What is meant by electrochemical equivalent of a substance?

Explanation

**Step-by-Step Text Solution:**

1. **Definition of Electrochemical Equivalent**: The electrochemical equivalent (Z) of a substance is defined as the mass of the substance that is deposited or liberated at an electrode during electrolysis when one equivalent of electric charge passes through the electrolyte.

2. **Faraday's Law of Electrolysis**: According to Faraday's laws of electrolysis, the mass (m) of a substance deposited or liberated at an electrode is directly proportional to the quantity of electric charge (Q) that passes through the electrolyte. This can be expressed mathematically as:
\[ m \propto Q \]
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