Q: For the reaction $2A + B \rightarrow 3C + D$, which of the following correctly expresses the rate in terms of the change in concentration of each species?

$\text{Rate} = -\frac{1}{2} \frac{d[A]}{dt} = -\frac{d[B]}{dt} = \frac{1}{3} \frac{d[C]}{dt} = \frac{d[D]}{dt}$

Question 1

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

Accepted Answer

The change in concentration of a reactant or product per unit time.

Question 2

For the reaction $2A + B \rightarrow 3C + D$, which of the following correctly expresses the rate in terms of the change in concentration of each species?

Accepted Answer

$	ext{Rate} = -\frac{1}{2} \frac{d[A]}{dt} = -\frac{d[B]}{dt} = \frac{1}{3} \frac{d[C]}{dt} = \frac{d[D]}{dt}$

Question 3

Which of the following is NOT a common experimental technique for measuring the rate of a chemical reaction?

Accepted Answer

Measuring the change in temperature (thermometry)

Question 4

What is the difference between the average rate and the instantaneous rate of a reaction?

Accepted Answer

The average rate is measured over a time interval, while the instantaneous rate is measured at a specific moment.

Question 5

Which of the following best defines a rate law for a chemical reaction?

Accepted Answer

An equation that relates the rate of a reaction to the concentration of reactants, each raised to a power.

Question 6

For a reaction that is first order in reactant A, which of the following is the correct rate law?

Accepted Answer

$	ext{Rate} = k[A]$

Question 7

Which statement about zero-order reactions is correct?

Accepted Answer

The rate of the reaction is independent of the concentration of the reactant.

Question 8

A student is studying the reaction $A \rightarrow B$ and finds that doubling the concentration of A quadruples the rate. What is the order of the reaction with respect to A?

Accepted Answer

Second order

Question 9

Which of the following is the integrated rate law for a first-order reaction $A \rightarrow$ products?

Accepted Answer

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

Question 10

Which method is commonly used to determine the order of a reaction experimentally?

Accepted Answer

The Method of Initial Rates

Question 11

For a reaction that is second order in A, what is the correct integrated rate law?

Accepted Answer

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

Question 12

A reaction is found to be zero order in A. If the initial concentration of A is $0.50$ M and the rate constant $k = 0.10$ M/s, how long will it take for the concentration of A to decrease to $0.20$ M?

Accepted Answer

$3.0$ s

Question 13

Which of the following statements about the integrated rate law is correct?

Accepted Answer

It relates the concentration of a reactant to time for a given reaction order.

Question 14

In a real-world scenario, the decomposition of hydrogen peroxide ($2H_2O_2 \rightarrow 2H_2O + O_2$) is monitored by measuring the volume of oxygen gas produced over time. Which experimental method is being used to measure the reaction rate?

Accepted Answer

Measuring the change in pressure or volume of a gas

Question 15

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

Accepted Answer

Third order

Question 16

A chemist observes that the rate of a reaction does not change when the concentration of reactant A is doubled. What is the most likely order of the reaction with respect to A?

Accepted Answer

Zero order

Question 17

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

Accepted Answer

Measuring the initial rate of reaction at different initial concentrations to determine the reaction order.

Question 18

For a first-order reaction, what is the half-life ($t_{1/2}$) expression in terms of the rate constant $k$?

Accepted Answer

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

Question 19

A reaction is first order in A. If $[A]_0 = 0.80$ M, $k = 0.25$ s$^{-1}$, what is $[A]$ after $4.0$ s? (Use $[A] = [A]_0 e^{-kt}$)

Accepted Answer

$0.16$ M

General Chemistry Study Guide: Reaction Rates and Rate Laws

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