Q: For the reaction $$2NO(g) + O_2$(g) \rightarrow 2NO_2(g)$$, initial rate data are collected. If doubling $$[NO]$$ quadruples the rate and doubling $$[O_2$]$$ doubles the rate, what is the rate law?

$$\text{Rate} = k[NO]^2[O_2$]$$

Q: In the reaction $$2Fe^{2+}(aq$$) + $$Cl_2(aq$$) \rightarrow $$2Fe^{3+}(aq) + 2Cl^-(aq$$)$$, the rate doubles when $$[$$Fe^{2+}$$]$$ doubles, and also doubles when $$[$$Cl_2$$]$$ doubles, but is unaffected by $$[H^+]$$. What is the rate law?

$$\text{Rate} = k[Fe$$^{2+}$$][Cl_2$]$$

Question 1

Which of the following graphs would be linear for a first-order reaction?

Accepted Answer

$$\ln{[A]} \, vs \, t$$

Question 2

A reaction has a rate constant with units of $$\mathrm{M/s}. $$What is the overall order of the reaction?

Accepted Answer

Zero order

Question 3

For the isomerization of cyclopropane to propene, the rate constant is $$9.2 \, \mathrm{s}^{-1}$$ and the initial concentration is $$6.00 \, \mathrm{M}. $$What is the concentration after $$1.00 \, \mathrm{s}$$? (Use the first-order integrated rate law.)

Accepted Answer

Question 4

Which statement best describes the effect of temperature on the rate constant according to collision theory?

Accepted Answer

The rate constant increases exponentially with temperature due to more collisions having sufficient energy.

Question 5

Given the Arrhenius equation $$k = Ae$$^{-\frac{E_a}$${RT}}$$, what does $$A$$ represent?

Accepted Answer

Frequency factor

Question 6

A reaction has a half-life that doubles as the reaction proceeds. What is the most likely order of the reaction?

Accepted Answer

Second order

Question 7

For the reaction $$2NO(g) + O_2$(g) \rightarrow 2NO_2(g)$$, initial rate data are collected. If doubling $$[NO]$$ quadruples the rate and doubling $$[O_2$]$$ doubles the rate, what is the rate law?

Accepted Answer

$$	ext{Rate} = k[NO]^2[O_2$]$$

Question 8

In the reaction $$2Fe^{2+}(aq$$) + $$Cl_2(aq$$) \rightarrow $$2Fe^{3+}(aq) + 2Cl^-(aq$$)$$, the rate doubles when $$[$$Fe^{2+}$$]$$ doubles, and also doubles when $$[$$Cl_2$$]$$ doubles, but is unaffected by $$[H^+]$$. What is the rate law?

Accepted Answer

$$	ext{Rate} = k[Fe$$^{2+}$$][Cl_2$]$$

Question 9

Which of the following best describes the role of molecular orientation in the reaction between NO and Cl$$_2$$?

Accepted Answer

Proper orientation is required for bond formation; only collisions with the N atom of NO toward Cl$$_2$$ are effective.

Question 10

For a second-order reaction, which of the following is the correct integrated rate law?

Accepted Answer

$$\dfrac{1}{[A]_t} = kt + \dfrac{1}{[A]_0}$$

Question 11

A potential energy diagram for a reaction shows the reactants at a lower energy than the products. What type of reaction is this?

Accepted Answer

Endothermic

Question 12

The fraction of collisions with sufficient energy to react is given by $$f = e$$^{-\frac{E_a}$${RT}}. $$What happens to $$f as $$temperature increases?

Accepted Answer

$$f$$ increases exponentially

Question 13

For a first-order reaction, what is the formula for the half-life?

Accepted Answer

$$t_{1/2} = \dfrac{0.693}{k}$$

Question 14

If the rate law for a reaction is $$	ext{Rate} = k[Q]^0[R]^2$$, how should it be more typically written?

Accepted Answer

$$	ext{Rate} = k[R]^2$$

Question 15

For the reaction $$2NO_2(g) + F_2$(g) ightarrow 2NO_2F(g)$$ with rate law $$	ext{Rate} = k[NO_2$][F_2$]$$, what is the overall order?

Accepted Answer

Second order

Question 16

A reaction has $$E_a = 251 \, \mathrm{kJ/mol}$$ and $$\Delta H = +167 \, \mathrm{kJ/mol}. $$What is the activation energy for the reverse reaction?

Accepted Answer

$$E_a = 84 \, \mathrm{kJ/mol}$$

Question 17

Which of the following is the correct form of the Arrhenius equation for comparing rate constants at two temperatures?

Accepted Answer

$$\ln{\left(\dfrac{k_2$}{k_1$}\right)} = \dfrac{E_a}{R}\left(\dfrac{1}{T_1$} - \dfrac{1}{T_2$}\right)$$

Question 18

In a real-world scenario, a physician finds that doubling the number of cigarettes smoked per day quadruples the rate of aging. What is the exponent of the smoking term in the rate law?

Accepted Answer

2

Chemical Kinetics: Reaction Rates, Rate Laws, and Temperature Dependence

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