Question 1

For the reaction $$\mathrm{A(g) \rightleftharpoons B(g)}$$, the equilibrium constant is $$K_1. $$What is the equilibrium constant for the reaction $$2\mathrm{A(g) \rightleftharpoons 2B(g)}$$?

Accepted Answer

$$K_1^2$

Question 2

Given the following reactions and their equilibrium constants:

$$\mathrm{FeO(s) + CO(g) ightleftharpoons Fe(s) + CO_2$(g)}$$, $$K_1 = 4.17$

$$\mathrm{2CO(g) + $$O_2(g$$) ightleftharpoons 2CO_2(g)}$$, K_2$ = 1.01 	imes 10$$^{15}$$

What is the equilibrium constant for the reaction 2$$\mathrm{Fe(s)} + $$O_2(g$$) ightleftharpoons 2\mathrm{FeO(s)}$$?

Accepted Answer

$$K = \dfrac{K_2$}{K_1$^2}$$

Question 3

For the general reaction $$aA + bB \rightleftharpoons cC + dD$$, the reaction quotient $$Q is $$given by:

Accepted Answer

$$Q = \dfrac{[C]^c[D]^d}{[A]^a[B]^b}$$

Question 4

A reaction mixture initially contains $$[A] = 1.0\ \mathrm{mol/L}$$ and $$[B] = 2.0\ \mathrm{mol/L}$$ for the reaction $$A \rightleftharpoons B. At $$equilibrium, $$[A] = 0.40\ \mathrm{mol/L}. $$What is the value of the equilibrium constant $$K$$?

Accepted Answer

$$K = \dfrac{[B]_{eq}}{[A]_{eq}} = \dfrac{1.6}{0.4} = 4.0$$

Question 5

For the reaction $$2\mathrm{SO}_2(g) \rightleftharpoons 2\mathrm{SO}_3(g) + \mathrm{O}_2(g)$$, the initial pressure of $$\mathrm{SO}_2 is$$ $$2.43$$ bar and at equilibrium it is $$1.10$$ bar. What is the change in pressure of $$\mathrm{SO}_2$$ and $$\mathrm{O}_2$$?

Accepted Answer

$$\Delta P$$_{\mathrm{SO}$$_2} = -1.33$$ bar, $$\Delta P$$_{\mathrm{O}$$_2} = +0.665$$ bar

Question 6

If $$Q \u003c K$$ for a chemical reaction, what will be the direction of the reaction's shift?

Accepted Answer

The reaction will shift to the right (toward products) until equilibrium is reached.

Question 7

For the reaction $$\mathrm{N_2O_4(g) \rightleftharpoons 2NO_2(g)}$$, if $$P_{\mathrm{NO_2$}} = 0.60$$ bar and $$P_{\mathrm{N_2O_4}} = 0.10$$ bar, what is the value of $$Q$$ and what does it indicate about the direction of the reaction if $$K = 0.30$$?

Accepted Answer

$$Q = \dfrac{(0.60)^2$}{0.10} = 3.6$$, so the reaction will shift to the left.

Question 8

A reaction has $$K = 49.7 at a $$certain temperature. For the system $$\mathrm{H_2$(g) + I_2$(g) \rightleftharpoons 2HI(g)}$$, if the initial pressures are $$P_{\mathrm{H_2$}} = 1.00$$ bar, $$P_{\mathrm{I_2$}} = 2.00$$ bar, and $$P_{\mathrm{HI}} = 0$$, which of the following is a valid equilibrium value for $$x if$$ $$x is $$the change in pressure of $$\mathrm{H_2$}$$ consumed?

Accepted Answer

$$x = 0.93 ($$since it keeps all equilibrium pressures positive)

Question 9

For the reaction $$2\mathrm{NOCI(g)} ightleftharpoons 2\mathrm{NO(g)} + \mathrm{Cl_2$(g)}$$, $$K = 1.65 	imes 10$$^{-5}$$ at a certain temperature. If the initial pressure of $$\mathrm{NOCI}$$ is 0.50$ bar and the change in pressure is 2x$, what is the equilibrium pressure of $$\mathrm{NOCI}$$ if x = 1.0$$ 	imes $$10^{-3}$$?

Accepted Answer

$$0.50 - 2x = 0.498$$\ bar

Question 10

If you reverse a chemical equation, how does the equilibrium constant for the new reaction relate to the original?

Accepted Answer

The new equilibrium constant is the reciprocal of the original: $$K_{	ext{new}} = 1/K_{	ext{original}}$$

Question 11

A vessel contains only $$\mathrm{SO_2$} at a $$pressure of $$2.43$$ bar. At equilibrium, $$\mathrm{SO_2$}$$ pressure is $$1.10$$ bar for the reaction $$2\mathrm{SO_2$(g)} \rightleftharpoons 2\mathrm{SO_3$(g)} + \mathrm{O_2$(g)}. $$What is the equilibrium pressure of $$\mathrm{O_2$}$$?

Accepted Answer

$$0.665$$ bar

Question 12

For the reaction $$\mathrm{I_2$(g) + Br_2$(g) \rightleftharpoons 2IBr(g)}$$, if the equilibrium pressure of $$\mathrm{IBr} is$$ $$17.6$$ bar, what is the equilibrium pressure of $$\mathrm{I_2$} if$$ $$x is $$the change in $$\mathrm{IBr}$$ pressure?

Accepted Answer

$$\dfrac{1}{2}x$$

Question 13

Which of the following best describes the use of an ICE table in solving equilibrium problems?

Accepted Answer

It helps organize initial, change, and equilibrium values for all species to systematically solve for unknowns.

Question 14

A chemical process in industry is only profitable if the equilibrium concentration of product is high. Which of the following would increase the equilibrium yield of product for an exothermic reaction?

Accepted Answer

Lowering the temperature

Question 15

If the equilibrium constant $$K$$ for a reaction is much less than 1, what does this indicate about the position of equilibrium?

Accepted Answer

The equilibrium favors the reactants.

Question 16

For the reaction $$\mathrm{A(g) + B(g) \rightleftharpoons C(g) + D(g)}$$, $$K_1 is $$the equilibrium constant for $$\mathrm{A(g) \rightleftharpoons C(g)}$$ and $$K_2$$ for $$\mathrm{B(g) \rightleftharpoons D(g)}. $$What is the equilibrium constant for $$\mathrm{A(g) + B(g) \rightleftharpoons C(g) + D(g)}$$?

Accepted Answer

$$K_1$$ 	imes $$K_2$$

Question 17

A reaction mixture has $$Q = 0.30$$ and $$K = 0.50. $$What will happen as the system moves toward equilibrium?

Accepted Answer

The reaction will proceed to the right, forming more products.

Question 18

In solving for equilibrium concentrations, why might a quadratic equation yield two solutions, and how do you determine which is valid?

Accepted Answer

Only the solution that gives all positive equilibrium concentrations is valid.

Chemical Equilibrium: Equilibrium Constants, Reaction Quotient, and Calculating Equilibrium Concentrations

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