The reaction of tin metal with acid can be written as
`Sn(s) + 2H^(+) (aq) rarr Sn^(2+) (aq) + H_(2)(g), E _(Sn^(2+)//Sn)^(@) =-0.14 V`
Assume that `[Sn^(2+)]`=1 M and the partial pressure of hydrogen gas is 1 atm, then the

Options

A. cell reaction is spontaneous at pH = 5
B. cell reaction is non-spontaneous at standard conditions
C. cell reaction is spontaneous at pH = 2
D. cell reaction is spontaneous for all pH values

Answer

C

Explanation

`Sn(s)+2H^(+)(aq) rarrSn^(2+)(aq)+H_(2)(g)`
Nernst equation for this cell reaction is `E_(cell) =E_(cell)^(@)-(RT)/(nF)`
For standart state `E_(Cell)=E_(cell)^(@)=0.14 V`
For `pH =2E_(cell)=0.14 (0.059)/(2)log (1)/(10^(-2))=0.14 -0.12 =0.02v`