Question

How to find out electrochemical equivalents?

Answer 1

To find the electrochemical equivalent of a substance, you need to use the relationship between the amount of substance that undergoes electrolysis and the amount of electric charge passed through the electrolyte. The electrochemical equivalent (denoted as \(Z\)) is a constant that gives the mass of a substance deposited or dissolved when a certain amount of charge passes through the electrolyte.

Formula to calculate Electrochemical Equivalent:

The electrochemical equivalent \(Z\) is given by:

\[
Z = \frac{M}{nF}
\]

Where:

1. \(M\) = Molar mass of the substance (in grams per mole, g/mol)
   

1. \(n\) = Number of electrons involved in the electrochemical reaction (the valency of the substance)
   

1. \(F\) = Faraday’s constant (\(F = 96,485 \, \text{C/mol}\))
   

Steps to Find Electrochemical Equivalent:

1. Determine the molar mass \(M\) of the substance you are studying.
   

   - For example, for copper (Cu), the molar mass is 63.5 g/mol.

1. Find the number of electrons \(n\) involved in the electrochemical reaction.
   

   - For copper, during the deposition reaction, \(n = 2\) electrons are involved (because Cu\(^{2+}\) gains 2 electrons to become Cu).

1. Use Faraday’s constant \(F = 96,485 \, \text{C/mol}\).
   

1. Plug the values into the formula to calculate the electrochemical equivalent.
   

Example for Copper:

For copper (Cu) undergoing deposition:

1. Molar mass \(M = 63.5 \, \text{g/mol}\)
   

1. Number of electrons \(n = 2\)
   

1. Faraday constant \(F = 96,485 \, \text{C/mol}\)
   

\[
Z = \frac{63.5}{2 \times 96,485} \approx 0.000329 \, \text{g/C}
\]

So, the electrochemical equivalent for copper is 0.000329 g/C. This means that for each coulomb of charge passed through the electrolyte, 0.000329 grams of copper will be deposited.

Summary:

1. Electrochemical equivalent relates the mass of a substance deposited or dissolved in electrolysis to the amount of charge passed through the solution.
   

1. The formula to calculate it involves the molar mass of the substance, the number of electrons involved in the reaction, and Faraday’s constant.
   

This is the basic approach to calculating electrochemical equivalents!