For the cell (at 1bar `H_(2)` pressure) Pt|`H_(2)`(g) HX(m_(1), NaX(m_(2), NaCl(m_(3)|AgCl|Ag|Pt is found that the value of `E-E^(@) + RTF^(-1)` in `[(m_(HX).mCl^(-))/(m_(X^(-)))]` approaches 0.2814 in the limit of zero concentration. Calcualte `K_(a)` for the acid HX at `25^(@)C` expressing your answer as `10^(7)`K_(a)`

Answer

174

Explanation

`E=E^(@)+RTF^(-1)ln([X^(-)])/(K_(a)[HX][Cl^(-)])impliesE-E^(@)+RTF^(-1)ln([HX][Cl^(-)])/([X^(-)])RTF^(-)ln(1)/(K_(a))`
`impliesl n(1)/(K_(a))=(96500)/(8.315xx298)(0.2814)impliesK_(a)=1.74xx10^(-5)`