Q: A reaction has the following rate law: $$\text{Rate} = k[X]^2[Y]^3. If $$the concentration of X is tripled and Y is doubled, by what factor does the rate increase?

The rate increases by a factor of $$3^2$$ \times $$2^3 = 72$

Q: Which plot would yield a straight line for a second-order reaction with respect to [A]?

$$\frac{1}{[A]}$$ \text{ vs. } t$

Q: The decomposition of $$\text{N}_2\text{O}_5 is$$ $$2\text{N}_2\text{O}_5(g) \rightarrow 4\text{NO}_2(g) + \text{O}_2(g). If $$the rate of disappearance of $$\text{N}_2\text{O}_5 is$$ $$2.48 \times 10$$^{-4}$$ \ \mathrm{M/min}$$, what is the rate of formation of $$\text{NO}_2$$?

$$4.96 \times 10$$^{-4}$$ \ \mathrm{M/min}$$

Question 1

Which of the following best describes the rate law for a reaction that is first order in [A] and second order in [B]?

Accepted Answer

$$	ext{Rate} = k[A][B]^2$$

Question 2

A reaction has the following rate law: $$	ext{Rate} = k[X]^2[Y]^3. If $$the concentration of X is tripled and Y is doubled, by what factor does the rate increase?

Accepted Answer

The rate increases by a factor of $$3^2$$ 	imes $$2^3 = 72$

Question 3

For the reaction $$2	ext{NO}_2(g) ightarrow 2	ext{NO}(g) + 	ext{O}_2(g)$$, the rate law is found to be $$	ext{Rate} = k[	ext{NO}_2]^2. $$What are the units of the rate constant $$k$$?

Accepted Answer

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

Question 4

Given the reaction $$2	ext{H}_2(g) + 2	ext{NO}(g) ightarrow 2	ext{H}_2	ext{O}(g) + 	ext{N}_2(g)$$ with the rate law $$	ext{Rate} = k[	ext{NO}]^2[	ext{H}_2]$$, what is the overall order of the reaction?

Accepted Answer

Third order

Question 5

A first-order reaction has a half-life of 10 minutes. What fraction of the reactant remains after 30 minutes?

Accepted Answer

$$\left(\frac{1}{2}\$$right)^3$$ = \frac{1}{8}$$

Question 6

Which plot would yield a straight line for a second-order reaction with respect to [A]?

Accepted Answer

$$\frac{1}{[A]}$$ 	ext{ vs. } t$

Question 7

The decomposition of $$	ext{N}_2	ext{O}_5 is$$ $$2	ext{N}_2	ext{O}_5(g) ightarrow 4	ext{NO}_2(g) + 	ext{O}_2(g). If $$the rate of disappearance of $$	ext{N}_2	ext{O}_5 is$$ $$2.48 	imes 10$$^{-4}$$ \ \mathrm{M/min}$$, what is the rate of formation of $$	ext{NO}_2$$?

Accepted Answer

$$4.96 	imes 10$$^{-4}$$ \ \mathrm{M/min}$$

Question 8

Which of the following statements about the Arrhenius equation is correct?

Accepted Answer

The rate constant $$k$$ increases exponentially with increasing temperature.

Question 9

For a zero-order reaction, which of the following is true?

Accepted Answer

The rate is independent of the concentration of reactant.

Question 10

A reaction has the following data:
Trial 1: [A] = 0.125 M, [B] = 0.200 M, Rate = 7.25 M/min
Trial 2: [A] = 0.375 M, [B] = 0.200 M, Rate = 21.75 M/min
Trial 3: [A] = 0.250 M, [B] = 0.400 M, Rate = 14.50 M/min
What is the rate law for this reaction?

Accepted Answer

$$	ext{Rate} = k[A]^2[B]$$

Question 11

Which of the following is a requirement for a valid reaction mechanism?

Accepted Answer

The sum of the elementary steps must give the overall balanced equation.

Question 12

The rate constant for a reaction increases from $$1.1 \ \mathrm{L\ $$mol^{-1}$$\ s$$^{-1}$$} at$$ $$550^\circC to$$ $$6.4 \ \mathrm{L\ $$mol^{-1}$$\ s$$^{-1}$$} at$$ $$625^\circC. $$Which equation would you use to calculate the activation energy $$E_a$$?

Accepted Answer

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

Question 13

Which of the following best describes the collision model for chemical reactions?

Accepted Answer

Reactants must collide with sufficient energy and proper orientation to react.

Question 14

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

Accepted Answer

$$\ln\left(\frac{[A]_t}{[A]_0}\right) = -kt$$

Question 15

Which of the following is true for the half-life of a second-order reaction?

Accepted Answer

$$t_{1/2} = \frac{1}{k[A]_0}$$

Question 16

Which of the following is NOT a correct statement about reaction mechanisms?

Accepted Answer

A valid mechanism is always the actual mechanism.

Question 17

If a reaction is zero order in [A], what happens to the rate if [A] is doubled?

Accepted Answer

The rate remains unchanged.

Question 18

Which of the following is the correct expression for the Arrhenius equation?

Accepted Answer

$$k = Ae$$^{-E_a/RT}$$

Chemical Kinetics and Rate Laws: Structured Study Notes

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