Q: Which of the following graphs would yield a straight line for a first-order reaction?

$\ln([\text{reactant}])$ vs. time

Q: A reaction is found to have an activation energy of $38.0\ \text{kJ/mol}$. If the rate constant for this reaction is $1.60 \times 10^4\ \text{M}^{-1}\text{s}^{-1}$ at $249\ \text{K}$, what is the rate constant at $436\ \text{K}$?

$4.38 \times 10^6\ \text{M}^{-1}\text{s}^{-1}$

Q: A reaction mixture at $50^\circ\text{C}$ has a rate constant of $4.8\ \text{L}\cdot\text{mol}^{-1}\cdot\text{s}^{-1}$. What is the value of the rate constant at $30^\circ\text{C}$ if the activation energy is $58.2\ \text{kJ/mol}$?

$0.84\ \text{L}\cdot\text{mol}^{-1}\cdot\text{s}^{-1}$

Question 1

Given the reaction $2NO_2(g) + O_2(g) ightarrow 2NO_3(g)$ and the following initial rate data:

$\begin{align*}
[NO_2] & : 0.030,\ 0.030,\ 0.060 \
[O_2] & : 0.0055,\ 0.0110,\ 0.0055 \
	ext{Initial Rate} (M/s) & : 8.55 	imes 10^{-3},\ 1.71 	imes 10^{-2},\ 3.42 	imes 10^{-2}
\end{align*}$

What is the correct rate law for this reaction?

Accepted Answer

$	ext{Rate} = k[NO_2]^2[O_2]$

Question 2

The second-order decomposition of HI has a rate constant of $1.80 	imes 10^{-3}\ 	ext{M}^{-1}	ext{s}^{-1}$. How much HI remains after $27.3\ 	ext{s}$ if the initial concentration is $4.78\ 	ext{M}$?

Accepted Answer

$2.39\ 	ext{M}$

Question 3

The second-order decomposition of $NO_2$ has a rate constant of $0.255\ 	ext{M}^{-1}	ext{s}^{-1}$. How much $NO_2$ decomposes in $4.00\ 	ext{s}$ if the initial concentration of $NO_2$ (1.00 L volume) is $1.33\ 	ext{M}$?

Accepted Answer

$0.77\ 	ext{mol}$

Question 4

A reaction is found to have an activation energy of $108\ 	ext{kJ/mol}$. If the rate constant for this reaction is $4.60 	imes 10^{-5}\ 	ext{s}^{-1}$ at $275\ 	ext{K}$, what is the rate constant at $366\ 	ext{K}$?

Accepted Answer

$1.72\ 	ext{s}^{-1}$

Question 5

Which of the following graphs would yield a straight line for a first-order reaction?

Accepted Answer

$\ln([	ext{reactant}])$ vs. time

Question 6

How many half-lives are required for the concentration of reactant to decrease to $3.12\%$ of its original value?

Accepted Answer

4

Question 7

A reaction is found to have an activation energy of $38.0\ 	ext{kJ/mol}$. If the rate constant for this reaction is $1.60 	imes 10^4\ 	ext{M}^{-1}	ext{s}^{-1}$ at $249\ 	ext{K}$, what is the rate constant at $436\ 	ext{K}$?

Accepted Answer

$4.38 	imes 10^6\ 	ext{M}^{-1}	ext{s}^{-1}$

Question 8

Which is the correct equilibrium constant expression for the following reaction?

$FeO(s) + H_2(g) \rightarrow Fe(s) + H_2O(g)$

Accepted Answer

$K = [H_2O]/[H_2]$

Question 9

Consider the following reaction:

$CO(g) + 2H_2(g) ightarrow CH_3OH(g)$

A reaction mixture at $780\ ^\circ	ext{C}$ initially contains $[CO] = 0.50\ 	ext{M}$ and $[H_2] = 1.00\ 	ext{M}$. At equilibrium, the CO concentration is $0.15\ 	ext{M}$. What is the value of the equilibrium constant?

Accepted Answer

26

Question 10

Which statement is correct regarding the equilibrium constant $K$?

Accepted Answer

If $Q=K$, then the system is at equilibrium.

Question 11

For the following reaction at equilibrium, which choice gives a change that will shift the position of equilibrium to favor formation of more products?

$2NOBr(g) ightarrow 2NO(g) + Br_2(g)$

$\Delta H_{rxn} = +30\ 	ext{kJ/mol}$

Accepted Answer

Remove Br$_2$

Question 12

The decomposition of ethane ($C_2H_6$) to methyl radicals ($CH_3$) is a first-order reaction with a rate constant of $5.36 	imes 10^{-5}\ 	ext{s}^{-1}$ at $700^\circ	ext{C}$. Calculate the half-life of the reaction in minutes.

Accepted Answer

1290 min

Question 13

The rate constant for a reaction is $4.65\ 	ext{L}\cdot	ext{mol}^{-1}\cdot	ext{s}^{-1}$. What is the overall order of the reaction?

Accepted Answer

Second

Question 14

A reaction mixture at $50^\circ	ext{C}$ has a rate constant of $4.8\ 	ext{L}\cdot	ext{mol}^{-1}\cdot	ext{s}^{-1}$. What is the value of the rate constant at $30^\circ	ext{C}$ if the activation energy is $58.2\ 	ext{kJ/mol}$?

Accepted Answer

$0.84\ 	ext{L}\cdot	ext{mol}^{-1}\cdot	ext{s}^{-1}$

Question 15

The rate constant for the reaction $2A ightarrow B$ is $7.5 	imes 10^{-3}\ 	ext{s}^{-1}$ at $110^\circ	ext{C}$. The reaction is first order in $A$. How long (in seconds) will it take for $[A]$ to decrease from $1.25\ 	ext{M}$ to $0.71\ 	ext{M}$?

Accepted Answer

75 s

Question 16

For the reaction $CO_2(g) + 2H_2(g) ightarrow CH_4(g) + 2H_2O(g)$, $\Delta H = +890\ 	ext{kJ}$, what will happen if the temperature of the system is increased?

Accepted Answer

The equilibrium constant will increase.

Question 17

The equilibrium constant is given for one of the reactions below. Determine the value of the missing equilibrium constant.

$H_2(g) + Br_2(g) + 2HBr(g) \quad K_c = 3.8 	imes 10^1$

$2HBr(g) ightleftharpoons H_2(g) + Br_2(g) \quad K_c = ?$

Accepted Answer

$6.6 	imes 10^{-2}$

Question 18

Consider the following reaction at equilibrium. What effect will raising the pressure of the system from $5\ 	ext{atm}$ to $8\ 	ext{atm}$ have?

$2NH_3(g) ightleftharpoons N_2(g) + 3H_2(g)$

Accepted Answer

It will shift to the left

Question 19

For the reaction $I_2(g) + Cl_2(g) \rightleftharpoons 2ICl(g)$, which statement is correct if the equilibrium constant remains unchanged?

Accepted Answer

The equilibrium constant will remain constant and the reaction will proceed in the forward direction

Chemical Kinetics and Chemical Equilibrium: Study Notes

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