Question

Potential of H2 gas electrode set up in an acid solution of unknown strength is
0.0295 V at 250C when coupled with SHE. Find the pH of the acid solution?

Answer 1

Answer:

The both electrode are same thus there straight E subscript cell superscript 0 =0

Since the potential of the hydrogen electrode measured against standard hydrogen electrode is a positive value, the electrode is acting as the anode. If the unknown [H+] be x, the Nernst equation takes the form

straight E subscript cell space equals space straight E degree subscript cell minus fraction numerator 0.0592 over denominator 2 end fraction log straight x squared over 1 squared

Since both electrodes are the same, straight E degree subscript cell space equals space 0.

∴ 0.29 space straight V space equals space 0 minus fraction numerator 0.0592 space straight V over denominator 2 end fraction cross times space 2 space log space straight x

or 0.29 straight V space equals space minus 0.0592 space straight V space cross times space log space straight x

Since negative logx space equals space minus log open square brackets straight H to the power of plus close square brackets space equals space pH

0.029 space straight V space equals space 0.0592 space straight V space cross times space pH

or pH space equals space fraction numerator 0.29 over denominator 0.0592 end fraction equals 4.9.