Question

Calculate the k sp for zinc hydroxide if the solubility of zn (oh)2 in pure water is 2.1 × 10-4 g/l. calculate the k sp for zinc hydroxide if the solubility of zn (oh)2 in pure water is 2.1 × 10-4 g/l. 2.9 × 10-3 1.5 × 10-3 9.9 × 10-18 3.8 × 10-17

Answer 1

Zinc hydroxide is a uni-bi type of electrolyte.
For such systems, k sp = 4S^3
where S = solubility in mol/l

Now for Zinc hydroxide, molecular weight = 99.4

so,  solubility = 2.1 x 10-4 g/l = 2.11 X 10^-6 mol/l
Finally, k sp = 4S^3 = 4 X (2.11 X 10^-6)^3 = 3.77 X 10^-17