Question 1

Which statement best describes the role of a catalyst in a chemical reaction?

Accepted Answer

A catalyst provides an alternative reaction pathway with lower activation energy, increasing the reaction rate.

Question 2

Which of the following is true regarding enzymes?

Accepted Answer

Enzymes are biological catalysts that provide a pathway with lower activation energy.

Question 3

Consider the decomposition of ozone catalyzed by chlorine atoms. What effect does the catalyst have on the activation energy ($$E_a) $$and the rate constant ($$k$$)?

Accepted Answer

The catalyst decreases $$E_a$$ and increases $$k$$ exponentially.

Question 4

Which of the following best explains why a catalyst does not appear in the overall reaction equation?

Accepted Answer

It is used in one step and regenerated in a subsequent step, so its net change is zero.

Question 5

In a catalytic converter, which metals are commonly used to catalyze the conversion of CO and unburned hydrocarbons to less harmful products?

Accepted Answer

Platinum (Pt), rhodium (Rh), and palladium (Pd)

Question 6

Which process involves molecules adhering to a catalyst surface through weak intermolecular forces?

Accepted Answer

Physical adsorption

Question 7

Which equation correctly represents the first law of thermodynamics for a closed system?

Accepted Answer

$$\Delta U = q + w$$

Question 8

A bomb calorimeter is used to measure the heat of a reaction at constant volume. Which equation should be used to calculate the change in internal energy ($$\Delta U$$)?

Accepted Answer

$$\Delta U = q_v$$

Question 9

Which of the following statements about the universe as a thermodynamic system is correct?

Accepted Answer

The universe is an isolated system; the amount of matter and energy is conserved.

Question 10

During a chemical reaction, which of the following is generally true regarding bond breaking and bond making?

Accepted Answer

Bond breaking requires energy and bond making releases energy.

Question 11

Which of the following best describes chemisorption in heterogeneous catalysis?

Accepted Answer

Molecules adhere to the surface by strong chemical bonding.

Question 12

A reaction occurs in a coffee cup calorimeter at constant pressure. Which equation should be used to calculate the enthalpy change ($$\Delta H$$)?

Accepted Answer

$$\Delta H = \Delta U + p\Delta V$$

Question 13

Which of the following is NOT a characteristic of a catalyst?

Accepted Answer

It appears in the overall reaction equation as a product.

Question 14

In the context of thermodynamics, which of the following is an example of a closed system?

Accepted Answer

A sealed flask where only energy can be exchanged with the surroundings.

Question 15

Which of the following reactions is catalyzed in a car's catalytic converter to reduce air pollution?

Accepted Answer

$$2NO + 2NO_2 \rightarrow 2N_2 + 3O_2$$

Question 16

Which of the following best describes the difference between physical adsorption and chemisorption in catalysis?

Accepted Answer

Physical adsorption involves weak intermolecular forces, while chemisorption involves strong chemical bonds.

Question 17

If a reaction is performed in a bomb calorimeter and the volume does not change, what is the relationship between the heat measured ($$q_v) $$and the change in internal energy ($$\Delta U$$)?

Accepted Answer

$$\Delta U = q_v$$

Question 18

Which of the following is a correct statement about the measurement of internal energy ($$U) in $$thermodynamics?

Accepted Answer

We can only measure changes in $$U$$, not absolute values.

Question 19

Which of the following is a real-world example of a system in thermodynamics?

Accepted Answer

A reacting solution in a flask

Catalysis, Thermodynamics, and System Concepts in General Chemistry

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