Q: The decomposition of hydrogen peroxide is first order with $$k = 1.06 \times 10$$^{-3}$$\ \mathrm{min}^{-1}. $$What is the half-life?

$$\frac{0.693}{1.06 \times 10$$^{-3}$$} = 654\ \mathrm{min}$$

Question 1

Refer to the phase diagram of carbon. At approximately what pressure and temperature does diamond become the stable phase of carbon?

Accepted Answer

At high pressure and low temperature

Question 2

Which of the following best describes the units of a reaction rate?

Accepted Answer

$$\mathrm{mol\cdot L$$^{-1}$$\cdot s$$^{-1}$$}$$

Question 3

For the reaction $$2\mathrm{NO_2$} \rightarrow 2\mathrm{NO} + \mathrm{O_2$}$$, if $$\mathrm{NO_2$} is $$disappearing at a rate of $$0.10\ \mathrm{M/s}$$, at what rate is $$\mathrm{O_2$}$$ appearing?

Accepted Answer

$$0.05\ \mathrm{M/s}$$

Question 4

Which of the following is true about the rate law for a reaction?

Accepted Answer

It must be determined experimentally.

Question 5

Given the rate law $$\mathrm{Rate} = k[\mathrm{A}]^2[\mathrm{B}]$$, what is the overall order of the reaction?

Accepted Answer

Third order

Question 6

A reaction has the following data: doubling $$[\mathrm{A}]$$ doubles the rate, doubling $$[\mathrm{B}]$$ quadruples the rate. What is the rate law?

Accepted Answer

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

Question 7

Which integrated rate law corresponds to a first-order reaction?

Accepted Answer

$$\ln [A]_t = \ln [A]_0 - kt$$

Question 8

A plot of $$\ln [A]$$ versus time yields a straight line with a negative slope. What is the order of the reaction?

Accepted Answer

First order

Question 9

For a second-order reaction, which plot yields a straight line?

Accepted Answer

$$\frac{1}{[A]} vs. $$time

Question 10

The decomposition of hydrogen peroxide is first order with $$k = 1.06 	imes 10$$^{-3}$$\ \mathrm{min}^{-1}. $$What is the half-life?

Accepted Answer

$$\frac{0.693}{1.06 	imes 10$$^{-3}$$} = 654\ \mathrm{min}$$

Question 11

Which of the following is true for a zero-order reaction?

Accepted Answer

The rate is independent of reactant concentration.

Question 12

If the rate law for a reaction is $$\mathrm{Rate} = k[\mathrm{A}]$$, what are the units of $$k$$?

Accepted Answer

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

Question 13

A reaction is found to be zero order in $$\mathrm{A}. If$$ $$[\mathrm{A}] is $$doubled, what happens to the rate?

Accepted Answer

It remains the same

Question 14

Which of the following best describes the method of initial rates?

Accepted Answer

It measures the rate at the very beginning, before products accumulate.

Question 15

A reaction has the rate law $$\mathrm{Rate} = k[\mathrm{A}][\mathrm{B}]. If$$ $$[\mathrm{A}] is $$tripled and $$[\mathrm{B}] is $$doubled, by what factor does the rate increase?

Accepted Answer

6

Question 16

Which of the following is a real-life example of a first-order reaction?

Accepted Answer

Radioactive decay

Question 17

If a plot of $$[A] vs. $$time is linear with a negative slope, what is the order of the reaction?

Accepted Answer

Zero order

Question 18

For the reaction $$\mathrm{N_2$} + 3\mathrm{H_2$} \rightarrow 2\mathrm{NH_3$}$$, if $$\mathrm{NH_3$} is $$forming at $$0.024\ \mathrm{M/s}$$, at what rate is $$\mathrm{H_2$}$$ disappearing?

Accepted Answer

$$0.036\ \mathrm{M/s}$$

Question 19

Which of the following statements about the rate constant $$k is $$correct?

Accepted Answer

It depends on the reaction and temperature.

Question 20

A reaction is second order with respect to $$\mathrm{HI}$$, with $$k = 30\ \mathrm{L\cdot $$mol^{-1}$$\cdot s$$^{-1}$$} at$$ $$443^\circC. $$How much time is required for $$[\mathrm{HI}] to $$decrease from $$0.010\ \mathrm{M} to$$ $$0.0050\ \mathrm{M}$$?

Accepted Answer

$$\frac{1}{k} \left( \frac{1}{[HI]_t} - \frac{1}{[HI]_0} \right ) = \frac{1}{30} (200 - 100) = 3.3\ \mathrm{s}$$

Chemical Kinetics: Reaction Rates and Rate Laws

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