A solution is prepared by saturating 0.2 M HCl solution with hydrogen sulfide ( H₂S ) gas. The concentration of H₂S in the saturated solution is 0.1 M. If the first and second ionization constants of H₂S are 1.0 10⁻⁷ and 1.2 10⁻¹³ respectively, the concentration of sulfide ion ( S²⁻ ) in the resultant solution is:

Step-by-step solution

The overall dissociation of H₂S is given by: H₂S 2H^+ + S²⁻ The overall equilibrium constant K_ net is the product of the two ionization constants: K_ net = K_ a1 K_ a2 = (1.0 10⁻⁷) (1.2 10⁻¹³) = 1.2 10⁻²⁰ The equilibrium expression for the overall reaction is: K_ net = [H^+]^2[S²⁻] [H₂S] The solution contains 0.2 M HCl, which is a strong acid and dissociates completely. The H^+ contributed by the weak acid H₂S is negligible due to the common ion effect. Thus, [H^+] 0.2 M. The concentration of undissociated H₂S rem