Question 1

Which of the following best describes the state of chemical equilibrium in a closed system?

Accepted Answer

The forward and reverse reactions occur at the same rate.

Question 2

Consider the reaction $$\mathrm{N_2O_4 (g) \rightleftharpoons 2 NO_2$ (g)}. If $$the system is at equilibrium and more $$\mathrm{NO_2$} is $$added, what will happen to the concentration of $$\mathrm{N_2O_4}$$?

Accepted Answer

It will increase.

Question 3

Why does the rate of the forward reaction slow down as a reaction proceeds toward equilibrium?

Accepted Answer

Because the concentration of reactants is decreasing.

Question 4

A sealed tube contains a mixture of colorless $$\mathrm{N_2O_4}$$ and brown $$\mathrm{NO_2$}. If $$the tube is left overnight at constant temperature, what will happen to the color intensity of the brown $$\mathrm{NO_2$}$$?

Accepted Answer

It will remain the same.

Question 5

Which of the following statements is true at chemical equilibrium?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 6

In a real-world scenario, why is it important for the human body to maintain chemical equilibrium in blood gases such as $$\mathrm{CO_2$}$$ and $$\mathrm{O_2$}$$?

Accepted Answer

To maintain constant concentrations of gases for proper physiological function.

Question 7

Which of the following best explains why the concentrations of reactants and products remain constant at equilibrium?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 8

A student observes that the color of a reaction mixture does not change over time. Which of the following is the best conclusion?

Accepted Answer

The system has reached chemical equilibrium.

Question 9

For the reaction $$\mathrm{N_2O_4 (g) \rightleftharpoons 2 NO_2$ (g)}$$, which of the following would NOT affect the position of equilibrium?

Accepted Answer

Adding a catalyst.

Question 10

A chemical reaction is at equilibrium. Which of the following changes will disturb the equilibrium and cause the system to shift?

Accepted Answer

Increasing the concentration of a reactant.

Question 11

If the forward reaction in a system is exothermic, what will happen to the equilibrium position if the temperature is increased?

Accepted Answer

It will shift toward the reactants.

Question 12

Which of the following is a correct statement about dynamic equilibrium?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 13

A reaction vessel contains only products at the start. Over time, the concentration of products decreases and the concentration of reactants increases until both remain constant. What has occurred?

Accepted Answer

The system has reached equilibrium.

Question 14

In the context of chemical equilibrium, what does it mean for a system to be 'dynamic'?

Accepted Answer

Both the forward and reverse reactions continue to occur.

Question 15

Which of the following real-life scenarios best illustrates the concept of chemical equilibrium?

Accepted Answer

A sealed bottle of soda where the rate of $$\mathrm{CO_2$}$$ dissolving equals the rate of $$\mathrm{CO_2$}$$ escaping.

Chemical Equilibrium: Concepts and Examples

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