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Electrolysis Calculator – Mass, Time, Current & Charge

Calculate deposited mass, required time, current, or electric charge in electrolysis using Faraday's law. Supports copper, silver, hydrogen, and custom substances.

932.7K usesUpdated · 2026-04-25Runs locally · zero upload

How to Use

  1. Select what to solve for from the four options: Deposited Mass, Required Time, Required Current, or Electric Charge.
  2. Choose a substance preset (e.g., Cu, Ag, H₂) or select Custom and enter the molar mass (g/mol) and electron transfer number (n) manually.
  3. Enter the known values — current (A), time with unit selector (s/min/h), or target mass depending on the mode.
  4. Results appear automatically on the right panel, showing the primary result alongside moles produced and electric charge.

A formula reference box at the bottom shows the core formula at a glance.

Formula & Theory

Electrolysis calculations are governed by Faraday's Laws of Electrolysis. The key formula relating mass deposited to electrical charge is:

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

Where:

  • $m$ = mass of substance deposited or liberated (g)
  • $I$ = current (A, amperes)
  • $t$ = time (s, seconds)
  • $M$ = molar mass of the substance (g/mol)
  • $n$ = number of moles of electrons transferred per mole of substance
  • $F$ = Faraday's constant ≈ 96,485 C/mol

The electric charge passed is simply: $$Q = I \cdot t \quad \text{(Coulombs)}$$

The moles of substance deposited: $$\text{moles} = \frac{Q}{n \cdot F} = \frac{m}{M}$$

The calculator supports four calculation modes derived from the same formula:

  • Mass (given I, t, M, n) → $m$
  • Time (given m, I, M, n) → $t = \frac{m \cdot n \cdot F}{I \cdot M}$
  • Current (given m, t, M, n) → $I = \frac{m \cdot n \cdot F}{t \cdot M}$
  • Charge (given I, t) → $Q = I \cdot t$

Use Cases

  • Electroplating industry: Calculate how long to plate a copper coating of a specific thickness (mass) onto a metal part at a given current.
  • Chemistry students: Solve Faraday's law problems for exams covering electrochemistry.
  • Research labs: Determine the current required to deposit a precise amount of metal in experimental setups.
  • Battery and fuel cell engineers: Estimate theoretical charge capacity and mass changes during charge/discharge cycles.
  • Water electrolysis (hydrogen production): Calculate how much hydrogen gas is produced per unit of time at a given current.

Frequently asked questions about Electrolysis Calculator – Mass, Time, Current & Charge

What is Faraday's constant and why is it used?

Faraday's constant (F ≈ 96,485 C/mol) is the electric charge of one mole of electrons. It links the amount of electric charge passed through an electrolyte to the amount of substance deposited or liberated at the electrode.

Can I calculate how long it takes to deposit a specific mass?

Yes. Select 'Required Time (t)' in the Solve For section, enter the target mass, current, molar mass, and electron count. The calculator will output the required time in both seconds and minutes.

What does 'electrons transferred' (n) mean?

It is the number of moles of electrons transferred per mole of substance. For copper (Cu²⁺ + 2e⁻ → Cu), n = 2. For silver (Ag⁺ + e⁻ → Ag), n = 1.

How do I enter a custom substance?

Select 'Custom' from the substance preset list, then manually type the molar mass (g/mol) and the electron transfer number into the input fields.

Is my data stored or sent to a server?

No. All calculations are performed entirely in your browser. No input data is transmitted or stored.