Question

What would the potential of a standard hydrogen (S.H.E.) electrode be if it was under the following conditions?

[H+]=0.59M   P_H2 =3.0 atm T=298 K

Answer 1

The half reaction for Hydrogen electrode is 2 H⁺ + e^- H₂ (g)

We know that the potential under standard conditions is 0V ---> E^o = 0V

According to Nernst Equation ,     at 298 K

Given [H⁺] = 0.59M

         p_H2 = 3.0 atm

Conversion of pressure units to concentration :

We know that P = CRT

                     C = P / RT                  P = pressure = 3.0 atm

                                                       R = gas constant =0.0821 L atm /mol-K

                                                      T = temperature = 298 K

                    C = 3.0 / ( 0.0821 x 298 )

                       = 0.123 M

Plug the values we get