Q: Given the concentration vs. time graph for the blue dye reaction, what is the initial rate of reaction if the concentration decreases from $3.40 \times 10^{-6}$ M to $2.00 \times 10^{-6}$ M in 1 minute?

$1.40 \times 10^{-6}$ mol/L\cdot min$

Q: Which equation correctly represents the average rate of disappearance of a reactant?

$\text{Rate} = -\frac{\Delta [\text{Reactant}]}{\Delta t}$

Q: For a reaction with a rate law $\text{Rate} = k[A]^2$, what are the units of the rate constant $k$ if concentration is in mol/L and time in seconds?

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

Question 1

Which of the following best describes the rate of a chemical reaction as shown in the blue dye and bleach experiment (see image)?

Accepted Answer

The rate is measured by the change in dye concentration over time.

Question 2

Given the concentration vs. time graph for the blue dye reaction, what is the initial rate of reaction if the concentration decreases from $3.40 	imes 10^{-6}$ M to $2.00 	imes 10^{-6}$ M in 1 minute?

Accepted Answer

$1.40 	imes 10^{-6}$ mol/L\cdot min$

Question 3

Which equation correctly represents the average rate of disappearance of a reactant?

Accepted Answer

$	ext{Rate} = -\frac{\Delta [	ext{Reactant}]}{\Delta t}$

Question 4

In a reaction where the concentration of a reactant decreases exponentially with time, which order of reaction is most likely?

Accepted Answer

First order

Question 5

Which plot would yield a straight line for a first-order reaction?

Accepted Answer

$\ln[R]$ vs. time

Question 6

For a second-order reaction, which integrated rate law equation is correct?

Accepted Answer

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

Question 7

If a reaction is zero order, what is the correct relationship between concentration and time?

Accepted Answer

$[R]_t = -kt + [R]_0$

Question 8

Which of the following statements about reaction rates is correct?

Accepted Answer

Reaction rates are always positive and depend on the stoichiometric coefficients.

Question 9

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

Accepted Answer

Third order

Question 10

For a first-order reaction, what is the formula for the half-life ($t_{1/2}$)?

Accepted Answer

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

Question 11

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

Accepted Answer

It increases the average energy per collision, leading to more effective collisions.

Question 12

In the reaction coordinate diagram, what does the peak represent?

Accepted Answer

The transition state or activated complex

Question 13

Which equation describes the Arrhenius relationship between rate constant and temperature?

Accepted Answer

$k = Ae^{\frac{-E_a}{RT}}$

Question 14

If a catalyst is added to a reaction, what happens to the activation energy and the equilibrium constant?

Accepted Answer

Activation energy decreases, equilibrium constant remains unchanged.

Question 15

Which plot would be linear for a second-order reaction?

Accepted Answer

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

Question 16

In a real-world scenario, why does a chilled piece of zinc react more slowly with HCl than a room-temperature piece?

Accepted Answer

The chilled zinc has collisions with lower energy, so fewer are effective.

Question 17

Which of the following is NOT a factor that affects reaction rate?

Accepted Answer

Color of the reactants

Question 18

For a reaction with a rate law $	ext{Rate} = k[A]^2$, what are the units of the rate constant $k$ if concentration is in mol/L and time in seconds?

Accepted Answer

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

Question 19

Which statement about the rate law for an elementary step is correct?

Accepted Answer

The order of each reactant equals its stoichiometric coefficient in the elementary step.

Chemical Kinetics and Equilibrium: Study Notes for General Chemistry

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