Represent symbolically the galvanic cells in which the following reaction occurs. Calculate the standard electromotive forces of the cells :
(3) `Zn+H_(2)SO_(4)rarr ZnSO_(4)+H_(2)`
Given : `E_(Fe^(2+)|Fe)^(@)=-0.44V, E_(Sn^(2+)|Zn)^(@)=-0.14V`,
`E_(Cu^(2+)|Cu)^(@)=0.34V, E_(Zn^(2+)|Zn)^(@)=-0.76V`,
`E_(H^(+)|(1)/(2)H_(2))^(@)=0.00V`.

Explanation

In the reaction, Zn(s) is oxidised to `Zn^(2+)`, and `H^(+)` ion is reduced to `H_(2)`. Thus, cathode is `H^(+)(aq)|H_(2)|Pt` and anode is `Zn|Zn^(2+)(aq)`.
Hence, the symbolic presentation of the cell is,
`Zn|Zn^(2+)(aq)||H^(+)(aq)|H_(2)" (g, 1 atm)"|Pt`
For the cell
`E_("cell")^(@)=E_("cathode")^(@)-E_("anode")^(@)=0-(-0.76V)=+0.76V`