Question

What is the principle of electrochemical equivalent?

Answer 1

Could you clarify if you’re looking for a basic explanation, its applications, or perhaps its mathematical formulation?

Answer 2

The principle of **electrochemical equivalent** is based on **Faraday's laws of electrolysis**, which describe the relationship between the amount of substance produced at an electrode and the quantity of electric charge passed through an electrolyte. It helps determine the mass of a substance deposited or dissolved during an electrochemical reaction.

### **Faraday’s First Law of Electrolysis:**
It states that the mass of a substance (m) deposited or liberated at an electrode is directly proportional to the amount of electric charge (Q) passed through the electrolyte:
\[
m \propto Q
\]
\[
m = Z \cdot Q
\]
Where:
- \( m \) = mass of the substance deposited or dissolved (in grams)
- \( Q \) = electric charge passed (in coulombs)
- \( Z \) = electrochemical equivalent of the substance (in grams per coulomb)

### **Electrochemical Equivalent (Z):**
The **electrochemical equivalent** of a substance is the amount of substance deposited or dissolved by passing **one coulomb of electric charge** through an electrolyte. Its unit is grams per coulomb (g/C). The value of \( Z \) is related to the molar mass (M) and valence (n) of the ion being deposited by:
\[
Z = \frac{M}{n \cdot F}
\]
Where:
- \( M \) = molar mass of the substance (in grams per mole)
- \( n \) = valence (number of electrons involved in the reaction)
- \( F \) = Faraday constant (approximately 96,485 coulombs per mole)

### Example:
If a current is passed through a copper sulfate solution, copper ions (Cu²⁺) are deposited at the cathode. The electrochemical equivalent \( Z \) for copper can be calculated, and the mass of copper deposited is determined using the total charge passed through the solution.

In summary, the **principle of electrochemical equivalent** allows the calculation of how much material will be deposited or dissolved in an electrolytic process, based on the amount of charge and the properties of the substance.