Quiz #4 – Writing and Calculating Keq

Quiz #4 Writing and Calculating Keq

1. The equilibrium constant expression for the following reaction is:

2Hg₍_l) + O_2(g)⇄ 2HgO_(s)

A. K_eq = 1/[O₂]

B. K_eq = [O₂]

C. K_eq = [2HgO] / [O₂] [2Hg]

D. Keq = [HgO]² / [Hg]²[O₂]

2. Identify the equilibrium system that least favors the formation of products

A. 2HgO_(s) ⇄ 2Hg₍_l) + O_2(g) K_eq = 1.2 x 10^-22

B. CH₃COOH₍_aq₎ + H₂O_(l) ⇄ H₃O⁺_(aq) + CH₃COO^-_(aq)K_eq = 1.8 x 10^-5

C. 2NO₍_g) + O_2(g)⇄2NO_2(g) K_eq = 6.5 x 10⁵

D. H₂₍_g) + Cl_2(g) ⇄ 2HCl_(g) K_eq = 1.8 x 10³³

3. Consider the following equilibrium system: 3O₂₍_g) ⇄ 2O_3(g)K_eq = 1

Which equation compares the concentration of oxygen and ozone?

A. [O₂] = [O₃]^2/3

B. [O₂] = [O₃]

C. [O₂] = [O₃]^3/2

D. [O₂]^2/5 = [O₃]

4. For which of the following equilibrium does K_eq = [O₂]

A. O₂₍_l) ⇄ O_2(g)

B. 2O₃₍_g) ⇄ 3O_2(g)

C. 2H₂O₍_l) ⇄ 2H_2(g)+ O_2(g)

D. 2Hg_{(s) +} O_2(g)⇄ 2HgO_(s)

5. Consider the following equilibrium system at 25^OC :

2SO₂₍_g)+ O_2(g) ⇄ 2SO_3(g)

At equilibrium, [SO₂] is 4.00 x 10^-3 mol/L, [O₂] = 4.00 x 10^-3 mol/L and

[SO₃] is 2.33 x 10^-3 mol/L. From this data, the K_eqvalue for the above system is

A. 6.85 x 10^-3

B. 1.18 x 10^-2

C. 84.8

D. 146

6. Consider the following equilibrium system: PCl₅₍_g)⇄ PCl_3(g)+ Cl_2(g)

At equilibrium, [PCl₅] is a 0.400 M. [PCl₃] is 1.50 M and [Cl₂] is 0.600 M.

The K_eq for the reaction is

A. 0.360

B. 0.444

C. 0.900

D. 2.25

7. Consider the following equilibrium: 2H₂S₍_g) ⇄ 2H_2(g) + S_2(g)

At equilibrium, [H₂S] = 0.50 mol/L. [H₂] = 0.10 mol/L and [S₂] = 0.40 mol/L.

The value of K_eq is calculated using the ratio

A (0.10)(0.40)

(0.50)

B. (0.10)²(0.40)

(0.50)²

C. (0.50)

(0.10)(0.50)

D. (0.50)²

(0.10)²(0.40)

8. Consider the following equilibrium: 2NO₍_g) + Cl_2(g) ⇄ 2NOCl_(g) K_eq = 12

At equilibrium, [NOCl] = 1.60 mol/L and [NO] = 0.80 mol/L. The [Cl₂] is

A. 0.17 mol/L

B. 0.27 mol/L

C. 0.33 mol/L

D. 3.0 mol/L

9. Consider the following equilibrium: I_2(s)+ H₂O_(l) ⇄ H⁺_(aq) + I^-_(aq)+ HOI_(aq)

The equilibrium constant expression for the above system is

A. K_eq = [H⁺][I^-]

B. K_eq = [H⁺][I^-][HOI]

C. K_eq = [H⁺][I^-][HOI]

[I₂][H₂O]

D. K_eq = [H⁺][I^-][HOI]

[H₂O]

10. Consider the following equilibrium: 2CO₍_g) + O_2(g)⇄ 2CO_2(g)

The ratio used to calculate the equilibrium constant is

A. [2CO]²[O₂]

[2CO₂]²

B. [2CO₂]²

[2CO]²[O₂]

C. [CO]²[O₂]

[CO₂]²

D. [CO₂]²

[CO]²[O₂]

11. Consider the following equilibrium: 2Fe_{(s) +} 3H₂O_(g) ⇄ Fe₂O_3(s)+ 3H_2(g)

The equilibrium constant expression is

A. K_eq = [Fe₂O₃][H₂]³

[Fe]²[H₂O]³

B. K_eq = [Fe₂O₃][3H₂]

[2Fe] [3H₂O]

C. K_eq = [H₂]³

[H₂O]³

D. K_eq = [H₂]³

12. Consider the following equilibrium: N₂O₄₍_g) ⇄ 2NO_2(g) K_eq = 0.133

At equilibrium, the [N₂O₄] is equal to

A. 0.133

[NO₂]

B. [NO₂]

0.133

C. 0.133

[NO₂]²

D. [NO₂]²

0.133

13. Consider the following equilibrium: 4KO_{2(s) +} 2H₂O_(g) ⇄ 4KOH_(s)+ 3O_2(g)

The equilibrium constant expression is

A. K_eq = [KOH]⁴[O₂]³

[KO₂]⁴[H₂O]²

B. K_eq = [O₂]³

[H₂O]²

C. K_eq = [KO₂]⁴[H₂O]²

[KOH]⁴[O₂]³

D. K_eq = [H₂O]²

[O₂]³

14. Consider the following equilibrium: C_{(s) +} H₂O_(g) ⇄ CO_(g) + H_2(g)

The contents of a 1.00 L container at equilibrium were analyzed and found to

contain 0.20 mol C, 0.20 mol H₂O, 0.60 mol CO and 0.60 mol H₂. The equilibrium constant is

A. 0.11

B. 0.56

C. 1.8

D. 9.0

15. Consider the following equilibrium: N₂O₄₍_g) ⇄ 2NO_2(g) K_eq = 4.61 x 10^-3

A 1.00 L container at equilibrium was analyzed and found to contain

0.0200 moles NO₂. At equilibrium, the concentration of N₂O₄ is

A. 0.0868 mol/L

B. 0.230 mol/L

C. 4.34 mol/L

D. 11.5 mol/L

16. Consider the following equilibrium: CH₄₍_g)+ H₂O_(g) ⇄ CO_(g) + 3H_2(g)K_eq= 5.7

At equilibrium, the [CH₄] = 0.40 mol/L [CO] = 0.30 mol/L and

[H₂] = 0.80 mol/L. The [H₂O] is

A. 0.067 mol/L

B. 0.11 mol/L

C. 2.2 mol/L

D. 5.3 mol/L

17. Consider the following equilibrium: H₂₍_g)+ I_2(g)⇄ 2HI_(g)

At equilibrium, the [H₂] = 0.020 mol/L. [I₂] = 0.020 mol/L

and [HI] = 0.160 mol/L. The value of the equilibrium constant is

A. 2.5 x 10^-3

B. 1.6 x 10^-2

C. 6.4 x 10¹

D. 4.0 x 10²

18. Consider the following constant expression: K_eq = [CO₂]. Which one of the following equilibrium

systems does the above expression represent?

A. CO₂₍_g) ⇄ CO_2(s)

B. PbO_{(s) +} CO_2(g) ⇄ PbCO_3(s)

C. CaCO_3(s) ⇄ CaO_(s) + CO₂_(g)

D. H₂CO₃₍_aq₎ ⇄ H₂O_(l) + CO_2(aq)

19. Given the following equilibrium system: Br₂₍_g) ⇄ Br_2(l)

The equilibrium constant expression for the above system is

A. K_eq = [Br₂₍_l)]

[Br₂₍_g)]

B. K_eq = [Br₂₍_g)]

C. K_eq = 1 __

[Br₂₍_g)]

D. K_eq = [Br₂₍_g)] [Br_2(g)]

20. Consider the following equilibrium: CO₍_g) + 2H_2(g)⇄CH₃OH_(g) + 91 kJ

A change in temperature of the above system increases the value of the equilibrium constant.

The new state of equilibrium was established by a shift

A. Left as a result of a decrease in temperature

B. Right as a result of a decrease in temperature

C. Left as a result of an increase in temperature

D. Right as a result of an increase in temperature

21. Consider the equilibrium: SrCO_3(s) ⇌ SrO_(s) + CO_2(g) In a 2.5 L container

at equilibrium there are 2.42 g CO₂, 1.00 g SrCO₃ and 1.00 SrO.

Which of the following is the value of Keq?

A. 0.022

B. 0.011

C. 0.020

D. 91

22. Consider the following equilibrium: CCl₄₍_g) ⇌ C_(s) + 2Cl_2(g)

Initially, 0.62 mol CCl₄ was placed in a 2.0L container.

At equilibrium, [Cl₂]= 0.060 M. Which of the following is the value of Keq?

A. 0.00039

B. 0.013

C. 0.014

D. 0.78

23. Consider the following equilibrium: CH₄₍_g) + H₂O_(g) ⇌ CO_(g) + 3H_2(g)

At equilibrium, 1.20 mol CH₄, 1.20 mol H₂O, 0.080 mol CO and 0.040 mol H₂

are present in a 2.0 L container. What is the value of Keq ?

A. 4.3 x 10^-6

B. 2.2 x 10^-2

C. 2.2 x 10^-4

D. 8.9 x 10^-7

24. Consider the following equilibrium: Cr₂O₇^2-_(aq)
+ 2OH^-_(aq)⇌ 2CrO₄^2-_(aq) + H₂O_(l)

The concentration of ions at equilibrium was measured at a specific temperature and found to be

[CrO₄^2-] = 0.100 M, [Cr₂O₇^2-] = 0.20 M, and [ OH^- ] = 0.11 M. What is the Keq?

A. 41

B. 4.13

C. 0.83

D. 0.11

25. Consider the following equilibrium:Cr₂O₇²^-_(aq)+ 2OH^-_(aq)⇌ 2CrO₄^2-_(aq) + H₂O_(l) Keq = 4.14

The concentration of ions at equilibrium was measured at a specific temperature and found to be

[Cr₂O₇^2-] = 0.100 M and [ OH^- ] = 0.20 M. What is the equilibrium [CrO₄^2-]?

A. 0.017 M

B. 0.083 M

C. 0.13 M

D. 0.32 M

26. Consider the following equilibrium: 2COF₂₍_g)⇌ CO_2(g) + CF_4(g)

Initially, 0.32 M CO₂ and 0.40 M CF₄ are placed in a container. At equilibrium, it is found that the

[COF₂] is 0.16 M. What is the value of Keq?

A. 0.026

B. 1.5

C. 9.3

D. 3.0

27. Consider the following equilibrium:Cr₂O₇²^-_(aq)+ 2OH^-_(aq)⇌ 2CrO₄^2-_(aq) + H₂O_(l) Keq = 4.14

The concentration of ions at equilibrium was measured at a specific temperature and found to be

[CrO₄^2-] = 0.100 M and [ OH^- ] = 0.20 M. What is the equilibrium [Cr₂O₇^2-]?

A. 0.060 M

B. 0.083 M

C. 0.13 M

D. 0.32 M

28. Consider the following equilibrium:Cr₂O₇^2-_(aq)+ 2OH^-_(aq)⇌ 2CrO₄^2-_(aq) + H₂O_(l) Keq = 4.14

The concentration of ions at equilibrium was measured at a specific temperature and found to be

[CrO₄^2-] = 0.100 M and [Cr₂O₇^2-] = 0.20 M. What is the equilibrium [OH^-]?

A. 0.012 M

B. 0.083 M

C. 0.13 M

D. 0.11 M

29. Consider the following equilibrium: 2COF₂₍_g)⇌ CO_2(g) + CF_4(g)Initially, 0.16 M CO₂ and 0.20 M CF₄

are placed in a container. At equilibrium, it is found that the [COF₂] is 0.080 M. What is the value of Keq?

A. 0.12

B. 1.5

C. 8.0

D. 3.0

30. Consider the following equilibrium: CH_4(g) + H₂O_(g) ⇌ CO_2(g)+ 3H_2(g)Keq = 5.67

An equilibrium mixture of this system was found to contain the following concentrations:

[CH₄] = 0.59 M , [H₂O] = 0.63 M, [CO₂] = 0.25 M.

What was the equilibrium [H₂]?

A. 0.26 M

B. 0.64 M

C. 2.0 M

D. 8.4 M

31. Consider the following equilibrium: 2COF_2(g)⇌ CO_2(g) + CF_4(g)

Initially, 0.32 M CO₂ and 0.40 M CF₄ are placed in a container. At equilibrium, it is found that the [COF₂] is 0.16 M.

What is the value of Keq?

A. 0.026

B. 1.5

C. 9.3

D. 3.0

32. Consider the following equilibrium: CCl_4(g) ⇌ C_(s) + Cl_2(g)

Initially, 0.62 mol CCl₄ was placed in a 2.0L container.

At equilibrium, [Cl₂]= 0.060 M. Which of the following is the value of Keq?

A. 0.00039

B. 0.24

C. 0.014

D. 0.78

33. Consider the following equilibrium: 2COF_2(g)⇌ CO_2(g) + CF_4(g)

Initially, 0.16 M CO₂ and 0.20 M CF₄ are placed in a container.

At equilibrium, it is found that the [COF₂] is 0.080 M.

What is the value of Keq?

A. 0.12

B. 1.5

C. 8.0

D. 3.0