Chapter 15: Equilibria of Other Reaction Classes

Question 1

Which of the following is the correct equilibrium equation for the solubility equilibrium of La(IO₃)₃?

a.) La(IO3)3 (aq) — La3+ (aq) + 3IO3- (aq)
b.) La3+ (aq) + IO3- (aq) — La3+ (aq) + (IO3)33- (aq)
c.) La(IO3)3 (aq) — La3+ (aq) + (IO3)33- (aq)
d.) La(IO3)3 (s) — La3+ (aq) + 3 IO3- (aq)

Answer 1

d.) La(IO3)3 (s) — La3+ (aq) + 3 IO3- (aq)

Question 2

Adding NaF to a solution of PbF₂ will

a.) increase the solubility of PbF₂
b.) decrease the solubility of PbF₂
c.) has no effect on the solubility of PbF₂

Answer 2

b.) decrease the solubility of PbF₂

Adding NaF will add more fluoride ions to the solution. Consider Le Chatelier’s principle. Adding more product will shift the equilibrium toward the reactants. This would result in a decreased solubility of PbF₂.

Question 3

For which of the following aqueous solutions will a decrease of pH increase the solubility?

a.) CaCO3
b.) PbCl2
c.) CuBr
d.) AgCl

Answer 3

a.) CaCO3

has a weak base that could react with H+

Question 4

The solubility of a salt refers to

a.) the concentration of all ions in the solution.
b.) how much of a salt will dissolve.
c.) the equilibrium constant associated with a solubility equilibrium.
d.) how many ions a salt dissociates into.

Answer 4

b.) how much of a salt will dissolve.

Question 5

A decrease in pH will increase the solubility of CaCO₃ because

a.) Ca2+ is a weak base.
b.) Ca2+ is an acidic ion.
c.) CO32- is a weak base.
d.) this compound would have decreased solubility at low pH.

Answer 5

c.) CO32- is a weak base.

Question 6

What is the solubility of MgCO₃ in water? (Ksp of MgCO₃ is 3.5 × 10⁻⁸)

Answer 6

1.9 × 10⁻⁴ M

Question 7

The solubility of Ag₃PO₄ in water at 25 °C is 4.3 × 10⁻⁵ M. What is Ksp for Ag₃PO₄?

Answer 7

9.2 × 10⁻¹⁷

Question 8

Which of the following would decrease the solubility of a 0.10 M solution of Ag₂CO₃ the most? (Ksp of Ag₂CO₃ is 8.1 × 10⁻¹²)

a.) adding 0.10 M H+
b.) adding 0.10 M Co32-
c.) adding 0.10 M Ag+

Answer 8

c.) adding 0.10 M Ag+

Question 9

A solution prepared in the lab contains 3.5 × 10⁻⁴ M Sr²⁺ and 0.0010 M F⁻. Will a precipitate form? (Ksp of SrF₂ is 4.3 × 10⁻⁹)

a.) Yes, because Q < Ksp.
b.) Yes, because Q > Ksp.
c.) No, because Q < Ksp.
d.) No, because Q > Ksp.

Answer 9

c.) No, because Q < Ksp.

Question 10

What is the maximum concentration of Ag⁺ that can be added to a 0.00360 M solution of Na₂CO₃ before a precipitate will form? (Ksp for Ag₂CO₃ is 8.10 × 10⁻¹²)

Answer 10

4.74 × 10⁻⁵ M

Question 11

The reason complex ion formation can increase the solubility of insoluble compounds is

a.) the complex ions formed precipitate.
b.) the complex ions shift the solubility equilibrium forward by moving the cation from the solution.
c.) the complex ions shift the solubility equilibrium in the reverse direction by adding extra ions to the solution.
d.) complex ions are more soluble in general.

Answer 11

b.) the complex ions shift the solubility equilibrium forward by moving the cation from the solution.

Question 12

Identify the best reasoning below as to why CO₂ is a Lewis acid.

a.) the oxygen carries a partial negative charge so it can donate a pair of electrons.
b.) the oxygen reacts with water to form hydroxide ions.
c.) the carbon carries a partial positive charge so it can accept a pair of electrons.
d.) the carbon releases the oxygen to the water forming H2O2.

Answer 12

c.) the carbon carries a partial positive charge so it can accept a pair of electrons.

Question 13

Which of the following is a Lewis acid?

a.) Fe3+
b.) CN-
c.) NH3
d.) SCN-

Answer 13

a.) Fe3+

Question 14

Identify the Lewis base in the following reaction.

BeCl₂ + 2 Cl⁻ → BeCl₄²⁻

a.) BeCl2
b.) BeCL42-
c.) Cl-

Answer 14

c.) Cl-