Question

The best explanation for the dissolution of ZnS in dilute HCl is that a. the sulfide ion concentration is decreased by the formation of H2S. b. the zinc ion is amphoteric. c. the zinc ion concentration is decreased by the formation of a chloro complex. d. the sulfide ion concentration is decreased by oxidation to sulfur. e. the solubility product of ZnCl2 is less than that of ZnS.

Answer 1

Correct option is (a).

Step-by-step explanation:

Solubility equilibrium of ZnS is represented as-

`ZnS\rightleftharpoons Zn^(2+)+S^(2-)`

`S^(2-)` is a strong conjugate base of weak acid
`H_(2)S`.

Therefore addition of HCl in ZnS results formation of
`H_(2)S`. Thus
`S^(2-)` is removed as
`H_(2)S`.

`S^(2-)+2H^(+)\rightleftharpoons H_(2)S`

So, ZnS tends to be more soluble with addition of dilute HCl to keep constant solubility product.