the concentration of X after 190 s?
A)	25 M	
B)	0.68 M	
C)	0.24 M	
D)	0.96 M	
E)	0.040 M	

ANS:	E	PTS:	1	DIF:	Easy	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

	85.	A particular first-order reaction has a rate constant of 0.0107 s–1. What is the half-life for this reaction?
A)	1.00 s	
B)	64.6 s	
C)	93.2 s	
D)	0.0155 s	
E)	0.0107 s	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Quantitative

	86.	The reaction A ® products is first order. If the initial concentration of A is 0.528 M and, after 16.3 seconds have elapsed, the concentration of A has fallen to 0.0122 M, what is the rate constant of the reaction?
A)	0.231 s–1	
B)	0.0425 s–1	
C)	0.0316 s–1	
D)	4.91 s–1	
E)	0.0613 s–1	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

	87.	The reaction A ® products is second order. If the initial concentration of A is 0.436 M and, after 52.8 seconds have elapsed, the concentration of A has fallen to 0.0476 M, what is the rate constant of the reaction?
A)	0.0419 M–1 s–1	
B)	0.354 M–1 s–1	
C)	0.0131 M–1 s–1	
D)	0.00736 M–1 s–1	
E)	0.0189 M–1 s–1	

ANS:	B	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | second-order reaction			MSC:	Quantitative

	88.	The radioactive nuclide  undergoes first-order decay with a half-life of 9.31 min. If a quantity of  is produced, what fraction remains after 82.5 seconds?
A)	0.113	
B)	0.00215	
C)	0.148	
D)	0.903	
E)	0.0973	

ANS:	D	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

	89.	63Ni decays by a first-order process via the emission of a beta particle. The 63Ni isotope has a half-life of 100. years. How long will it take for 67% of the nickel to undergo decay?
A)	58 years	
B)	0.77 years	
C)	69 years	
D)	25 years	
E)	160 years	

ANS:	E	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

Two isomers (A and B) of a given compound dimerize as follows:
     
Both processes are known to be second order in reactant, and k1 is known to be 0.25 L/mol·s at 25°C, where
     
In a particular experiment, A and B were placed in separate containers at 25°, where [A]0 = 1.0 ´ 10–2 M and [B]0 = 2.5 ´ 10–2 M. It was found that [A] = 3[B] after the reactions progressed for 3.0 minutes.

	90.	Calculate the concentration of A2 after 3.0 minutes.
A)	2.8 ´ 10–22 M	
B)	6.9 ´ 10–3 M	
C)	3.1 ´ 10–3 M	
D)	1.6 ´ 10–3 M	
E)	none of these	

ANS:	D	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | second-order reaction			MSC:	Quantitative

	91.	Calculate the value of  where
     
A)	2.2 L/mol·s	
B)	0.75 L/mol·s	
C)	1.9 L/mol·s	
D)	0.21 L/mol·s	
E)	none of these	

ANS:	A	PTS:	1	DIF:	Difficult	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | second-order reaction			MSC:	Quantitative

	92.	Two isomers (A and B) of a given compound dimerize as follows:

Both processes are known to be second order in reactant, and k1 is known to be 0.24 L/mol s at 25°C, where:

In a particular experiment, A and B were placed in separate containers at 25oC, where [A]0 = 1.0 ´ 10–2 M and [B]0 = 2.5 ´ 10–2 M. It was found that [A] = 3[B] after the reactions progressed for 3.0 minutes. Calculate the half-life for the reaction involving A.
A)	 s	
B)	 s	
C)	 s	
D)	 s	
E)	none of these	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Quantitative

	93.	The decomposition of N2O5(g) to NO2(g) and O2(g) obeys first-order kinetics. Assuming the form of the rate law is:

where k = 3.4 ´ 10–5 s–1 at 25°C, what is the initial rate of reaction at 25°C where [N2O5]0 = 8.2 ´ 10–2 M?
A)	 mol/L·s	
B)	 mol/L·s	
C)	 mol/L·s	
D)	 mol/L·s	
E)	none of these	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

	94.	The decomposition of N2O5(g) to NO2(g) and O2(g) obeys first-order kinetics. Assuming the form of the rate law is:

where k = 5.4 ´ 10–5 s–1 at 25°C, what is the half-life for the reaction described?
A)	 s	
B)	 s	
C)	 s	
D)	 s	
E)	none of these	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Quantitative

	95.	Consider a reaction of the type aA ® Products in which the rate law is found to be rate = k[A]3 (yes, a termolecular reaction is improbable but possible). If the first half-life of the reaction is found to be 40 seconds, what is the time for the second half-life?
A)	10 seconds	
B)	20 seconds	
C)	80 seconds	
D)	160 seconds	
E)	320 seconds	

ANS:	D	PTS:	1	DIF:	Difficult	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Quantitative

	96.	The reaction  obeys the rate law:
at 500. K.
If the initial concentration of NO2 is 1.00 M, how long will it take for the [NO2] to decrease to 35.8% of its initial value?
A)	45.9 s	
B)	73 s	
C)	128 s	
D)	 s	
E)	cannot be determined from this data	

ANS:	C	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | second-order reaction			MSC:	Quantitative

	97.	If the reaction 2HI ® H2 + I2 is second order, which of the following will yield a linear plot?
A)	log [HI] vs time	
B)	1/[HI] vs time	
C)	[HI] vs time	
D)	ln [HI] vs time	
E)	None of these.	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data		MSC:	Conceptual

	98.	The reaction 3NO ® N2O + NO2 is found to obey the rate law, Rate = k[NO]2. If the first half-life of the reaction is found to be 2.0 s, what is the length of the fourth half-life?
A)	2.0 s	
B)	4.0 s	
C)	8.0 s	
D)	12.0 s	
E)	16.0 s	

ANS:	E	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Conceptual

	99.	In 6 M HCl, the complex ion Ru(NH3)63+ decomposes to a variety of products. The reaction is first order in Ru(NH3)63+ and has a half-life of 14 hours at 25°C. Under these conditions, how long will it take for the [Ru(NH3)63+] to decrease to 23.5% of its initial value?
A)	5.4 hours	
B)	9.7 hours	
C)	3.3 hours	
D)	14 hours	
E)	29 hours	

ANS:	E	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

	100.	The elementary chemical reaction O + ClO ® Cl + O2 is made pseudo-first order in oxygen atoms by using a large excess of ClO radicals. The rate constant for the reaction is 2.7 cm3/molecule×s. If the initial concentration of ClO is 1.0 ´ 1011 molecules/cm3, how long will it take for the oxygen atoms to decrease to 10.% of their initial concentration?
A)	1.2 s	
B)	0.039 s	
C)	0.26 s	
D)	0.85 s	
E)	2.6 s	

ANS:	D	PTS:	1	DIF:	Moderate	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

	101.	Determine the molecularity of the following elementary reaction: O3 ® O2 + O.
A)	unimolecular	
B)	bimolecular	
C)	termolecular	
D)	quadmolecular	
E)	molecularity cannot be determined	

ANS:	A	PTS:	1	DIF:	Easy	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | elementary reaction | molecularity		MSC:	Conceptual

	102.	The decomposition of ozone may occur through the two-step mechanism shown:

The oxygen atom is considered to be a(n)
A)	reactant	
B)	product	
C)	catalyst	
D)	reaction intermediate	
E)	activated complex	

ANS:	D	PTS:	1	DIF:	Easy	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | elementary reaction	MSC:	Conceptual

	103.	The rate law for a reaction is found to be Rate = k[A]2[B]. Which of the following mechanisms gives this rate law?

I.	A + BE (fast)	
	E + B ® C + D (slow)	
II.	A + BE (fast)	
	E + A ® C + D (slow)	
III.	A + A ® E (slow).	
	E + B ® C + D (fast)	

A)	I	
B)	II	
C)	III	
D)	two of these	
E)	none of these	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism	MSC:	Conceptual

	104.	The experimental rate law for the decomposition of nitrous oxide (N2O) to N2 and O2 is Rate = k[N2O]2. Two mechanisms are proposed:
I.	N2O ® N2 + O	
	N2O + O ® N2 + O2	
II.	2N2O  N4O2	
	N4O2 ® 2N2 + O2	
Which of the following could be a correct mechanism?
A)	Mechanism I, with the first step as the rate-determining step.	
B)	Mechanism I, with the second step as the rate-determining step as long as the first step is a fast equilibrium step.	
C)	Mechanism II, with the second step as the rate-determining step if the first step is a fast equilibrium step.	
D)	None of the choices (A-C) could be correct.	
E)	At least two of the above choices (A-C) could be correct.	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism	MSC:	Conceptual

	105.	Consider the reaction 2O3(g) ® 3O2(g). The following mechanism is proposed:
                    O3  O2 + O
                    O3 + O ® 2O2
If we assume the second step of the mechanism is the rate determining step and the first step is a fast equilibrium step, which of the following rate laws is predicted by this mechanism?
A)	rate = k[O3]	
B)	rate = k[O3]2[O2]	
C)	rate = k[O3]2[O2]–1	
D)	rate = k[O3]2	
E)	none of these	

ANS:	C	PTS:	1	DIF:	Moderate	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism	MSC:	Conceptual

	106.	Of what use is it to find a rate law for a reaction?
A)	We can use the rate law to directly determine coefficients in the balanced equation.	
B)	From the rate law we can evaluate potential reaction mechanisms.	
C)	The rate law gives us a good indication of the thermodynamic stability of the products.	
D)	The rate law can lead us to determine the equilibrium constant for the reaction.	
E)	None of these.	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism	MSC:	Conceptual

The following questions refer to the reaction 2A2 + B2 ® 2C. The following mechanism has been proposed:
	step 1 (very slow)		A2 + B2 ® R + C	
	step 2 (slow)		A2 + R ® C	

	107.	What is the molecularity of step 2?
A)	unimolecular	
B)	bimolecular	
C)	termolecular	
D)	quadmolecular	
E)	molecularity cannot be determined	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | elementary reaction | molecularity		MSC:	Conceptual

	108.	Which step is rate determining?
A)	both steps	
B)	step 1	
C)	step 2	
D)	a step that is intermediate to step 1 and step 2	
E)	none of these	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism | rate determining step	MSC:	Conceptual

	109.	According to collision theory, the activated complex that forms in step 1 could have which of the following structures? (The dotted lines represent partial bonds.)
A)		
B)		
C)		
D)		
E)		

ANS:	B	PTS:	1	DIF:	Moderate	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | collision theory | activated complex	MSC:	Conceptual

	110.	According to the proposed mechanism, what should the overall rate law be?
A)	rate = k[A2]2	
B)	rate = k[A2]	
C)	rate = k[A2][B2]	
D)	rate = k[A2][R]	
E)	rate = k[R]2	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism	MSC:	Conceptual

Under certain conditions the reaction H2O2 + 3I– + 2H+ ® I3– + 2H2O occurs by the following series of steps:
	k1	
	Step 1.		H2O2 + H+ H3O2+	
	k–1	
     
	Step 2.		H3O2+ + I– ® H2O + HOI	(slow, rate constant k2)	
	Step 3.		HOI + I– ® OH– + I2	(fast, rate constant k3)	
	Step 4.		OH– + H+ ® H2O	(fast, rate constant k4)	
	Step 5.		I2 + I– ® I3–	(fast, rate constant k5)	

	111.	Which of the steps would be called the rate-determining step?
A)	1	
B)	2	
C)	3	
D)	4	
E)	5	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism | rate determining step	MSC:	Conceptual

	112.	The rate constant k for the reaction would be given by
A)	k = k2	
B)	k = k2k3	
C)	k = k2K	
D)	k = k5	
E)	k = Kk2k3k4k5	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism	MSC:	Conceptual

	113.	The rate law for the reaction would be:
A)	D[I3]/Dt = k[H2O2]	
B)	D[I3]/Dt = k[H2O2][H+][I–]	
C)	D[I3]/Dt = k[H2O2][H+]	
D)	D[I3]/Dt = k[H2O2][I–]	
E)	D[I3]/Dt = k[H2O2][H+]2[I–]–3	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism	MSC:	Conceptual

	114.	The reaction:
	2A + B ® C	
has the following proposed mechanism:	
	Step 1:    A + BD (fast equilibrium)	
	Step 2:    D + B ® E	
	Step 3:    E + A ® C + B	
If step 2 is the rate-determining step, then the rate of formation of C should equal:
A)	k[A]	
B)	k[A]2[B]	
C)	k[A]2[B]2	
D)	k[A][B]	
E)	k[A][B]2	

ANS:	E	PTS:	1	DIF:	Easy	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism | rate determining step	MSC:	Conceptual

	115.	The reaction 2NO + O2 ® 2NO2 obeys the rate law  – = kobsd[NO]2[O2].
Which of the following mechanisms is consistent with the experimental rate law?
A)	NO + NO ® N2O2        (slow)
N2O2 + O2 ® 2NO2      (fast)	
B)	NO + O2NO3     (fast equilibrium)
NO3 + NO ® 2NO2       (slow)	
C)	2NON2O2           (fast equilibrium)
N2O2 ® NO2 + O         (slow)
NO + O ® NO2            (fast)	
D)	O2 + O2 ® O2 + O2       (slow)
O2 + NO ® NO2 + O    (fast)
O + NO ® NO2             (fast)	
E)	none of these	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.5
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism	MSC:	Conceptual

	116.	The rate constant k is dependent on
I.	the concentration of the reactant	
II.	the nature of the reactants	
III.	the temperature	
IV.	the order of the reaction	

A)	none of these	
B)	one of these	
C)	two of these	
D)	three of these	
E)	all of these	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | collision theory
MSC:	Conceptual

The questions below refer to the following diagram:

	117.	Why is this reaction considered to be exothermic?
A)	Because energy difference B is greater than energy difference C.	
B)	Because energy difference B is greater than energy difference A.	
C)	Because energy difference A is greater than energy difference C.	
D)	Because energy difference B is greater than energy difference C plus energy difference A.	
E)	Because energy difference A and energy difference C are about equal.	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | collision theory
MSC:	Conceptual

	118.	At what point on the graph is the activated complex present?
A)	point W	
B)	point X	
C)	point Y	
D)	point Z	
E)	none of these	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | collision theory | activated complex	MSC:	Conceptual

	119.	If the reaction were reversible, would the forward or the reverse reaction have a higher activation energy?
A)	The diagram shows no indication of any activation energy.	
B)	The forward and reverse activation energies are equal.	
C)	The forward activation energy would be greater.	
D)	The reverse activation energy would be greater.	
E)	None of these.	

ANS:	D	PTS:	1	DIF:	Easy	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | collision theory | activation energy	MSC:	Conceptual

	120.	What would happen if the kinetic energy of the reactants was not enough to provide the needed activation energy?
A)	The products would be produced at a lower energy state.	
B)	The rate of the reaction would tend to increase.	
C)	The activated complex would convert into products.	
D)	The reactants would continue to exist in their present form.	
E)	The products would form at an unstable energy state.	

ANS:	D	PTS:	1	DIF:	Easy	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | collision theory | activation energy	MSC:	Conceptual

	121.	The rate constant for a reaction at 40.0°C is exactly 3 times that at 20.0°C. Calculate the Arrhenius energy of activation for the reaction.
A)	9.13 kJ/mol	
B)	5.04 kJ/mol	
C)	41.9 kJ/mol	
D)	3.00 kJ/mol	
E)	none of these	

ANS:	C	PTS:	1	DIF:	Moderate	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | Arrhenius equation
MSC:	Quantitative

Use the potential energy diagram shown to answer the following:

	122.	Which letter shows the activation energy (without use of a catalyst)?
A)	a	
B)	b	
C)	c	
D)	d	
E)	e	

ANS:	A	PTS:	1	DIF:	Easy	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | collision theory | activation energy	MSC:	Conceptual

	123.	Which letter shows the change in energy for the overall reaction?
A)	a	
B)	b	
C)	c	
D)	d	
E)	e	

ANS:	D	PTS:	1	DIF:	Easy	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | collision theory
MSC:	Conceptual

	124.	Which letter shows the activation energy using a catalyst?
A)	a	
B)	b	
C)	c	
D)	d	
E)	e	

ANS:	E	PTS:	1	DIF:	Easy	REF:	12.7
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | collision theory | activation energy	MSC:	Conceptual

The questions below refer to the following information: The rate constant k for the reaction shown below is 2.6 ´ 10–8 L/mol × s when the reaction proceeds at 300.0 K. The activation energy is 98000 J/mol. (The universal gas constant, R, is 8.314 J/mol·K)
	2NOCl ® 2NO + Cl2	

	125.	Determine the magnitude of the frequency factor for the reaction.
A)	1.2 ´ 108	
B)	4.6 ´ 109	
C)	3.0 ´ 109	
D)	2.7 ´ 108	
E)	9.1 ´ 109	

ANS:	C	PTS:	1	DIF:	Moderate	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | Arrhenius equation
MSC:	Quantitative

	126.	If the temperature changed to 310 K, the rate constant k would change. The ratio of k at 310 K to k at 300.0 K is closest to what whole number?
A)	1	
B)	2	
C)	3	
D)	4	
E)	5	

ANS:	D	PTS:	1	DIF:	Difficult	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | Arrhenius equation
MSC:	Quantitative

	127.	Use the following information to determine the activation energy for the reaction shown here:

Temperature
(K)	Rate Constant
(L/mol·s)	
1400	0.143	
1500	0.685	

A)	 J/mol	
B)	 J/mol	
C)	 J/mol	
D)	 J/mol	
E)	 J/mol	

ANS:	E	PTS:	1	DIF:	Moderate	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | Arrhenius equation
MSC:	Quantitative

	128.	When ethyl chloride, CH3CH2Cl, is dissolved in 1.0 M NaOH, it is converted into ethanol, CH3CH2OH, by the reaction:

At 25°C the reaction is first order in CH3CH2Cl, and the rate constant is 3.1 ´ 10–3 s–1. If the activation parameters are A = 3.4 ´ 1014 s–1 and Ea = 100.0 kJ/mol, what will the rate constant be at 40.°C?
A)	 s–1	
B)	 s–1	
C)	 s–1	
D)	 s–1	
E)	 s–1	

ANS:	A	PTS:	1	DIF:	Moderate	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | Arrhenius equation
MSC:	Quantitative

	129.	Which of the following statements best describes the condition(s) needed for a successful formation of a product according to the collision model?
A)	The collision must involve a sufficient amount of energy, provided from the motion of the particles, to overcome the activation energy.	
B)	The relative orientation of the particles has little or no effect on the formation of the product.	
C)	The relative orientation of the particles has an effect only if the kinetic energy of the particles is below some minimum value.	
D)	The relative orientation of the particles must allow for formation of the new bonds in the product.	
E)	The energy of the incoming particles must be above a certain minimum value, and the relative orientation of the particles must allow for formation of new bonds in the product.	

ANS:	E	PTS:	1	DIF:	Easy	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | collision theory
MSC:	Conceptual

	130.	The rate constant for a reaction is 1.5 ´ 10–2 s–1 at 734 K and 3.9 ´ 10–2 s–1 at 878 K. What is the activation energy?
A)	15 kJ/mol	
B)	36 kJ/mol	
C)	440 kJ/mol	
D)	4300 kJ/mol	
E)	This can't be solved without knowing the frequency factor.	

ANS:	B	PTS:	1	DIF:	Moderate	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | Arrhenius equation
MSC:	Quantitative

	131.	For the second-order reaction NO(g) + O3(g) ® NO2(g) + O2(g), the rate constant has been measured to be 1.08 ´ 107 M–1 s–1 at 298 K and the activation energy has been measured to be 11.4 kJ/mol over the temperature range 195 K to 304 K. What is the rate constant at 233 K? (R = 8.3145 J K–1 mol–1)
A)	 M–1 s–1	
B)	 M–1 s–1	
C)	 M–1 s–1	
D)	 M–1 s–1	
E)	 M–1 s–1	

ANS:	C	PTS:	1	DIF:	Difficult	REF:	12.6
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | Arrhenius equation
MSC:	Quantitative

	132.	The reaction 2H2O2 ® 2H2O + O2 has the following mechanism:
H2O2 + I– ® H2O + IO–		
H2O2 + IO– ® H2O + O2 + I–		
The catalyst in the reaction is:
A)	H2O	
B)	I–	
C)	H2O2	
D)	IO–	
E)	There is no catalyst in this reaction.	

ANS:	B	PTS:	1	DIF:	Easy	REF:	12.7
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | catalysis
MSC:	Conceptual

	133.	Which of the following statements is typically true for a catalyst?
I.	The concentration of the catalyst will go down as a reaction proceeds.	
II.	The catalyst provides a new pathway in the reaction mechanism.	
III.	The catalyst speeds up the reaction.	

A)	I only	
B)	II only	
C)	III only	
D)	I and III	
E)	II and III	

ANS:	E	PTS:	1	DIF:	Easy	REF:	12.7
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | catalysis
MSC:	Conceptual

	134.	The catalyzed pathway in a reaction mechanism has a __________ activation energy and thus causes a __________ reaction rate.
A)	higher, lower	
B)	higher, higher	
C)	lower, higher	
D)	lower, steady	
E)	higher, steady	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.7
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | catalysis
MSC:	Conceptual

	135.	Which of the following statements about enzymes is incorrect?
A)	They are proteins that catalyze specific biologic reactions.	
B)	Several hundred are now known.	
C)	The molecules they react with are called substrates.	
D)	They are equal to inorganic catalysts in efficiency.	
E)	All of these are correct.	

ANS:	D	PTS:	1	DIF:	Moderate	REF:	12.7
KEY:	Chemistry | general chemistry | rates of reaction | reaction mechanism | catalysis | enzyme catalysis	MSC:	Conceptual

	136.	Determine (a) the rate equation and (b) the rate constant for the hypothetical reaction A + B ® C given the following initial concentrations and initial rate data.
		[A]0	[B]0	Initial Rate	
	Run #	(mol/L)	(mol/L)	(mol/L·s)	
	(1)	0.100	0.100	0.18	
	(2)	0.100	0.200	0.36	
	(3)	0.200	0.200	1.44	

ANS:	
a)  rate = k[A]2[B]     (b) 1.8 ´ 102 L2/mol2s

a)  Use method of initial rates to solve for exponents:
     
     4 = [2]n; n = 2
     
     2 = [2]m; m = 1
     Therefore the rate law is: rate = k[A]2[B]

b)  To solve for k, use any set of experimental conditions in the rate law:
     0.18 mol/L·s = k(0.100 mol/L)2(0.100 mol/L)
     k = 0.18 mol/L·s / (0.100)3 mol3/L3;  k = 1.8 ´ 102 L2/mol2s

PTS:	1	DIF:	Moderate	REF:	12.3	
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration	MSC:	Quantitative

A reaction represented by the equation was studied at a specific temperature and the following data were collected:
                  3O2 (g) ® 2O3 (g)
 Time (seconds)	Total pressure (atm)	
0	1.000	
 46.89	0.9500	
 98.82	0.9033	
 137.9	0.8733	
 200.0	0.8333	
 286.9	0.7900	
 337.9	0.7700	
 511.3	0.7233	

	137.	What is the rate law for this reaction?

ANS:	
rate = k[O2]

Data given represents "total pressure," so it must be adjusted to consider only .
                   3O2 ® 2O3
Before        1.000          0
Change       -3x           +2x
After        1.000 – 3x       2x
Total P = 1.000 – 3x + 2x = 1.000 – x
At t=46.89, P = 1.000 – x = 0.9500; x = 0.0500
Thus, PO2 = 1.000 – 3(0.0500) = 0.0850
The corrected table is:
 Time (seconds)	Total pressure (atm)	
0	1.000	
 46.89	0.850	
 98.82	0.710	
 137.9	0.620	
 200.0	0.500	
 286.9	0.370	
 337.9	0.310	
 511.3	0.170	
This data will give a straight-line plot for  versus time, indicating the reaction is first-order in O2.

PTS:	1	DIF:	Moderate	REF:	12.4	
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data		MSC:	Conceptual

	138.	What is the value of the rate constant?

ANS:	
k = 3.47 x 10–3 sec–1

This is the slope of the straight line resulting from graph of  versus time (see answer to previous problem).

PTS:	1	DIF:	Moderate	REF:	12.4	
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data		MSC:	Quantitative

	139.	How many seconds would it take for the total pressure to be 0.7133 atm?

ANS:	
567 s

Total pressure of 0.7133 atm must be corrected to reflect  only (see answer to #123).
1.000-x = 0.7133; x = 0.287
1.000-3(0.287) = 0.140 atm
(k = 0.00347 sec–1 from previous problem)
ln(0.140) = –0.00347t + ln(1.000);  t = 567 s

PTS:	1	DIF:	Moderate	REF:	12.4	
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data		MSC:	Quantitative

For the reaction aA ® Products, use the following choices
a)  zero order in A
b)  first order in A
c)  second order in A
d)  a, b, c
e)  none of the above

	140.	The half-life is constant.

ANS:	
b

For a first-order reaction, the half-life is not dependent on concentration, but it is for zero-order and second-order reactions.
See Sec 12.4, Zumdahl Chemistry.

PTS:	1	DIF:	Easy	REF:	12.4	
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction			MSC:	Conceptual

	141.	A plot of [A] vs. t is a straight line.

ANS:	
a

The integrated rate law for a zero-order reaction is: [A] = -kt + [A]0
See Sec 12.4, Zumdahl Chemistry.

PTS:	1	DIF:	Moderate	REF:	12.4	
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data		MSC:	Conceptual

	142.	[A] is constant.

ANS:	
e

[A] is the amount of reactant at any time during the reaction. If [A] is constant then there is no reaction occurring.
See Sec. 12.4, Zumdahl Chemistry.

PTS:	1	DIF:	Easy	REF:	12.4	
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws
MSC:	Conceptual

	143.	The rate is constant over time.

ANS:	
a

For a zero-order reaction, the rate law only depends on k, and not at all on the amount of reactant present, so it is constant.
See Sec. 12.4, Zumdahl Chemistry.

PTS:	1	DIF:	Easy	REF:	12.4	
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws
MSC:	Conceptual

	144.	Consider the reaction, 3 A + 5 B   4 C + 7 D.  If C is being produced at a rate of  2.43 mol/L s, at what rate is [A] decreasing?
A)	1.82 mol/L s	
B)	3.24 mol/L s	
C)	3.6 mol/L s	
D)	–1.82 mol/L s	
E)	2.43 mol/L s	

ANS:	A	PTS:	1	DIF:	Easy	REF:	12.1
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate	
MSC:	Quantitative

	145.	Consider the reaction, 3 A + 5 B  ® 4 C + 7 D.  If C is being produced at a rate of  1.96 mol/L s, at what rate is [D] increasing?
A)	3.43 mol/L s	
B)	1.12 mol/L s	
C)	2.1 mol/L s	
D)	–3.43 mol/L s	
E)	1.96 mol/L s	

ANS:	A	PTS:	1	DIF:	Easy	REF:	12.1
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate	
MSC:	Quantitative

	146.	The rate law of a particular reaction is found to be, rate = k[A]2[B].  Which of the following statements is FALSE?
A)	The reaction is third order overall.	
B)	The units of k could be (L2/mol2 s)	
C)	Tripling the concentration of A will result in a nine-fold increase in the rate.	
D)	The actual value of k will depend on the temperature	
E)	The actual value of k will depend on the concentrations of A and B.	

ANS:	E	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | rate law		MSC:	Conceptual

	147.	The following data were obtained for the reaction, C + D + E  ® products.  Determine the rate law.

Initial [C] mol/L	Initial [D] mol/L	Initial [E] mol/L		Initial rate (mol/Ls)

0.15			0.22			0.34				5.11 x 10-3
0.30			0.22			0.34				1.02 x 10-2
0.45			0.33			0.34				2.30 x 10-2
0.30			0.22			0.68				1.03 x 10-2
A)	rate = k[C][D][E]	
B)	rate = k[C]2[D]	
C)	rate = k[C][D]	
D)	rate = k[C][E]	
E)	rate = k[E][D]	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining rate law	MSC:	Conceptual

	148.	The following data were obtained for the reaction, C + D + E ® products.  Determine the value of k (do not include units)

Initial [C] mol/L	Initial [D] mol/L	Initial [E] mol/L		Initial rate (mol/Ls)

0.15			0.22			0.34				5.11 x 10-3
0.30			0.22			0.34				1.02 x 10-2
0.45			0.33			0.34				2.30 x 10-2
0.30			0.22			0.68				1.03 x 10-2
A)	0.46	
B)	0.23	
C)	0.15	
D)	0.10	
E)	0.068	

ANS:	C	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining rate law	MSC:	Quantitative

	149.	The following data were obtained for the reaction, C + D + E  ® products.  Determine the units of k.

Initial [C] mol/L	Initial [D] mol/L	Initial [E] mol/L		Initial rate (mol/Ls)

0.15			0.22			0.34				5.11 x 10-3
0.30			0.22			0.34				1.02 x 10-2
0.45			0.33			0.34				2.30 x 10-2
0.30			0.22			0.68				1.03 x 10-2
A)	mol/L	
B)	mol/L·s	
C)	1/s	
D)	L/mol·s	
E)	L2/mol2·s	

ANS:	D	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining rate law	MSC:	Conceptual

	150.	Determine the rate law for the reaction: C2H4Br2 + 3KI ® C2H4 + 2KBr +KI3, given the initial rate data below?
[C2H4Br2], M		[KI], M		D[KI3]/Dt (M min-1)
    0.500		 1.80			     0.269
    0.500		 7.20			     1.08
    1.50			 1.80			     0.807
A)	rate = k[KI]	
B)	rate = k[C2H4Br2]	
C)	rate = k[KI]2	
D)	rate = k[KI][C2H4Br2]	
E)	rate = k[KI][C2H4Br2]2	

ANS:	D	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining rate law	MSC:	Conceptual

	151.	Determine the value of k (without units) for the reaction: C2H4Br2 + 3KI ® C2H4 + 2KBr +KI3, given the initial rate data below?
[C2H4Br2], M		[KI], M		D[KI3]/Dt (M min-1)
    0.500		 1.80			     0.269
    0.500		 7.20			     1.08
    1.50			 1.80			     0.807
A)	0.149	
B)	0.538	
C)	0.0830	
D)	0.299	
E)	0.598	

ANS:	D	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining rate law	MSC:	Quantitative

	152.	Determine the units of k for the reaction: C2H4Br2 + 3KI ® C2H4 + 2KBr +KI3, given the initial rate data below?
[C2H4Br2], M		[KI], M		D[KI3]/Dt (M s-1)
    0.500		 1.80			     0.269
    0.500		 7.20			     1.08
    1.50			 1.80			     0.807
A)	mol/L	
B)	mol/L·s	
C)	1/s	
D)	L/mol·s	
E)	L2/mol2·s	

ANS:	D	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining rate law	MSC:	Conceptual

	153.	Which statement is true about the reaction 2A® B + C which is first order in A and first order overall?
A)	The rate of the reaction will decrease at higher concentrations of B and C.	
B)	The time required for one half of A to react is directly proportional to the quantity of A.	
C)	The rate of formation of C is twice the rate of reaction of A.	
D)	The rate of formation of B is the same as the rate of reaction of A.	
E)	The concentration of A will decrease exponentially.	

ANS:	E	PTS:	1	DIF:	Easy	REF:	12.3
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | rate law		MSC:	Conceptual

	154.	The first-order decomposition of H2O2 at -30 °C occurs with a half-life of 42.0 seconds.  What will be the residual concentration of 10.2 mol/L H2O2 after 3 minutes?
A)	0.326 mol/L	
B)	0.523 mol/L	
C)	8.73 mol/L	
D)	9.71 mol/L	
E)	11.9 mol/L	

ANS:	B	PTS:	1	DIF:	Difficult	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction	MSC:	Quantitative

	155.	The dimerization of NO2 has a rate constant at 25 °C of 2.45 x 10-2 L/mol min.  What will be the concentration of NO2 after 120. seconds, given a starting concentration of NO2 of 11.5 mol/L?
A)	0.331 mol/L	
B)	0.608 mol/L	
C)	7.36 mol/L	
D)	10.95 mol/L	
E)	12.1 mol/L	

ANS:	C	PTS:	1	DIF:	Difficult	REF:	12.4
KEY:	Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | second-order reaction			MSC:	Quantitative