Hydrogen sulfide will react with water as shown in the following reactions.?

Question

H2S(g) + H2O(l) = H3O+(aq) + HS-(aq); K1 = 1.0 ´ 10-7

HS-(aq) + H2O(l) = H3O+(aq) + S2-(aq); K2 = ?

H2S(g) + 2H2O(l) = 2H3O+(aq) + S2-(aq); K3 = 1.3 ´ 10-20

* = equlibrium

What is the value of K2?

A. 1.3 x 10-27

B. 2.3 x 10-7

C. 1.3 x 10-13

D. 7.7 x 1012

E. 7.7 x 1026

Answer 1

The steps of reactions :

HS- + H3O+ --> H2S + H2O   K1= 1/10-7

H2S + 2H2O --> 2H3O+ + S2-   K3= 1.3 x 10-20

--------------------------

HS- + H2O --> H3O + S2-   K2= 1/K1 x K3

K2 = 1/10-7 x 1.3 x 10-20

= 1.3 x 10-13

The answer is C.