Practical No. 07: Electrochemical Equivalent of Copper using Faraday’s First Law
XIII. Interpretation of Results
Electrolysis of CuSO₄ deposited copper on cathode. Weight deposited was directly proportional to quantity of electricity passed, confirming Faraday’s first law. Electrochemical equivalent of copper was close to theoretical value of 0.000329 g/C.
XIV. Conclusions and Recommendations
- Conclusion: Weight of substance deposited is directly proportional to quantity of electricity passed.
- Recommendation: Clean cathode thoroughly, maintain constant current, and accurately record time for precise results.
XV. Practical Related Questions & Answers
Q1. Describe the relation between chemical equivalence and electrochemical equivalence.
- Answer: Chemical equivalence refers to the equivalent weight of a substance (atomic weight / valency). Electrochemical equivalent is the weight of substance deposited by 1 coulomb of electricity. They are related by Faraday’s laws: Electrochemical equivalent (Z) = Equivalent weight / 96500. Thus, electrochemical equivalent is directly proportional to chemical equivalent.
Q2. State the relation between the Time for which Current is passed through solution and weight of the substance deposited on electrode.
- Answer: According to Faraday’s first law, the weight of substance deposited (W) is directly proportional to the time (t) for which current is passed, provided current (I) is constant. W ∝ t, or W = Z × I × t, where Z is electrochemical equivalent. Thus, longer time results in greater deposition of substance.
Q3. Identify the electrode type formed by the copper anode.
- Answer: The copper anode is a consumable/sacrificial anode in this electrolysis process. As current passes, the copper anode dissolves into Cu²⁺ ions, which migrate to the cathode where they get deposited. The anode loses mass, and this type of anode is called a “soluble anode.”
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