Question 1

Which of the following best describes the dynamic equilibrium shown in the first image (ice cubes in water at 0°C)?

Accepted Answer

The rate of melting equals the rate of freezing.

Question 2

For the reaction $$2\ \mathrm{O}_3\ (g)\ ightleftharpoons\ 3\ \mathrm{O}_2\ (g)$$, the equilibrium constant $$K_c is$$ $$4.38 	imes 10$$^{28}$$. What does this value indicate about the composition of the equilibrium mixture?

Accepted Answer

The mixture contains mostly oxygen ($$\mathrm{O}_2).$$

Question 3

Which statement about equilibrium constants is correct?

Accepted Answer

If $$K_c \u003e 1$$, products are favored at equilibrium.

Question 4

Consider the reaction $$2\ \mathrm{NO}\ (g) + \mathrm{Cl}_2\ (g) \rightleftharpoons 2\ \mathrm{NOCl}\ (g) at 700 K$$, where $$K_p = 0.26. If$$ $$\Delta n = 0$$, what is the relationship between $$K_p$$ and $$K_c$$?

Accepted Answer

$$K_p = K_c$$

Question 5

Which of the following is NOT a correct way to manipulate equilibrium constants?

Accepted Answer

Multiplying a reaction by $$n$$ divides the equilibrium constant by $$n.$$

Question 6

In a heterogeneous equilibrium involving a solid and a gas, such as $$\mathrm{Ni}\ (s) + 4\ \mathrm{CO}\ (g) \rightleftharpoons \mathrm{Ni(CO)}_4\ (g)$$, how is the concentration of the solid treated in the equilibrium expression?

Accepted Answer

It is ignored because it is constant.

Question 7

For the reaction $$3\ \mathrm{H}_2\ (g) + \mathrm{N}_2\ (g) \rightleftharpoons 2\ \mathrm{NH}_3\ (g)$$, which of the following is the correct equilibrium expression?

Accepted Answer

$$K_c = \dfrac{[\mathrm{NH}_3]^2}{[\mathrm{H}_2]^3[\mathrm{N}_2]}$$

Question 8

If the equilibrium constant for $$\mathrm{N}_2\mathrm{O}_4\ (g) \rightleftharpoons 2\ \mathrm{NO}_2\ (g) is$$ $$K_{c1}$$, what is the equilibrium constant for $$2\ \mathrm{N}_2\mathrm{O}_4\ (g) \rightleftharpoons 4\ \mathrm{NO}_2\ (g)$$?

Accepted Answer

$$K_{c1}^2$$

Question 9

A saturated solution is an example of which type of equilibrium?

Accepted Answer

Physical equilibrium

Question 10

If two reactions are added together, how is the equilibrium constant for the overall reaction determined?

Accepted Answer

By multiplying the equilibrium constants

Question 11

Which of the following best explains why $$K_p is $$usually not equal to $$K_c$$ for gas-phase reactions?

Accepted Answer

Because $$K_p$$ uses partial pressures and $$K_c$$ uses concentrations, and the change in moles of gas ($$\Delta n) $$affects their relationship.

Question 12

In the context of chemical equilibrium, what does a double-sided arrow ($$\rightleftharpoons) $$indicate?

Accepted Answer

The reaction can proceed in both forward and reverse directions.

Question 13

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

Accepted Answer

They remain constant over time.

Question 14

If the equilibrium constant for a reaction is very small ($$K_c \ll 1$$), what does this imply about the equilibrium mixture?

Accepted Answer

The mixture contains mostly reactants.

Question 15

For the reaction $$2\ \mathrm{N}_2\mathrm{O}_5\ (g) \rightleftharpoons 4\ \mathrm{NO}_2\ (g) + \mathrm{O}_2\ (g)$$, which of the following is the correct equilibrium expression?

Accepted Answer

$$K_c = \dfrac{[\mathrm{NO}_2]^4[\mathrm{O}_2]}{[\mathrm{N}_2\mathrm{O}_5]^2}$$

Question 16

Which of the following best describes the effect of manipulating a reaction on its equilibrium constant?

Accepted Answer

Multiplying a reaction by $$n$$ raises the equilibrium constant to the $$nth $$power.

Question 17

Which of the following is ignored when writing the equilibrium expression for a heterogeneous equilibrium?

Accepted Answer

Concentration of solids

Question 18

A student mixes ice and water in a beaker at 0°C and 1 atm. Which statement best describes the system after a long time?

Accepted Answer

The amount of ice and water will remain constant as melting and freezing occur at equal rates.

Question 19

Which of the following is a real-life example of a physical equilibrium?

Accepted Answer

The melting and freezing of ice in water at 0°C.

Chemical Equilibrium: Principles, Constants, and Applications

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