I 2 ( s ) / I - (0.1 M) half cell is connected to a H + ( a q ) / H 2 (1 bar)/Pt half cell and e.m.f. is found to be 0.7714 V. If E I 2 / I - o = 0.535 V , find the pH of H + / H 2 half cell.

Step-by-step solution

The cell reaction is H 2 ( g ) + I 2 ( s ) ⇌ 2 H ( a q ) + + 2 I ( a q ) - Here n = 2 (n = number of electons involved ) E = E ° - 0.0591 n l o g [ H + ] 2 [ I - ] 2 P H 2 0.7714 = 0.535 - 0.0591 2 l o g [ H + ] 2 [ 0.1 ] 2 1 On solving ( H + ) = 1 0 - 3 p H = - l o g ( H + ) = - l o g ( 1 0 - 3 ) So p H = 3