The pressure of H2 required to make the potential of H2 electrode zero in pure water at 298 K is [2016]
10-10 atm
10-4 atm
10-14 atm
10-12 atm
(3)
pH = 7 for water.
-log[H+]=7 ⇒ [H+]=10-7
2H(aq)++2e- ⟶ H2(g)
Ecell=Ecell∘-0.05912logpH2[H+]2
0=0-0.05912logpH2(10-7)2
logpH2(10-7)2=0 ⇒ pH2(10-7)2=1 [∵log1=0]
pH2=10-14 atm