What is the minimum pH required to prevent the precipitation of ZnS in a solution that is 0.01 M Z n C l 2 and saturated with 0.10 M H 2 S ? G i v e n K s p = 10 - 21 , K a 1 × K a 2 = 10 - 20

Step-by-step solution

Z n S ⇌ Z n 2 + + S 2 - K s p = Z n 2 + S 2 - Z n C l 2 → Z n 2 + + 2 C l - S 2 - = K s p Z n 2 + = 10 - 21 0.01 ⇒ S 2 - = 10 - 19 K a 1 . K a 2 = H + 2 S 2 - H 2 S Where, K a 1 = [ H S - ] [ H + ] H 2 S K a 2 = H + S 2 - H S - So, 10 - 20 = H + 2 S 2 - H 2 S = H + 2 10 - 19 0.1 ⇒ H + = 0.1 ⇒ p H = - log ⁡ H + = 1