Write the Nernst equation and calculate the e.m.f. of the following cell at 298K.
`Sn_((s))|Sn_((0.050M))^(2+)||H^(+)(0.020M)|H_(2)(1atm//Pt)`
Given `E_(Sn//Sn^(2+))^(@)=-0.14V`
`EMF=(E_(H^(+)//1//2H_(2))^(@)-E_(Sn^(2+)//Sn)^(@))-(0.0591V)/(2)"log"([Sn^(2+)])/([H^(+)]^(2))`.

Explanation

`Sn(s)|Sn^(2+)(0.050M)||H^(+)(0.020M)|H_(2)(atm)Pt`.
Oxidation: `Sn to Sn^(2+)+2e^(-)`
Reduction: `2H^(+)+2e^(-) to H_(2)`
Overall: `2H^(+)+Sn to Sn^(2+)+H_(2)`
Here, n=2