The pressure of `H_(2)` required to make the potential of `H_(2)` - electrode zero in pure water at 298 K is -

Options

A. `10^(-10)atm`
B. `10^(-4)atm`
C. `10^(-14)atm`
D. `10^(-12)atm`

Answer

C

Explanation

`2H^(+)(aq)+2e rarr H_(2)(g)`
`E=E^(0)-(0.059)/(2)log.(p_(H_(2)))/([H^(+)(aq)]^(2))`
`=0-(0.059)/(2)log.(p_(H_(2)))/([10^(-7)]^(2))=-(0.059)/(2)log(p_(H_(2))xx10^(14))`
`0=-(0.059)/(2)log(p_(H_(2))xx10^(14))`
`therefore p_(H_(2))=10^(-14)`