Question

(a) If the molar solubility of SrC₂O₄ at 25 ^oC is 0.000224 mol/L, what is the K_sp at this temperature?
K_sp =
(b) It is found that 8.70e-09 g of Ga(OH)₃ dissolves per 100 mL of aqueous solution at 25 ^oC. Calculate the solubility-product constant for Ga(OH)₃.
K_sp =
(c) The K_sp of ScF₃ at 25 ^oC is 5.81e-24. What is the molar solubility of ScF₃?
solubility = (mol/L)

Answer 1

(a)

SrC2O4 (s)   ------------> Sr2+ (aq) + C2O42- (aq)

                                         s                       s

Ksp = [Sr2+][C2O42-]

      = s^2

     = (0.000224)^2

Ksp = 5.02 x 10^-8

b)

solubility = 8.70 x 10^-9 g / 100 mL

               = 8.70 x 10^-8 g / L

                = 7.205 x 10^-10 mol / L

Ga(OH)3 (s) ------------>   Ga3+ (aq) + 3 OH- (aq)

                                             s                   3s

Ksp = [Ga3+][OH-]^3

       = s x (3s)^3

       = 27 s^4

      = 27 x (7.205 x 10^-10)^4

Ksp = 7.28 x 10^-36

c)

ScF3 (s)   ----------> Sc3+ (aq) + 3 F- (aq)

                                   s                    3s

Ksp = [Sc3+][F-]^3

5.81 x 10^-24 = s x (3s)^3

s = 6.81 x 10^-7 M

solubility = 6.81 x 10^-7 mol / L