Q: Given the reaction $$\mathrm{N_2$(g) + 3 H_2$(g) \rightleftharpoons 2 NH_3$(g)}$$ with $$K = 5.6 \times 10^5$, what is the equilibrium constant for the reverse reaction $$\mathrm{2 $$NH_3(g$$) \rightleftharpoons $$N_2(g) + 3$$ $$H_2(g$$)}$$?

$$K_{\text{reverse}} = \dfrac{1}{5.6 \times 10^5$}$$

Q: A reaction has $$K_p = 2.2 \times 10$$^{12}$$ at 25$$^\circ$$C. If $$\Delta n = -1$$, what is the value of K_c$? (Use R = 0.08206$$\ \mathrm{L \cdot atm \cdot $$mol^{-1}$$ \cdot $$K^{-1}$$}$$ and T = 298$$\ \mathrm{K}$$)

$$K_c = \dfrac{2.2 \times 10$$^{12}$$}{(0.08206 \times 298$$)^{-1}$$}$$

Q: For the decomposition of hydrogen disulfide $$\mathrm{2 H_2S(g) \rightleftharpoons 2 H_2$(g) + S_2$(g)}$$ with $$K_c = 1.67 \times 10$$^{-7}$$ at 800$$^\circ$$C, if the initial concentration of $$\mathrm{H_2S}$$ is 0.0250$$\ \mathrm{M}$$ in a 0.500$$\ \mathrm{L}$$ vessel, what is the equilibrium concentration of $$\mathrm{$$S_2$$}$$?

$$2.97 \times 10$$^{-4}$$\ \mathrm{M}$$

Question 1

Given the reaction $$\mathrm{N_2$(g) + 3 H_2$(g) ightleftharpoons 2 NH_3$(g)}$$ with $$K = 5.6 	imes 10^5$, what is the equilibrium constant for the reverse reaction $$\mathrm{2 $$NH_3(g$$) ightleftharpoons $$N_2(g) + 3$$ $$H_2(g$$)}$$?

Accepted Answer

$$K_{	ext{reverse}} = \dfrac{1}{5.6 	imes 10^5$}$$

Question 2

For the reaction $$\mathrm{NH_3$(g) \rightleftharpoons \frac{1}{2}N_2$(g) + \frac{3}{2}H_2$(g)}$$, what is the correct expression for the new equilibrium constant $$K' in $$terms of the original $$K$$ for $$\mathrm{N_2$(g) + 3 H_2$(g) \rightleftharpoons 2 NH_3$(g)}$$?

Accepted Answer

$$K' = K$$^{-1/2}$$

Question 3

A reaction has $$K_p = 2.2 	imes 10$$^{12}$$ at 25$$^\circ$$C. If $$\Delta n = -1$$, what is the value of K_c$? (Use R = 0.08206$$\ \mathrm{L \cdot atm \cdot $$mol^{-1}$$ \cdot $$K^{-1}$$}$$ and T = 298$$\ \mathrm{K}$$)

Accepted Answer

$$K_c = \dfrac{2.2 	imes 10$$^{12}$$}{(0.08206 	imes 298$$)^{-1}$$}$$

Question 4

Given the reaction $$\mathrm{CO(g) + 2 H_2$(g) \rightleftharpoons CH_3OH(g)}$$ with initial concentrations $$[\mathrm{CO}] = 0.500\ \mathrm{M}$$, $$[\mathrm{H_2$}] = 1.00\ \mathrm{M}$$, and $$[\mathrm{CH_3OH}] = 0.00\ \mathrm{M}$$, and at equilibrium $$[\mathrm{CO}] = 0.15\ \mathrm{M}$$, what is the equilibrium concentration of $$\mathrm{H_2$}$$?

Accepted Answer

$$0.30\ \mathrm{M}$$

Question 5

For the reaction $$\mathrm{2 CH_4$(g) \rightleftharpoons C_2H_2(g) + 3 H_2$(g)}$$, if the initial concentration of $$\mathrm{CH_4$} is$$ $$0.115\ \mathrm{M}$$ and at equilibrium $$[\mathrm{C_2H_2}] = 0.035\ \mathrm{M}$$, what is the equilibrium concentration of $$\mathrm{H_2$}$$?

Accepted Answer

$$0.105\ \mathrm{M}$$

Question 6

Given $$K_c = 2.00$$ for the reaction $$\mathrm{2 $$COF_2$$(g) \rightleftharpoons CO_2$(g) + CF_4$(g)} at$$ $$1000^\circC$$, $$[\mathrm{$$COF_2$$}] = 0.255\ \mathrm{M}$$, and $$[\mathrm{CF_4$}] = 0.118\ \mathrm{M} at $$equilibrium, what is $$[\mathrm{CO_2$}] at $$equilibrium?

Accepted Answer

$$[\mathrm{CO_2$}] = 1.10\ \mathrm{M}$$

Question 7

For the reaction $$\mathrm{N_2$(g) + O_2$(g) \rightleftharpoons 2 NO(g)}$$ with $$K_c = 0.10 at$$ $$2000^\circC$$, if the initial concentrations are $$[\mathrm{N_2$}] = 0.200\ \mathrm{M}$$, $$[\mathrm{O_2$}] = 0.200\ \mathrm{M}$$, and $$[\mathrm{NO}] = 0.00\ \mathrm{M}$$, what is the equilibrium concentration of $$\mathrm{NO}$$?

Accepted Answer

$$0.054\ \mathrm{M}$$

Question 8

For the reaction $$\mathrm{N_2O_4(g) \rightleftharpoons 2 NO_2$(g)}$$ with $$K_c = 0.36 at$$ $$100^\circC$$, if the initial concentration of $$\mathrm{NO_2$} is$$ $$0.100\ \mathrm{M}$$ and $$[\mathrm{N_2O_4}] = 0.00\ \mathrm{M}$$, what is the equilibrium concentration of $$\mathrm{N_2O_4}$$?

Accepted Answer

$$0.014\ \mathrm{M}$$

Question 9

For the reaction $$\mathrm{I_2$(g) + Cl_2$(g) \rightleftharpoons 2 ICl(g)}$$ with $$K_p = 81.9 at$$ $$25^\circC$$, if the initial partial pressures are $$P_{I_2$} = 0.100\ \mathrm{atm}$$, $$P_{Cl_2$} = 0.100\ \mathrm{atm}$$, and $$P_{ICl} = 0.100\ \mathrm{atm}$$, what is the direction of the reaction?

Accepted Answer

The reaction will proceed to the right.

Question 10

For the decomposition of hydrogen disulfide $$\mathrm{2 H_2S(g) ightleftharpoons 2 H_2$(g) + S_2$(g)}$$ with $$K_c = 1.67 	imes 10$$^{-7}$$ at 800$$^\circ$$C, if the initial concentration of $$\mathrm{H_2S}$$ is 0.0250$$\ \mathrm{M}$$ in a 0.500$$\ \mathrm{L}$$ vessel, what is the equilibrium concentration of $$\mathrm{$$S_2$$}$$?

Accepted Answer

$$2.97 	imes 10$$^{-4}$$\ \mathrm{M}$$

Question 11

If the reaction $$\mathrm{$$CaCO_3$$(s) \rightleftharpoons CaO(s) + CO_2$(g)} is at $$equilibrium and more $$\mathrm{CO_2$} is $$added, what will happen to the position of equilibrium?

Accepted Answer

It will shift to the left.

Question 12

For the reaction $$\mathrm{2 $$KClO_3$$(s) \rightleftharpoons 2 KCl(s) + 3 O_2$(g)}$$, what is the effect of decreasing the volume of the reaction mixture?

Accepted Answer

The equilibrium shifts to the left.

Question 13

For the endothermic reaction $$\mathrm{$$CaCO_3$$(s) \rightleftharpoons CaO(s) + CO_2$(g)}$$, what is the effect of increasing the temperature?

Accepted Answer

The equilibrium shifts to the right.

Question 14

Which of the following is the correct equilibrium expression for the reaction $$\mathrm{4 HCl(g) + O_2$(g) \rightleftharpoons 2 H_2O(l) + 2 Cl_2$(g)}$$?

Accepted Answer

$$K_c = \dfrac{[Cl_2$]^2}{[HCl]^4[O_2$]}$$

Question 15

A reaction mixture for $$\mathrm{I_2$(g) + Cl_2$(g) \rightleftharpoons 2 ICl(g)} at$$ $$25^\circC $$has $$P_{I_2$} = 0.114\ \mathrm{atm}$$, $$P_{Cl_2$} = 0.102\ \mathrm{atm}$$, and $$P_{ICl} = 0.355\ \mathrm{atm}. If$$ $$K_p = 81.9$$, what is the value of $$Q_p$$ and what does it indicate?

Accepted Answer

$$Q_p = 10.8$$, reaction will proceed to the right.

Question 16

For the reaction $$\mathrm{2 $$COF_2$$(g) \rightleftharpoons CO_2$(g) + CF_4$(g)}$$ with $$K_c = 2.00$$, $$[$$COF_2$$] = 0.255\ \mathrm{M}$$, and $$[CF_4$] = 0.118\ \mathrm{M}$$, what is the correct formula to calculate $$[CO_2$] at $$equilibrium?

Accepted Answer

$$[CO_2$] = K_c \dfrac{[$$COF_2$$]^2}{[CF_4$]}$$

Chemical Equilibrium: Expressions, Calculations, and Applications

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