Equilibrium Practice Test

Equilibrium

Practice Test

AP Chem

Multiple Choice

1. 0.200 mol NO is placed in a one liter flask at 2273 K. After equilibrium is attained, 0.0863 mol N₂ and 0.0863 mol O₂ are present. What is Kc for this reaction?

2NO(g) N₂(g) + O₂(g) a) 9.92 d) 39.7 b) 3.15 e) 0.576

c) 0.0372

2. For the equilibrium system

H₂O(g) + CO(g) H₂(g) + CO₂(g)

H = -42 kJ/mol

K_c equals 0.62 at 1260 K. If 0.10 mole each of H₂O, CO, H₂ and CO₂ (each at 1260 K) were placed in a 1.0-Liter flask at 1260 K, when the system came to equilibrium…

The temperature would

The mass of CO would a) decrease increase b) decrease decrease c) remain constant increase d) increase decrease e) increase increase

3. For the reaction system,

N₂(g) + 3H₂(g) 2NH₃(g) + heat the conditions that would favor maximum conversion of the reactants to products would be

a) high temperature and high pressure b) high temperature, pressure unimportant c) high temperature and low pressure d) low temperature and high pressure e) low temperature and low pressure

4. Solid HgO, liquid Hg, and gaseous O₂ are placed in a glass bulb and are allowed to reach equilibrium at a given temperature.

2HgO(s) 2Hg(l) + O₂(g) H = +43.4 kcal The mass of HgO in the bulb could be increased by

a) adding more Hg. b) removing some O₂.

c) reducing the volume of the bulb. d) increasing the temperature. e) removing some Hg.

5. Which one of the following is the solubility product constant for Mn(OH)2?

a) Ksp = [Mn2+][OH]2

b) Ksp = [Mn2+][2 OH]2

c) Ksp = [Mn2+]2[OH]2

d) Ksp = [Mn2+]2[OH]

e) Ksp = [Mn2+]2[2 OH]2

6. The solubility of HgS is 5.5 x 1027 _mol/L.

What is Ksp for HgS?

a) 4.0 x 103 _{d) 7.4 x 10}14

b) 8.2 x 104 _{e) 3.0 x 10}53

c) 1.3 x 1013

7. Which expression best describes the

relationship between solubility product, Ksp,

and the solubility, s, of MgF2?

a) Ksp = 2s d) Ksp = 4s2

b) Ksp = s2 e) Ksp = 4s3

8. Calculate the molar solubility of Fe2S3.

Ksp = 1.4 x 1088

a) 5.5 x 1062 _{M d) 4.8 x 10}24 _M

b) 1.2 x 1044 _{M e) 1.1 x 10}18 _M

c) 5.2 x 1030 _M

9. What is the concentration of CrO42 in a

saturated solution of PbCrO4?

Ksp = 1.8 x 1014?

a) 1.3 x 107 _{M d) 1.3 x 10}4 _M

b) 7.5 x 106 _{M e) 5.1 x 10}3 _M

c) 1.8 x 104 _M

10. Calculate the equilibrium constant for the reaction:

CuCl(s) + I_{(aq) CuI(s) + Cl}_(aq)

CuCl; Ksp = 1.9 x 107

CuI; Ksp = 5.1 x 1012

a) 8.4 x 102 _{d) 4.4 x 10}17

b) 2.3 x 106 _{e) 9.7 x 10}-19

c) 3.7 x 104

11. For BaSO4, Ksp = 1.1 x 1010. If you mix 200.

mL of 1.0 x 10-4 _{M Ba(NO}

3)2 and 500. mL of

8.0 x 102 _{M H}

2SO4, what will be observed?

a) A precipitate forms because Qsp > Ksp

b) A precipitate forms because Qsp < Ksp

c) No precipitate forms because Qsp = Ksp

d) No precipitate forms because Qsp < Ksp

e) No precipitate forms because Qsp > Ksp

12. Calculate the molar solubility of AgCl in a 0.10 M solution of NaCl.

Ksp of AgCl is 1.8 x 1010

a) 1.3 x 105 _{M d) 4.2 x 10}5 _M

b) 5.5 x 10 _{M e) 4.8 x 10}4 _M

c) 1.8 x 109 _M

13. The solubility of salts can be affected by other equilibria. Addition of all of the following will affect the solubility of FeCO3 EXCEPT:

a) NaHCO3 d) Na2CO3

b) NaCl e) HCl c) H2CO3

Simple Free Response

1. Predict, on the basis of the solubility rules, which of the following salts are soluble and which are insoluble.

a. AgI c. BaSO4 e. NiCO3

b. Na3PO4 d. (NH4)2SO4 f. Cu(OH)2

2. Write solubility product expressions for the following salts:

a. PbSO4 c. CuS

b. Ca3(PO4)2 d. CaF2

3. If the molar concentration of lead bromide, PbBr2, in an aqueous solution is 1.6 x 10-6 M, what is [Pb2+]

and [Br-_]?

5. What is the molar solubility of cadmium sulfide, CdS, if its Ksp = 3.6 x 10-29?

6. Ksp of strontium fluoride, SrF2, is 2.5x 10-9. What is the [Sr2+] and [F-] in a saturated solution of SrF2?

What is the molar solubility of SrF2?

Free Response

7. What is the [Mg2+_{] in a saturated solution of magnesium fluoride, MgF}

2 if its solubility product constant is

6.4 x 10-9_{? What is the [Mg}2+_{] if the solution also contains 0.30 M sodium fluoride?}

8. From which of the following mixtures of silver nitrate and sodium sulfite would silver sulfite precipitate? The Ksp for silver sulfite = 1.5 x 10-14.

a. 50 mL of 1.0 x 10-4 _{M Ag}+ _{and 50 mL of 1.0 x 10}-4 _{M SO} 32-.

b. 25 mL of 1.0 x 10-3 _{M Ag}+ _{and 25 mL of 1.0 x 10}-5 _{M SO} 32-.

c. 50 mL of 1.0 x 10-5 _{M Ag}+ _{and 100 mL of 1.0 x 10}-3 _{M SO} 32-.

9. CH4(g) + H2O(g)  CO(g) + 3 H2(g) Kc = 5.7 at 1773 K

A. What is the equilibrium expression for this reaction in terms of Kc?

B. Suppose that the initial concentrations for all species at 1773 K are: [CH4] = 0.125 M, [H2O] = 0.176 M, [CO] = 0.538 M, and [H2] = 0.993 M

b. In what direction will the reaction proceed at this temperature? Justify your answer.

C. Calculate the value of the equilibrium constant, Kp, for this reaction at 1773 K.

D. Calculate the value for the free energy change, ΔG°1773K, of this reaction. Include units with your

answer.

E. The equilibrium concentrations of CO and H2 increase when the temperature of the system increases. Is the forward reaction exothermic or endothermic? Justify your answer.

F. Calculate the value of Kc for the following reaction.

CO(g) + 3 H2(g)  CH4(g) + H2O(g)

G. Calculate the value of Kc for the following reaction.

3 CH4(g) + 3 H2O(g)  3 CO(g) + 9 H2(g)

10. The equilibrium constant, Kp, for the reaction below is 1.4 x 10-21 _{at 25C.}

H2(g) + Br2(g)  2 HBr (g)

A. Write the expression for the equilibrium constant, Kp.

B. Gaseous H2 and Br2 are added to an evacuated 1.15 L container kept at 298 K. The initial partial pressure

of H2(g) is 0.782 atm and that of Br2(g) is 0.493 atm. Find the partial pressures of HBr when the system

reaches equilibrium.

11.

NH4Cl(s) NH3(g) + HCl(g)H = +42.1 kilocalories

Suppose the substances in the reaction above are at equilibrium at 600K in volume V and at pressure P. State whether the partial pressure of NH3(g) will have increased, decreased, or remained the same when equilibrium is reestablished after each of the following disturbances of the original system. Some solid NH4Cl remains in

the flask at all times. Justify each answer with a one-or-two sentence explanation. (a) A small quantity of NH4Cl is added.\

(b) The temperature of the system is increased.

(c) The volume of the system is increased.

(d) A quantity of gaseous HCl is added.

Net Ionic Equations

A. Calcium nitrate is mixed with sodium phosphate.

(ii) If a flame test were conducted on the solution, what color would one expect to see?

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B. A solution of magnesium hydroxide is added to a solution of magnesium chloride.

(ii) What is the name of the group on the periodic table in which magnesium and calcium are found?

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(ii) What is color is the precipitate?

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C. A solution of potassium phosphate is added to aluminum nitrate.

(ii) What are the spectator ions?

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(i) Balanced equation:

(i) Balanced equation: