Question

Calculate the molar solubility of Cd(OH)2 when buffered at a pH = 12.30. The Ksp for Cd(OH)2 is 2.5 x 10-14. Calculate the molar solubility of Cd(OH)2 when buffered at a pH = 12.30. The Ksp for Cd(OH)2 is
a.2.5 x 10-14 M.
b. 8.5 x 10-6 M
c. 6.3 x 10-11 M
d. 1.3 x 10-12 M
e. 5.0 x 10-2 M
f. 1.8 x 10-5 M

Answer 1

Answer:

c. 6,3x10⁻¹¹M

Explanation:

The solubility of a buffer is defined as the concentration of the dissolved solid in a saturated solution. For the Cd(OH)₂, solubility is:

[Cd²⁺] = S

The dissolution of Cd(OH)₂ is:

Cd(OH)₂ ⇄ Cd²⁺ + 2OH⁻

And the ksp is defined as:

ksp = [Cd²⁺][OH⁻]²

As ksp = 2,5x10⁻¹⁴ and [OH⁻] at pH=12,30 = 10^-(14-12,30) = 0,01995M

2,5x10⁻¹⁴ = [Cd²⁺]×(0,01995M)²

[Cd²⁺] = 6,3x10⁻¹¹M

That means solubility is c. 6,3x10⁻¹¹M

I hope it helps!