Question 1

Which part of the Arrhenius equation $$k = Ae$$^{-\frac{E_a}$${RT}} is $$directly responsible for the temperature dependence of the rate constant?

Accepted Answer

The exponential factor $$e^{-\frac{E_a}$${RT}}$$

Question 2

According to collision theory, which of the following is NOT a requirement for a successful chemical reaction between two molecules?

Accepted Answer

The molecules must be in the gas phase.

Question 3

A reaction has a high activation energy ($$E_a). $$What can you infer about its rate at room temperature?

Accepted Answer

The reaction will proceed very slowly.

Question 4

Which of the following best describes the transition state in a chemical reaction?

Accepted Answer

A high-energy, unstable arrangement of atoms between reactants and products.

Question 5

For the reaction $$2	ext{NO}_2(g) ightarrow 2	ext{NO}(g) + 	ext{O}_2(g)$$, which of the following collisions will most likely lead to a reaction?

Accepted Answer

A collision where the NO$$_2$$ molecules have sufficient energy and the correct orientation.

Question 6

If the rate constant $$k$$ for a reaction increases when the temperature is raised, what is the most likely explanation?

Accepted Answer

The exponential factor $$e^{-\frac{E_a}$${RT}}$$ increases as T$ increases.

Question 7

A reaction has a frequency factor $$A of$$ $$1.0 	imes 10$$^{12}$$ 	ext{ s}^{-1}$$ and an activation energy $$E_a of$$ $$80 	ext{ kJ mol}^{-1}. If $$the temperature increases, what happens to the exponential factor and the rate constant?

Accepted Answer

Both the exponential factor and the rate constant increase.

Question 8

Which of the following statements about catalysts is TRUE?

Accepted Answer

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

Question 9

In a potential energy diagram for a reaction, what does the height of the energy barrier between reactants and products represent?

Accepted Answer

The activation energy ($$E_a) of $$the reaction.

Question 10

A certain reaction has a forward activation energy of $$60 	ext{ kJ mol}^{-1}$$ and a reverse activation energy of $$140 	ext{ kJ mol}^{-1}. $$What is the enthalpy change ($$\Delta H) $$for the reaction?

Accepted Answer

$$-80 	ext{ kJ mol}^{-1}$$

Question 11

Which of the following best explains why not all molecular collisions result in a chemical reaction?

Accepted Answer

Most collisions do not have enough energy or the correct orientation.

Question 12

If two reactions have identical frequency factors but different activation energies, which reaction will have the higher rate constant at the same temperature?

Accepted Answer

The reaction with the lower activation energy.

Question 13

A catalyst is added to a reaction at equilibrium. What effect does this have on the position of equilibrium and the rate at which equilibrium is reached?

Accepted Answer

It does not change the position of equilibrium but increases the rate at which equilibrium is reached.

Question 14

Which of the following is a correct statement about the frequency factor ($$A) in $$the Arrhenius equation?

Accepted Answer

It represents the total number of collision attempts per unit time.

Question 15

In the context of collision theory, what is the 'orientation factor'?

Accepted Answer

The fraction of collisions with the correct spatial alignment to react.

Question 16

A reaction is found to proceed much faster in the presence of a platinum surface. What type of catalysis is this an example of?

Accepted Answer

Heterogeneous catalysis

Question 17

Which of the following changes will increase the rate constant $$k$$ for a reaction, according to the Arrhenius equation?

Accepted Answer

Increasing the temperature

Question 18

In a real-world scenario, why does a car's catalytic converter use metals like platinum and palladium?

Accepted Answer

They provide a surface for heterogeneous catalysis, speeding up the conversion of harmful gases.

Question 19

Which of the following best describes the effect of increasing temperature on the fraction of molecules with enough energy to react?

Accepted Answer

The fraction increases.

Question 20

Which of the following statements about the transition state (activated complex) is correct?

Accepted Answer

It is a high-energy, short-lived state that exists at the peak of the energy barrier.

Chemical Kinetics: Temperature, Reaction Mechanisms, and Catalysis

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