General Chemistry Electrochemistry Math Question 6

Question

Compute the half-cell potential for reduction of aqueous hydronium ions to hydrogen gas at 0.5 bar and 25 C in buffer solution at pH = 2.87.

Answer 1

pH = 2.87

[H3O⁺] = 1x10^-2.87 = 1.35x10^-3 M

K = 0.5/(1.35x10^-3)²

K = 2.74x10⁵

E = Eº - 0.059/2 log K = 0 - 0.0295 log 2.74x10⁵

E = -0.0295 x 5.44

E = -0.16V