Do I need the molar mass?

Only if you want mass in grams. If you just need moles, you can omit the molar mass.

How do I include current efficiency?

Enter a percentage (e.g., 95). The effective charge is Q×(η/100), which reduces the calculated moles and mass accordingly.

All calculators

Electrolysis Calculator

Q: What value should I use for n?

Use the number of electrons per mole of product. For example, Ag+ → Ag: n=1; Cu2+ → Cu: n=2; 2H+ → H2: n=2.

Estimate the amount of substance deposited or dissolved during electrolysis using current, time, and the number of electrons transferred (n). Uses Faraday’s law: Q = I·t and moles = Q / (n·F).

Background

Faraday’s constant F = 96485 C·mol⁻¹. Given a current I and time t, the charge passed is Q = I·t. If n electrons are required per mole of product, then moles(product) = Q / (n·F) and mass = moles·M (where M is molar mass). You can optionally include current efficiency (%).

Enter values to compute deposited/dissolved amount:

Current (I):

Units: A mA

Time (t):

Units: s min h

Electrons per mole (n):

Molar Mass (M) in g/mol (optional but needed for mass):

Current Efficiency (%) (optional, default 100):

Molar Gas Volume (L/mol) (optional, for gas products):

If provided, the calculator will also report gas volume = moles × molar gas volume.

Quick examples:

Result:

No results yet. Enter values and click Calculate.

How to use this calculator

1) Enter current, time, n, and (optionally) molar mass and efficiency.
2) Click Calculate to get charge, moles of product, and mass.
3) If generating a gas, add a molar gas volume (e.g., 22.414 L/mol at STP) to get volume.

Tips

Common n values: Ag⁺→Ag: 1; Cu²⁺→Cu: 2; Al³⁺→Al: 3; 2H⁺→H₂: 2; 2Cl⁻→Cl₂: 2.
If efficiency < 100%, only a fraction of the charge plates the target species.
Units convert automatically (A↔mA, s/min/h).

Formulas Used

Charge passed: Q = I·t (C).
Effective charge (with efficiency η%): Q_eff = Q × (η/100).
Moles of electrons: n_e⁻ = Q_eff / F.
Moles of product: n_product = n_e⁻ / n.
Mass: m = n_product·M.

Example Problems & Step-by-Step Solutions

Example 1: Mass from current & time (Cu²⁺ → Cu)

I = 2.50 A, t = 30.0 min (1800 s), n = 2, M = 63.546 g/mol, F = 96485 C/mol.
Q = 2.50×1800 = 4500 C; moles e⁻ = 4500/96485 = 0.04664 mol e⁻;
moles Cu = 0.04664/2 = 0.02332 mol; mass = 0.02332×63.546 ≈ 1.48 g.

Example 2: Gas volume (2H⁺ → H₂ at STP)

I = 1.20 A, t = 40.0 min (2400 s), n = 2; Vm = 22.414 L/mol (STP).
Q = 1.20×2400 = 2880 C; moles e⁻ = 2880/96485 = 0.02985 mol e⁻;
moles H₂ = 0.02985/2 = 0.01493 mol; volume = 0.01493×22.414 ≈ 0.334 L.

Frequently Asked Questions

Q: What value should I use for n?

Use the electrons per mole of product. For example, Cu²⁺→Cu needs 2 e⁻ per Cu atom (n=2).

Q: Do I need molar mass?

Only if you want mass (grams). If you just need moles, you can leave M blank.

Q: How do I include efficiency?

Enter a percentage. If 100%, all charge goes to your target species; if 90%, only 90% does.

Standard Reduction Potentials