Mass Deposited in Electrolysis (Faraday's Laws) Calculator

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Overview

Faraday's Laws of Electrolysis provide a quantitative relationship between the amount of substance produced or consumed at an electrode during electrolysis and the quantity of electricity passed through the electrolyte. This equation, derived from Faraday's second law, allows for the calculation of the mass of a substance deposited or liberated, given the current, time, molar mass, number of electrons involved, and Faraday's constant. It is fundamental to understanding and predicting the outcomes of electrochemical processes.

Symbols

Variables

I = Current, t = Time, M = Molar Mass, n = Number of Electrons (n), F = Faraday Constant

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When To Use

When to use: This equation is applied when you need to calculate the mass of a substance produced or consumed during an electrolysis reaction. It can also be rearranged to find the current, time, molar mass, or the number of electrons transferred per mole of substance. Ensure all units are consistent, especially time in seconds and current in Amperes.

Why it matters: Faraday's Laws are crucial for industrial applications such as electroplating (e.g., chrome plating, silver plating), the refining of metals (e.g., copper, aluminum), and the production of elements like chlorine and sodium. It's also essential in battery technology, corrosion prevention, and in analytical techniques like coulometry, providing a quantitative basis for electrochemical engineering and research.

Avoid these traps

Common Mistakes

• Using time in minutes or hours instead of seconds.
• Incorrectly determining the value of 'n' (number of electrons) from the half-reaction.
• Using the atomic mass instead of the molar mass for diatomic elements (e.g., using 35.5 for Cl instead of 71.0 for $C{l}_2$).
• Errors in unit conversions, especially for current or time.

One free problem

Practice Problem

A current of $0.50\text{ A}$ is passed through a solution of $CuS{O}_4$ for $30\text{ minutes}$. Calculate the mass of copper deposited at the cathode. (Molar mass of Cu = $63.5\text{ g/mol}$).

Solve for: mass

Hint: Remember to convert time from minutes to seconds and determine the number of electrons (n) for copper deposition.

The full worked solution stays in the interactive walkthrough.

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Related Formulas

References

Sources

1. Atkins' Physical Chemistry
2. Bird, Stewart, and Lightfoot, Transport Phenomena
3. Wikipedia: Faraday's laws of electrolysis
4. IUPAC Gold Book: Faraday constant
5. NIST CODATA
6. IUPAC Gold Book
7. Britannica, The Editors of Encyclopaedia. 'Faraday's laws of electrolysis'. Encyclopedia Britannica, 22 Sep. 2023.
8. AQA A-level Chemistry — Physical Chemistry (3.1.10.3 Electrolysis)