Q: Which of the following is true about the relationship between $$K_c$$ and $$K_p$$?

$$K_p = K_c \times (RT$$)^{\Delta n}$$, where $$\Delta n$$ is the difference in moles of gaseous products and reactants.

Q: For the reaction $$SO_2Cl_2(g) \rightleftharpoons SO_2$(g) + Cl_2$(g)$$, if the initial concentration of $$SO_2Cl_2 is 0.020 M $$and at equilibrium $$[Cl_2$] = 1.2 \times 10$$^{-2}$$ M, what is the value of the equilibrium constant K_c$?

$$K_c = 1.2 \times 10$$^{-2}$$ \times 1.2 \times 10$$^{-2}$$ / (0.020 - 1.2 \times 10$$^{-2}$$)$$

Question 1

For the reaction $$2 \mathrm{N_2O_5}(g) \rightarrow 4 \mathrm{NO_2$}(g) + \mathrm{O_2$}(g)$$, which of the following is the correct equilibrium constant expression?

Accepted Answer

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

Question 2

Which statement best describes the law of mass action for a general reaction $$aA + bB \rightarrow cC + dD$$?

Accepted Answer

The equilibrium constant is the ratio of the concentrations of products raised to their coefficients over the concentrations of reactants raised to their coefficients.

Question 3

For the reaction $$CO(g) + 2 H_2$(g) \rightarrow CH_3OH(g)$$, what is the equilibrium constant expression $$K$$?

Accepted Answer

$$K = \frac{[CH_3OH]}{[CO][H_2$]^2}$$

Question 4

If the reaction $$2 NO_2$(g) \rightleftharpoons N_2O_4(g)$$ has an equilibrium constant $$K = 0.125$$ and the initial pressure of $$NO_2 is 1.66 $$atm, what is the equilibrium partial pressure of $$N_2O_4$$?

Accepted Answer

0.199 atm

Question 5

Which of the following changes will shift the equilibrium of $$H_2(g$$) + $$I_2(g$$) \rightleftharpoons 2 HI(g)$$ to the right?

Accepted Answer

Adding $$H_2$$

Question 6

For the reaction $$N_2(g) + 3$$ $$H_2(g$$) \rightleftharpoons 2 $$NH_3(g$$)$$, what happens to the equilibrium if the volume of the container is decreased?

Accepted Answer

The equilibrium shifts to the side with fewer moles of gas, favoring $$NH_3$$ formation.

Question 7

Given $$K_c$$ for a reaction at 25°C is $$3.5 	imes 10^5$, calculate K_p$ for 3$$ $$H_2(g$$) + $$N_2(g$$) ightleftharpoons 2 $$NH_3(g$$)$$ at 25°C. (R = 0.0821$ L·atm·mol$$^{-1}$$·K$$^{-1}$$, T = 298$ K)

Accepted Answer

$$K_p = 5.8 	imes 10^3$

Question 8

Which of the following is true about the relationship between $$K_c$$ and $$K_p$$?

Accepted Answer

$$K_p = K_c 	imes (RT$$)^{\Delta n}$$, where $$\Delta n$$ is the difference in moles of gaseous products and reactants.

Question 9

For the reaction $$SO_2Cl_2(g) ightleftharpoons SO_2$(g) + Cl_2$(g)$$, if the initial concentration of $$SO_2Cl_2 is 0.020 M $$and at equilibrium $$[Cl_2$] = 1.2 	imes 10$$^{-2}$$ M, what is the value of the equilibrium constant K_c$?

Accepted Answer

$$K_c = 1.2 	imes 10$$^{-2}$$ 	imes 1.2 	imes 10$$^{-2}$$ / (0.020 - 1.2 	imes 10$$^{-2}$$)$$

Question 10

A reaction mixture contains only products. What is the value of the reaction quotient $$Q$$ and in which direction will the reaction proceed?

Accepted Answer

$$Q = 0$$, reaction proceeds in the reverse direction.

Question 11

For the reaction $$2 NO_2$(g) \rightleftharpoons N_2O_4(g)$$, if $$K = 0.125$$ and the initial pressure of $$NO_2 is 1.66 $$atm, what is the quadratic equation used to solve for $$x ($$the change in pressure)?

Accepted Answer

$$0.125 = \frac{x}{(1.66 - 2x)^2$}$$

Question 12

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

Accepted Answer

Pure solids and pure liquids

Question 13

If the reaction $$CaCO_3(s$$) \rightleftharpoons CaO(s) + $$CO_2(g$$)$$ is exothermic, what is the effect of increasing the temperature?

Accepted Answer

The equilibrium shifts to the left, favoring $$CaCO_3$$ formation.

Question 14

For the reaction $$2 NO(g) + O_2$(g) \rightleftharpoons 2 NO_2$(g)$$, $$K_p = 6.47 at 298 K. If a $$container initially contains 0.055 mol of $$NO$$ and 0.021 mol of $$O_2$$, in which direction will the reaction proceed?

Accepted Answer

Forward, toward $$NO_2$$ formation

Question 15

Which of the following best describes the effect of adding an inert gas at constant volume to a reaction at equilibrium?

Accepted Answer

No effect on the position of equilibrium

Question 16

For the reaction $$A(g) + B(g) ightleftharpoons 2 C(g)$$, if $$K_c = 1.0 	imes 10^2$ and K_p = 1.0$$ 	imes $$10^1 at 298 K$$, what is the value of $$\Delta n$$?

Accepted Answer

$$\Delta n = 1$$

Question 17

Which of the following is the correct equilibrium constant expression for the reaction $$Fe^{3+}(aq) + $$SCN^-(aq) \rightleftharpoons $$FeSCN^{2+}(aq$$)$$?

Accepted Answer

$$K = \frac{[$$FeSCN^{2+}$$]}{[Fe$$^{3+}$$][SCN^-]}$$

Chemical Equilibrium: Equilibrium Constants, ICE Tables, and Le Chatelier’s Principle

Study Guide - Practice Questions

Study Guide - Flashcards