Q: Given the following data for the reaction $$\mathrm{BF_3$ (g) + NH_3$ (g) \rightarrow F_3BNH_3 (g)}$$, what is the correct rate law for the reaction? Experiment | [BF$$_3$$] (M) | [NH$$_3$$] (M) | Initial Rate (M/s) ---|---|---|--- 1 | 0.250 | 0.250 | 0.2130 2 | 0.250 | 0.125 | 0.1065 3 | 0.200 | 0.100 | 0.0682 4 | 0.350 | 0.100 | 0.1193 5 | 0.175 | 0.100 | 0.0596

$$\text{Rate} = k[\mathrm{BF_3$}][\mathrm{NH_3$}]$$

Q: For the reaction $$\mathrm{2NO(g) + Br_2$(g) \rightarrow 2NOBr(g)}$$, how is the rate of disappearance of Br$$_2$$ related to the rate of appearance of NOBr?

$$\text{Rate of disappearance of Br}_2 = \frac{1}{2} \times \text{Rate of appearance of NOBr}$$

Q: For the reaction $$\mathrm{2NO(g) + O_2$(g) \rightarrow 2NO_2(g)}$$, if $$[\mathrm{NO}] = 0.0750\ \mathrm{M}$$ and $$[\mathrm{O}_2] = 0.0100\ \mathrm{M}$$, and $$k = 1.00\ \mathrm{M$$^{-2}$$ s$$^{-1}$$}$$, what is the rate of disappearance of O$$_2$$?

$$2.81 \times 10$$^{-3}$$\ \mathrm{M/s}$$

Q: For the reaction $$\mathrm{S_2O_8$$^{2-}$$ (aq) + 3I^- (aq) \rightarrow 2SO_4$$^{2-}$$ (aq) + I_3$^- (aq)}$$, how is the rate of disappearance of $$\mathrm{S_2O_8$$^{2-}$$}$$ related to the rate of appearance of $$\mathrm{I_3$^-}$$?

$$\text{Rate of disappearance of } \mathrm{S_2O_8$$^{2-}$$} = \text{Rate of appearance of } \mathrm{I_3$^-}$$

Question 1

Given the following data for the reaction $$\mathrm{BF_3$ (g) + NH_3$ (g) \rightarrow F_3BNH_3 (g)}$$, what is the correct rate law for the reaction?

Experiment | [BF$$_3$$] (M) | [NH$$_3$$] (M) | Initial Rate (M/s)
---|---|---|---
1 | 0.250 | 0.250 | 0.2130
2 | 0.250 | 0.125 | 0.1065
3 | 0.200 | 0.100 | 0.0682
4 | 0.350 | 0.100 | 0.1193
5 | 0.175 | 0.100 | 0.0596

Accepted Answer

$$	ext{Rate} = k[\mathrm{BF_3$}][\mathrm{NH_3$}]$$

Question 2

For the reaction $$\mathrm{2NO(g) + O_2$(g) ightarrow 2NO_2(g)}$$, the following data were collected:

Experiment | [NO] (M) | [O$$_2$$] (M) | Initial Rate (M/s)
---|---|---|---
1 | 0.0126 | 0.0125 | $$1.41 	imes 10$$^{-2}$$
2 | 0.0252 | 0.0125 | 5.64$$ 	imes $$10^{-2}
3$$ | 0.0252 | 0.0250 | $$1.13 	imes 10$$^{-1}$$

What is the order of the reaction with respect to NO?

Accepted Answer

Second order

Question 3

For the reaction $$\mathrm{2NO(g) + Br_2$(g) \rightarrow 2NOBr(g)}$$, the following data were obtained:

Experiment | [NO] (M) | [Br$$_2$$] (M) | Initial Rate (M/s)
---|---|---|---
1 | 0.10 | 0.20 | 24
2 | 0.25 | 0.20 | 150
3 | 0.10 | 0.50 | 60
4 | 0.35 | 0.50 | 735

What is the overall order of the reaction?

Accepted Answer

Third order

Question 4

For the reaction $$\mathrm{2NO(g) + O_2$(g) ightarrow 2NO_2(g)}$$, what are the units of the rate constant $$k if $$the rate law is $$	ext{Rate} = k[\mathrm{NO}]^2[\mathrm{O}_2]$$?

Accepted Answer

$$\mathrm{M$$^{-2}$$ \cdot s$$^{-1}$$}$$

Question 5

Given the following data for the reaction $$\mathrm{S_2O_8$$^{2-}$$ (aq) + 3I^- (aq) ightarrow 2SO_4$$^{2-}$$ (aq) + I_3$^- (aq)}$$:

Experiment | [S$$_2O$_8$$^{2-}$$] (M) | [I$$^-$$] (M) | Initial Rate (M/s)
---|---|---|---
1 | 0.018 | 0.036 | 2.63$$ 	imes $$10^{-5}
2$$ | 0.027 | 0.036 | $$3.94 	imes 10$$^{-5}$$
3 | 0.018 | 0.054 | 3.78$$ 	imes $$10^{-5}
4$$ | 0.027 | 0.072 | $$1.43 	imes 10$$^{-4}$$

What is the order of the reaction with respect to $$\mathrm{I^-}$$?

Accepted Answer

First order

Question 6

For the reaction $$\mathrm{BF_3$ (g) + NH_3$ (g) \rightarrow F_3BNH_3 (g)}$$, if $$k = 3.4\ \mathrm{M$$^{-1}$$ s$$^{-1}$$}$$, what is the rate when $$[\mathrm{BF_3$}] = 0.100\ \mathrm{M}$$ and $$[\mathrm{NH_3$}] = 0.500\ \mathrm{M}$$?

Accepted Answer

$$0.170\ \mathrm{M/s}$$

Question 7

For the reaction $$\mathrm{2NO(g) + Br_2$(g) \rightarrow 2NOBr(g)}$$, how is the rate of disappearance of Br$$_2$$ related to the rate of appearance of NOBr?

Accepted Answer

$$	ext{Rate of disappearance of Br}_2 = \frac{1}{2} 	imes 	ext{Rate of appearance of NOBr}$$

Question 8

For the reaction $$\mathrm{2NO(g) + O_2$(g) \rightarrow 2NO_2(g)}$$, if $$[\mathrm{NO}] = 0.0750\ \mathrm{M}$$ and $$[\mathrm{O}_2] = 0.0100\ \mathrm{M}$$, and $$k = 1.00\ \mathrm{M$$^{-2}$$ s$$^{-1}$$}$$, what is the rate of disappearance of O$$_2$$?

Accepted Answer

$$2.81 	imes 10$$^{-3}$$\ \mathrm{M/s}$$

Question 9

For the reaction $$\mathrm{S_2O_8$$^{2-}$$ (aq) + 3I^- (aq) \rightarrow 2SO_4$$^{2-}$$ (aq) + I_3$^- (aq)}$$, how is the rate of disappearance of $$\mathrm{S_2O_8$$^{2-}$$}$$ related to the rate of appearance of $$\mathrm{I_3$^-}$$?

Accepted Answer

$$	ext{Rate of disappearance of } \mathrm{S_2O_8$$^{2-}$$} = 	ext{Rate of appearance of } \mathrm{I_3$^-}$$

Question 10

A medical laboratory is monitoring the decomposition of a drug that follows the rate law $$	ext{Rate} = k[\mathrm{Drug}]^2. If $$the initial concentration is $$0.10\ \mathrm{M}$$ and after $$10$$ minutes the concentration is $$0.050\ \mathrm{M}$$, what is the value of the rate constant $$k (in$$ $$\mathrm{M$$^{-1}$$ $$min^{-1}$$}$$)?

Accepted Answer

$$2.0\ \mathrm{M$$^{-1}$$ $$min^{-1}$$}$$

Question 11

For the reaction $$\mathrm{2NO(g) + Br_2$(g) \rightarrow 2NOBr(g)}$$, if $$[\mathrm{NO}] = 0.075\ \mathrm{M}$$ and $$[\mathrm{Br}_2] = 0.25\ \mathrm{M}$$, and $$k = 400\ \mathrm{M$$^{-2}$$ s$$^{-1}$$}$$, what is the rate of appearance of NOBr?

Accepted Answer

$$0.56\ \mathrm{M/s}$$

Question 12

A student claims that for a reaction with the rate law $$	ext{Rate} = k[\mathrm{A}]^0[\mathrm{B}]^1$$, doubling the concentration of A will double the rate. Is this correct?

Accepted Answer

No, because the rate is independent of [A].

Question 13

For the reaction $$\mathrm{2NO(g) + O_2$(g) ightarrow 2NO_2(g)}$$, if the rate law is $$	ext{Rate} = k[\mathrm{NO}]^2[\mathrm{O}_2]$$, what happens to the rate if $$[\mathrm{NO}] is $$doubled and $$[\mathrm{O}_2] is $$halved?

Accepted Answer

The rate is doubled.

Question 14

A reaction has the rate law $$	ext{Rate} = k[\mathrm{A}]^2[\mathrm{B}]. If $$the initial rate is $$0.10\ \mathrm{M/s}$$ when $$[\mathrm{A}] = 0.20\ \mathrm{M}$$ and $$[\mathrm{B}] = 0.50\ \mathrm{M}$$, what will the rate be if $$[\mathrm{A}] is $$increased to $$0.40\ \mathrm{M}$$ and $$[\mathrm{B}] is $$decreased to $$0.25\ \mathrm{M}$$?

Accepted Answer

$$0.20\ \mathrm{M/s}$$

Question 15

For the reaction $$\mathrm{S_2O_8$$^{2-}$$ (aq) + 3I^- (aq) ightarrow 2SO_4$$^{2-}$$ (aq) + I_3$^- (aq)}$$, if the rate law is $$	ext{Rate} = k[\mathrm{S_2O_8$$^{2-}$$}][\mathrm{I^-}]$$, what is the effect on the rate if both $$[\mathrm{S_2O_8$$^{2-}$$}]$$ and $$[\mathrm{I^-}]$$ are tripled?

Accepted Answer

The rate increases by a factor of 9.

Question 16

A reaction is found to be first order in A and zero order in B. Which of the following graphs would yield a straight line?

Accepted Answer

Plot of $$\ln [A] vs. $$time

Chemical Kinetics: Rate Laws and Reaction Orders

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