A Daniell Cell is an electrochemical cell that converts chemical energy into electrical energy through a spontaneous redox reaction. It is also referred as a galvanic or voltaic cell. It consists of two half-cells that are connected by a salt bridge to maintain electrical neutrality through the flow of ions. The first half-cell consists of a Zn rod dipped in a ZnSO4 solution, while the other half-cell consists of a Cu rod immersed in a CuSO4 solution. The two rods are connected by a wire to complete the circuit through which the electron flows, and a voltmeter may be connected in the circuit to measure the electrode potential. If the circuit in a Daniell cell represented by the cell notation, Zn | Zn2+ || Cu2+ | Cu, is closed, then it is observed that as time passes the concentration of Zn2+ keeps on increasing, while the concentration of Cu2+ keeps on decreasing. At the same time, the voltage of the cell as read on the voltmeter keeps on decreasing. After some time, the voltmeter shows zero reading.
If the standard electrode potential of Zn2+/Zn = −0.76 V and the standard electrode potential of Cu2+/Cu = 0.34 V, then the standard electrode potential for the Daniell cell is
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 1.10 V
Standard electrode potentials are tabulated as reduction potentials. The standard emf of a cell is the reduction potential of the cathode (right side) minus that of the anode (left side):
\( \displaystyle E^{\circ}_{cell}=E^{\circ}_{\text{cathode}}-E^{\circ}_{\text{anode}}=E^{\circ}_{\text{right}}-E^{\circ}_{\text{left}} \)
In the Daniell cell, copper is the cathode and zinc is the anode:
\( \displaystyle E^{\circ}_{cell}=E^{\circ}_{\ce{Cu^2+/Cu}}-E^{\circ}_{\ce{Zn^2+/Zn}} \)
\( \displaystyle E^{\circ}_{cell}=0.34-(-0.76)=+1.10\ \mathrm{V} \)
So the standard potential of the Daniell cell is 1.10 V. A positive value confirms that the cell reaction is spontaneous.
Note: This question is from NCERT (2026-27). NTA sets numerical questions from NCERT too, so do not ignore NCERT while practising numericals.
NCERT (2026-27 edition):
Measurement of Electrode Potential – …
