Worked example

Ag+ +e−→Ag, 96500 C →107.9 g Ag.

Faraday’s Electrolysis

Mass deposited/evolved in electrolysis.

Equation

$m = \frac{Q M}{n F} = \frac{I t M}{n F}$

Inline: $m = \frac{Q M}{n F} = \frac{I t M}{n F}$$

Variables

Symbol	Quantity	Unit	Notes
$m$	mass	g	—
$Q$	charge	C	—
$I$	current	A	—
$t$	time	s	—
$M$	molar mass	g·mol⁻¹	—
$n$	electrons per ion	—	—

Conditions and limitations

Faradaic efficiency 100% assumed unless stated.

Rearrangements

$Q=m nF/M$

Dimensional check: C·g/mol / C/mol = g ✓

Worked example

Ag+ +e−→Ag, 96500 C →107.9 g Ag.

Steps: write equation → substitute with units → check dimensional consistency → report with correct significant figures.

Common errors

• Forgetting t unit seconds
• Using wrong n

Related resources

• redox-electrochemistry topic
• Calculators — linked only when a real calculator implements this formula.
• Constants — sourced constants with version when values are required.

Sources

• NIST Physical Constants 2022 — CODATA.

Reviewed 2026-08-21 by Editorial Team; due 2027-08-21.