Q: Which of the following best describes the reaction rate for the hypothetical reaction $$aA + bB \rightarrow cC + dD$$?

$$\text{Rate} = -\frac{1}{a} \frac{\Delta [A]}{\Delta t} = -\frac{1}{b} \frac{\Delta [B]}{\Delta t} = \frac{1}{c} \frac{\Delta [C]}{\Delta t} = \frac{1}{d} \frac{\Delta [D]}{\Delta t}$$

Q: A reaction is found to be second order in $$[NO]$$ and first order in $$[H_2$]. $$What is the rate law for this reaction?

$$\text{Rate} = k[NO]^2[H_2$]$$

Question 1

Which of the following best describes the reaction rate for the hypothetical reaction $$aA + bB \rightarrow cC + dD$$?

Accepted Answer

$$	ext{Rate} = -\frac{1}{a} \frac{\Delta [A]}{\Delta t} = -\frac{1}{b} \frac{\Delta [B]}{\Delta t} = \frac{1}{c} \frac{\Delta [C]}{\Delta t} = \frac{1}{d} \frac{\Delta [D]}{\Delta t}$$

Question 2

A reaction is found to be second order in $$[NO]$$ and first order in $$[H_2$]. $$What is the rate law for this reaction?

Accepted Answer

$$	ext{Rate} = k[NO]^2[H_2$]$$

Question 3

Which of the following statements about catalysts is TRUE?

Accepted Answer

A catalyst provides an alternative pathway with a lower activation energy.

Question 4

For a first-order reaction, which of the following plots will yield a straight line?

Accepted Answer

$$\ln[A] vs$$ $$t$$

Question 5

The decomposition of hydrogen iodide, $$2HI(g) ightarrow H_2$(g) + I_2$(g)$$, has rate constants of $$9.51 	imes 10$$^{-3}$$ \ L/(mol \cdot s) at$$ $$500\ K$$ and $$1.10 	imes 10$$^{-2}$$ \ L/(mol \cdot s) at$$ $$600\ K. $$Which equation would you use to calculate the activation energy $$E_a$$?

Accepted Answer

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

Question 6

Which of the following factors does NOT affect the rate of a chemical reaction?

Accepted Answer

The overall enthalpy change ($$\Delta H) of $$the reaction

Question 7

For a zero-order reaction, what is the relationship between concentration and time?

Accepted Answer

$$[A] = [A]_0 - kt$$

Question 8

A reaction has a rate law $$	ext{Rate} = k[A][B]^2. If $$the concentration of $$B is $$doubled while $$A is $$kept constant, by what factor does the rate increase?

Accepted Answer

4

Question 9

Which of the following best describes the effect of temperature on the rate constant $$k$$ according to the Arrhenius equation?

Accepted Answer

$$k$$ increases exponentially as $$T$$ increases

Question 10

For a reaction mechanism, which step determines the overall rate law?

Accepted Answer

The slowest (rate-determining) step

Question 11

The half-life for a first-order reaction is given by which equation?

Accepted Answer

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

Question 12

Which of the following is TRUE about the collision theory of chemical reactions?

Accepted Answer

Only collisions with energy greater than the activation energy are effective.

Question 13

A reaction is zero order in $$[A]. If $$the initial concentration of $$A is$$ $$0.50\ M$$ and the rate constant $$k is$$ $$0.10\ M/s$$, how long will it take for $$[A] to $$reach zero?

Accepted Answer

$$5.0\ s$$

Question 14

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

Accepted Answer

The sum of the elementary steps must equal the overall reaction.

Question 15

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

Accepted Answer

A plot of $$1/[A] vs$$ $$t is $$linear.

Question 16

If the rate law for a reaction is $$	ext{Rate} = k[A]^0[B]^2$$, what is the overall order of the reaction?

Accepted Answer

Second order

Question 17

Which of the following statements about the effect of a catalyst on a reaction is correct?

Accepted Answer

A catalyst lowers the activation energy for both the forward and reverse reactions.

Question 18

The rate constant $$k$$ for a first-order reaction has which units?

Accepted Answer

$$s^{-1}$$

Question 19

Which of the following best explains why increasing the temperature increases the rate of a chemical reaction?

Accepted Answer

It increases the number of collisions with energy greater than the activation energy.

Chemical Kinetics: Principles, Rate Laws, and Mechanisms

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