A cell raction is `n (s)| Sn_((0.50M))^(2+)//H_((0.020M))^(+)//H_(2)(g)`. Calculate `E_("cell")` of a reaction and also write Nernst equation.
Given: `E^(@)(sin^(2+)|Sn)= -0.14V and E^(@)(H^(1+)|H)= 0.00V`

Explanation

`"Oxd"^(n)` half cell reaction : `Sn_((s)) + Sn_((aq))^(2+) + 2e^(-)`
`"red"^(n)` half cell reaction: `[H_((aq))^(+) + e^(-) rarr H_(2(g))] xx 2`
Overall reaction: `Sn_((s)) + 2H^(+) (aq) rarr Sn_((aq))^(2+) + H_(2)(g)`
Nernst equation `E_("cell") = E_((H^(+)|H))^(@)- E_((Sn^(2+)|Sn))^(@) - (0.059)/(2) "log" ([Sn^(2+)])/([H^(+)])^(2)`
`=0.0 + 0.14- (0.059)/(2) "log" ((0.050))/((0.020)^(2))`
`=0.14 - (0.059)/(2) log 125`
`=0.14 - (0.059)/(2) xx 2.099 = 0.14 - 0.06 = 0.08V`