The following equilibrium constants have been determined for hydrosulfuric acid at 25ºc:
h2s(aq) ⇌ h+(aq) + hs–(aq) k′c = 9.5 × 10^–8
hs–(aq) ⇌ h+(aq) + s2–(aq) k″c = 1.0 × 10^–19
calculate the equilibrium constant for the following reaction at the same temperature: h2s(aq) ⇌ 2h+(aq) + s2–(aq).

hey there!:

H2S(aq) <=> H⁺(aq) + HS⁻(aq)

K'c = [H⁺][HS⁻]/[H₂S] = 9.5*10⁻⁸

HS⁻(aq) <=> H⁺(aq) + S²⁻(aq)

K"c = [H⁺][S²⁻]/[HS⁻] = 1.0*10⁻¹⁹

H₂S(aq) <=> 2 H⁺(aq) + S²⁻(aq)

Kc = [H⁺]²[S²⁻] / [H₂S]

= [H+][HS⁻] / [H₂S] * [H⁺][S²⁻]/[HS⁻]

= K'c *K"c

= ( 9.5*10⁻⁸ ) * ( 1.0 x 10⁻¹⁹ )

= 9.5*10⁻²⁷

Hope this helps!

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