Electrochemical equivalent

Electrochemical equivalent

The electrochemical equivalent of a substance is a measure of the amount of that substance that is deposited or dissolved during electrolysis by the passage of a certain quantity of electric charge. It is typically expressed in terms of mass per unit charge, such as grams per coulomb (g/C).

Definition

The electrochemical equivalent (Z) can be defined by the equation: \[ Z = \frac{M}{nF} \] where:

• \( M \) is the molar mass of the substance,
• \( n \) is the number of electrons involved in the electrochemical reaction,
• \( F \) is the Faraday constant, approximately equal to 96485 C/mol.

Calculation

To calculate the electrochemical equivalent of a substance, one must know the molar mass of the substance and the number of electrons transferred in the reaction. For example, the electrochemical equivalent of silver (Ag) can be calculated as follows:

• Molar mass of Ag = 107.87 g/mol
• Number of electrons (n) = 1 (since Ag^+ + e^- → Ag)
• Faraday constant (F) = 96485 C/mol

Thus, the electrochemical equivalent of silver is: \[ Z_{Ag} = \frac{107.87 \text{ g/mol}}{1 \times 96485 \text{ C/mol}} \approx 0.001118 \text{ g/C} \]

Applications

The concept of electrochemical equivalent is crucial in various fields, including:

• Electroplating: Determining the amount of metal deposited on an object.
• Electrorefining: Purifying metals by electrolysis.
• Electrochemical cells: Calculating the efficiency and capacity of batteries.

Related Concepts

• Faraday's laws of electrolysis
• Electrolysis
• Electrochemical cell
• Electrode potential

See Also

• Faraday constant
• Electroplating
• Electrolysis
• Electrochemical cell
• Electrode potential