(N/A) $(i)$ Cell Potential: The potential difference between the two electrodes of a galvanic cell is called the cell potential and is measured in volts.
$(ii)$ $emf$: The cell potential is the difference between the electrode potentials (reduction potentials) of the cathode and anode. It is called the cell electromotive force $(emf)$ of the cell when no current is drawn through the cell.
$(B)$ Formula and expression of cell potential:
Cell potential of a galvanic cell is positive,which can be calculated by the following formula:
$E_{cell} = E_{right} - E_{left} = E_{red(cathode)} - E_{red(anode)}$
The anode is on the left and the cathode is on the right while representing the galvanic cell. $A$ galvanic cell is generally represented by putting a vertical line between metal and electrolyte solution and putting a double vertical line between the two electrolytes connected by a salt bridge.
| Anode half cell | Salt bridge | Cathode half cell |
|---|
| Metal of anode electrode | The product of oxidation of anode | Whose reduction is electrolyte | The product produced from reduction (metal) |
$(C)$ Expression of Daniell cell:
Example: $Zn_{(s)} | Zn_{(aq)}^{2+} || Cu_{(aq)}^{2+} | Cu_{(s)}$
Oxidation on anode: $Zn_{(s)} \longrightarrow Zn_{(aq)}^{2+} + 2e^{-}$
Reduction on cathode: $Cu_{(aq)}^{2+} + 2e^{-} \longrightarrow Cu_{(s)}$
Total cell reaction: $Zn_{(s)} + Cu_{(aq)}^{2+} \longrightarrow Zn_{(aq)}^{2+} + Cu_{(s)}$
Where,$Zn$ electrode is the anode and copper electrode is the cathode.
Daniell cell potential:
$E_{cell} = E_{right} - E_{left}$
$E_{cell} = E_{Cu^{2+}|Cu} - E_{Zn^{2+}|Zn}$