What pressure (bar) of H2 would be required to make emf of hydrogen electrode zero in pure water at 25°C [2024]
(2)
2H+(aq)+2e-→H2(g)
By Nernst equation at 298K
EH+/H2=EH+/H2∘-0.059nlog10PH2[H+]2
For pure water [H+]=10-7 M and EH+/H2∘=0
0=0-0.0592log10PH2[10-7]2
log10PH2[10-7]2=0
PH2[10-7]2=1
PH2=10-14 bar