Emf By Daniel Cell 6f3n67

EMF by Daniell cell AIM: To calculate EMF of Daniell cell (Zn-Cu couple) PRINCIPLE: Daniell cell is the simplest voltaic or galvanic cell. It converts chemical energy into electrical energy spontaneously. The principle behind Daniel cell is redox reaction.

Zn (s) | Zn+2 (1 M) || Cu+2 (1 M) | Cu (s)

In this process, Zn electrode dissolves in the solution of ZnSO4 and reduces in size while Cu electrode grows in size due to the deposition of copper metal. Daniell cell generates an electric potential of 1.10 volt, when the solutions in the half cells are both 1M (standard condition) Under nonstandard conditions (when concentration of solutions is away from 1M), the potential of the

cell can be calculated by Nernst equation:

E = E0 − 0.0592 log [ Zn+2] n [Cu+2]

E0 = 1.1 V, n=2

RECTIONS: At the anode: Zn/ ZnSO4

Oxidation ---------------- loss of electrons.

At cathode: Cu/ CuSO4 Reduction -------------gain of electrons.

The total reaction is the sum of two half-cell reactions. Zn(s) + Cu2+(aq)

Zn2+(aq) + Cu(s)

REQUIRED REAGENTS & EQUIPMENTS: 1M CuSO4, 1M ZnSO4, salt bridge, voltmeter, Zn and Cu electrodes, pipettes, volumetric flasks, beakers, distilled water PROCEDURE: 1. Prepare 0.1, 0.01, 0.001 molar CuSO4 solutions from the stock (1M) by serial dilutions.

2. Calculate the emf values for the concentrations in the table by using Nernst

equation 3. Experimentally determine the emf values of the Daniell cell set up for the concentrations in the table as per the assembly shown in diagram

OBSERVATION: Conc. ZnSO4

Conc. CuSO4

EMF Theoretical value

1 M/ 0.1 M

1 M/ 0.1 M

1.10 V

1

0.1

1

0.01

1

0.001

CALCULATIONS: E = E0 − 0.0592 log [ Zn+2] n [Cu+2]

E0 = 1.1 V, n=2

EMF Actual value

RESULT: The EMF of the Daniell cell was calculated and it was found that it decreases with decreasing concentration of the cathodic solution