Question 1

Which of the following best describes dynamic equilibrium in a chemical reaction?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 2

Hemoglobin binds to oxygen in the lungs and releases it in the muscles. Which statement best explains this behavior using equilibrium concepts?

Accepted Answer

High $$[O_2$] in $$the lungs shifts the equilibrium to the right, forming more HbO$$_2.$$

Question 3

For the reaction $$2A + B \rightleftharpoons 3C$$, what is the correct equilibrium constant expression according to the law of mass action?

Accepted Answer

$$K = \frac{[C]^3}{[A]^2[B]}$$

Question 4

A reaction mixture initially contains $$[A] = 1.1 M $$and $$[B] = 0.0 M $$for the reaction $$A \rightleftharpoons B$$ with $$K = 10. $$Which statement is true at equilibrium?

Accepted Answer

The reaction mixture contains $$[A] = 0.1 M $$and $$[B] = 1.0 M.$$

Question 5

Which of the following statements about the equilibrium constant $$K is $$correct?

Accepted Answer

A large $$K$$ value means the reaction favors products at equilibrium.

Question 6

For the reaction $$2N_2O_5(g) \rightleftharpoons 4NO_2(g) + O_2$(g)$$, what is the correct equilibrium constant expression?

Accepted Answer

$$K = \frac{[NO_2$]^4[O_2$]}{[N_2O_5]^2}$$

Question 7

Which of the following is true about the concentrations of reactants and products at equilibrium?

Accepted Answer

They remain constant over time.

Question 8

For the reaction $$aA(g) + bB(g) \rightleftharpoons cC(g) + dD(g)$$, under what condition are $$K_p$$ and $$K_c$$ equal?

Accepted Answer

If $$a + b = c + d$$

Question 9

Which of the following is NOT included in the equilibrium constant expression for a heterogeneous equilibrium?

Accepted Answer

Pure solids

Question 10

Consider the reaction $$2CO(g) \rightleftharpoons CO_2$(g) + C(s). If $$the amount of solid carbon is doubled, what happens to the equilibrium concentrations of $$CO$$ and $$CO_2$$?

Accepted Answer

Neither $$[CO]$$ nor $$[CO_2$]$$ change.

Question 11

Which of the following best explains why $$K is $$unitless, even though concentrations and pressures have units?

Accepted Answer

Because concentrations and pressures are divided by their standard values before being used in the $$K$$ expression.

Question 12

For the reaction $$A(g) \rightleftharpoons B(g)$$, three equilibrium mixtures are observed at different temperatures. At which temperature is the equilibrium constant $$K$$ the largest?

Accepted Answer

At the temperature where the concentration of B is highest.

Question 13

Which of the following is a correct relationship between $$K_p$$ and $$K_c$$ for the reaction $$aA(g) + bB(g) \rightleftharpoons cC(g) + dD(g)$$?

Accepted Answer

$$K_p = K_c(RT$$)^{\Delta n}$$, where $$\Delta n = (c + d) - (a + b)$$

Question 14

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

Accepted Answer

Adding more product to the system.

Question 15

Which of the following is a real-life application of chemical equilibrium?

Accepted Answer

Oxygen transport by hemoglobin in the blood.

Chemical Equilibrium: Principles, Expressions, and Applications

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