Chemistry Unit 2 Electrochemistry HS 2nd year

 

Experiment 1: Construction and Working of a Daniell Cell

Objective:
To demonstrate the working of a galvanic cell using Zn and Cu electrodes and measure its emf.

Materials Required:

• Zinc rod

• Copper rod

• 1M ZnSO₄ solution

• 1M CuSO₄ solution

• Salt bridge (e.g., KCl in agar-agar)

• Voltmeter

• Wires and alligator clips

Procedure:

1. Prepare two half-cells: one with Zn rod in ZnSO₄ solution and the other with Cu rod in CuSO₄ solution.

2. Connect the two half-cells using the salt bridge.

3. Connect the zinc electrode to the negative terminal and copper to the positive terminal of the voltmeter using wires.

4. Record the emf of the cell.

Observation:
The voltmeter shows an emf around 1.1V.

Conclusion:
This cell converts chemical energy from the redox reaction into electrical energy.

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Experiment 2: Determination of Cell Potential Using Nernst Equation

Objective:
To determine the emf of a cell at non-standard conditions using the Nernst equation.

Reaction:
Zn(s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu(s)

Given:

• Standard emf (E°) = 1.10 V

• [Cu²⁺] = 0.1 M, [Zn²⁺] = 1.0 M

Procedure:

1. Use the Nernst equation:

   $$E_{cell} = E° - \frac{0.059}{2} \log\left(\frac{[Zn^{2+}]}{[Cu^{2+}]}\right)$$

2. Substitute the values into the formula.

3. Calculate the emf.

Calculation:

$$E_{cell} = 1.10 - \frac{0.059}{2} \log(10) = 1.10 - 0.0295 = 1.0705\ V$$

Conclusion:
The emf decreases when the concentration of Cu²⁺ decreases.

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Experiment 3: Determination of Conductivity of an Electrolytic Solution

Objective:
To measure the conductivity of a KCl solution using a conductivity meter.

Materials Required:

• Conductivity cell

• 0.1 M KCl solution

• Conductivity meter

• Thermometer

Procedure:

1. Calibrate the conductivity cell using standard KCl solution.

2. Rinse the conductivity cell and fill with the KCl solution.

3. Measure the resistance using the meter.

4. Calculate conductivity using:

   $$\kappa = \frac{G^*}{R}$$

   where $G^*$ is the cell constant.

Observation & Conclusion:
Conductivity value is recorded. It depends on ion concentration and temperature.

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Experiment 4: Electrolysis of Copper Sulphate Solution

Objective:
To demonstrate electrolysis using CuSO₄ solution and copper electrodes.

Materials Required:

• Copper electrodes

• 1M CuSO₄ solution

• DC power supply

• Beaker, connecting wires

Procedure:

1. Fill the beaker with CuSO₄ solution and insert copper electrodes.

2. Connect the electrodes to the power supply (cathode to negative terminal).

3. Pass current for a fixed time (e.g., 15 minutes).

4. Observe deposition at the cathode and dissolution at the anode.

Observation:
Copper is deposited on the cathode, and the anode dissolves.

Conclusion:
This demonstrates Faraday’s laws of electrolysis.