An aqueous solution of hydrogen sulphide shows the equilibrium: `H_(2) S hArr H^(o+)+HS^(ɵ)`
If dilute hydrochloric acid is added to an aqueous solution of `H_(2)S`, without any change in temperature, the
a. The equilibrium constant will change.
b. The concentration `HS^(ɵ)` will increase.
c. The concentration of un-dissociated hydogen sulphide will decrease.
d. The concentration of `HS^(ɵ)` will decrease.

Options

A. The equilibrium constant change
B. The concentration `HS^(-)` will increase
C. The concentration of un-dissociated hydrogen sulphide will decrease
D. The concentration of `HS^(-)` will decrease

Answer

D

Explanation

`H_(2)S(aq) rarr H^(+)(aq) + HS^(-)(aq)`
Adding of dilute HCl(aq) will increase the concentration `H^(+)` ions in the solution leading to a backward shift in the reaction to re-establish the equilibrium state. This means the concentration of `HS^(-)` decreases.