Question

Which of the following substances has the greatest solubility in water?

A. MgCO3, Ksp= 3.5x10^-8

B. NiCO3, Ksp=1.3x10^-7

C. AgIO3, Ksp=3.1x10^-8

D. CuBr, Ksp= 5.0x10^-9

Answer 1

A) Let x mol/L be the solubility of MgCO₃. Write down the dissociation reaction.

MgCO₃ (s) <=====> Mg²⁺ (aq) + CO₃^2- (aq)

K_sp = [Mg²⁺][CO₃^2-] = (x).(x) (1:1 nature of dissociation)

===> 3.5*10^-8 = x²

===> x = 1.87*10^-4

The solubility of MgCO₃ is 1.87*10^-4 mol/L (ans).

B) Let x mol/L be the solubility of NiCO₃. Write down the dissociation reaction.

NiCO₃ (s) <=====> Ni²⁺ (aq) + CO₃^2- (aq)

K_sp = [Ni²⁺][CO₃^2-] = (x).(x) (1:1 nature of dissociation)

===> 1.3*10^-7 = x²

===> x = 3.60*10^-4

The solubility of NiCO₃ is 3.60*10^-4 mol/L (ans).

C) Let x mol/L be the solubility of AgIO₃. Write down the dissociation reaction.

AgIO₃ (s) <=====> Ag⁺ (aq) + IO₃^- (aq)

K_sp = [Ag⁺][IO₃^-] = (x).(x) (1:1 nature of dissociation)

===> 3.1*10^-8 = x²

===> x = 1.76*10^-4

The solubility of AgIO₃ is 1.76*10^-4 mol/L (ans).

D) Let x mol/L be the solubility of CuBr. Write down the dissociation reaction.

CuBr (s) <=====> Cu⁺ (aq) + Br^- (aq)

K_sp = [Cu⁺][Br^-] = (x).(x) (1:1 nature of dissociation)

===> 5.0*10^-9 = x²

===> x = 7.07*10^-5

The solubility of AgIO₃ is 7.07*10^-5 mol/L (ans).

Since the solubility of NiCO₃ is the highest, hence NiCO₃ has the highest solubility (ans).