Q: Which of the following is the correct expression for the average rate of disappearance of reactant A over a time interval $$\Delta t$$?

$$\displaystyle \text{Average rate} = -\frac{\Delta [A]}{\Delta t}$$

Q: For the reaction $$2\text{NO}_2(g) \rightarrow 2\text{NO}(g) + \text{O}_2(g)$$, which of the following correctly relates the rate of disappearance of $$\text{NO}_2 to $$the rate of appearance of $$\text{O}_2$$?

$$\displaystyle \text{Rate} = -\frac{1}{2} \frac{d[\text{NO}_2]}{dt} = \frac{d[\text{O}_2]}{dt}$$

Q: For the reaction $$2\text{NO}_2(g) \rightarrow 2\text{NO}(g) + \text{O}_2(g)$$, if the rate of disappearance of $$\text{NO}_2 is$$ $$0.10\ \text{mol/L} \cdot \text{s}$$, what is the rate of appearance of $$\text{O}_2$$?

$$0.05\ \text{mol/L} \cdot \text{s}$$

Question 1

Which of the following best describes the main focus of chemical kinetics?

Accepted Answer

The study of the speed or rate at which chemical reactions occur.

Question 2

Which factor would most likely increase the rate of a reaction where a solid reactant is involved?

Accepted Answer

Increasing the surface area of the solid reactant.

Question 3

A reaction is carried out at two different temperatures. At the higher temperature, the reaction proceeds much faster. Which statement best explains this observation?

Accepted Answer

The reactant molecules have more kinetic energy, leading to more frequent and energetic collisions.

Question 4

Which of the following is the correct expression for the average rate of disappearance of reactant A over a time interval $$\Delta t$$?

Accepted Answer

$$\displaystyle 	ext{Average rate} = -\frac{\Delta [A]}{\Delta t}$$

Question 5

For the reaction $$2	ext{NO}_2(g) ightarrow 2	ext{NO}(g) + 	ext{O}_2(g)$$, which of the following correctly relates the rate of disappearance of $$	ext{NO}_2 to $$the rate of appearance of $$	ext{O}_2$$?

Accepted Answer

$$\displaystyle 	ext{Rate} = -\frac{1}{2} \frac{d[	ext{NO}_2]}{dt} = \frac{d[	ext{O}_2]}{dt}$$

Question 6

Why does the rate of a chemical reaction generally decrease as the reaction proceeds?

Accepted Answer

The concentration of reactants decreases, leading to fewer effective collisions.

Question 7

Which of the following is a correct method for measuring the rate of a reaction in the laboratory?

Accepted Answer

Monitoring the change in concentration of a reactant or product over time using UV-Vis spectroscopy.

Question 8

For the reaction $$	ext{A} + 2	ext{B} ightarrow 3	ext{C}$$, the rate law is found to be $$	ext{rate} = k[	ext{A}][	ext{B}]^2. $$What is the overall order of the reaction?

Accepted Answer

Third order

Question 9

If doubling the concentration of reactant X causes the rate of a reaction to quadruple, what is the order of the reaction with respect to X?

Accepted Answer

Second order

Question 10

A catalyst increases the rate of a chemical reaction by:

Accepted Answer

Decreasing the activation energy required for the reaction.

Question 11

For the reaction $$2	ext{NO}_2(g) ightarrow 2	ext{NO}(g) + 	ext{O}_2(g)$$, if the rate of disappearance of $$	ext{NO}_2 is$$ $$0.10\ 	ext{mol/L} \cdot 	ext{s}$$, what is the rate of appearance of $$	ext{O}_2$$?

Accepted Answer

$$0.05\ 	ext{mol/L} \cdot 	ext{s}$$

Question 12

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

Accepted Answer

The rate at a specific moment, given by the slope of the tangent to the concentration vs. time curve.

Question 13

In a reaction, the rate law is determined to be $$	ext{rate} = k[	ext{A}]^0[	ext{B}]^1. $$What will happen to the rate if the concentration of A is doubled and B is kept constant?

Accepted Answer

The rate will remain unchanged.

Question 14

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

Accepted Answer

Molar mass of the products

Question 15

A student is investigating the decomposition of hydrogen peroxide, $$2	ext{H}_2	ext{O}_2(aq) ightarrow 2	ext{H}_2	ext{O}(l) + 	ext{O}_2(g). $$Which method would be most appropriate to monitor the rate of this reaction in the lab?

Accepted Answer

Measuring the volume of $$	ext{O}_2$$ gas produced over time.

Question 16

For the reaction $$aA + bB ightarrow cC + dD$$, the general rate law is given by $$	ext{rate} = k[A]^m[B]^n. $$What do the exponents m and n represent?

Accepted Answer

The experimentally determined orders of the reaction with respect to A and B.

Question 17

In a real-world scenario, why might a pharmaceutical company be interested in studying the kinetics of a drug degradation reaction?

Accepted Answer

To predict the shelf life and ensure the drug remains effective over time.

Question 18

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

Accepted Answer

It is determined experimentally and is specific for a given reaction at a given temperature.

Question 19

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

Accepted Answer

18

Chapter 14: Chemical Kinetics – Study Notes

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