What is the minimum pH required to prevent the precipitation of ZnS in a solution which is 0.01 M $Z n C l_{2}$ and saturated with 0.1 M $H_{2} S ?$
$K_{sp} of (ZnS) = 10^{- 21}, K_{a_{1}} × K_{a_{2}} (H_{2} S) = 10^{- 20}$

Question

What is the minimum pH required to prevent the precipitation of ZnS in a solution which is 0.01 M Z n C l 2 and saturated with 0.1 M H 2 S ? K sp of ZnS = 10 − 21 , K a 1 × K a 2 H 2 S = 10 − 20

TestHub · Accepted Answer

K sp = [Zn 2+ ] × [S 2 − ] [ S 2 - ] = K s p Z n S [ Z n 2 + ] = 1 0 - 21 0.01 = 1 0 - 19 K H 2 S = [ H + ] 2 - [ S 2 - ] [ H 2 S ] 10 − 20 = [ H + ] 2 × [ 10 − 19 ] 0.1 [ H + ] = 0.1 pH = 1

Chemistry - Ionic Equilibrium Question with Solution | TestHub

Options:

Doubts & Discussion