Question

The emf of the cells obtained by combining zinc and copper electrodes of the Daniell cell with calomel electrodes are $1.083volt$ and $-0.018volt$ respectively at $25{}^{\circ }C$. If the reduction potential of normal calomel electrode is $+0.28$ volt, find he emf of the Daniell cell.

Answer 1

For the cell $Zn$ electrode $\parallel$ Calomel electrode
$E_{cell}=$ Oxide. pot. of $Zn$ electrode $+$ Red. pot. of calomel electrode
So, oxid. pot. of $Zn$ electrode $=1.083-0.28=0.803volt$
For the cell,
$Cu$ electrode $\parallel$ Calomel electrode
$E_{cell}=$ Oxid. pot. of $Cu$ electrode $+$ Red. pot. of calomel electrode
So, oxid. pot. of $Cu$ electrode $=-0.018-0.28=-0.298$
For the Daniell cell,
$Zn$ electrode $\parallel Cu$ electrode
$E_{cell}=$ Oxid. pot. of $Znelectrode+$ Red. pot. of copper electrode$
$=0.803+0.298=1.101volt$.