Faraday's Law Calculator Formula

Understand the math behind the faraday's law calculator. Each variable explained with a worked example.

Use the Faraday's Law Calculator

Formulas Used

Mass Deposited

mass = (current * time_s * molar_mass) / (z * 96485)

Total Charge

charge = current * time_s

Variables

VariableDescriptionDefault
currentCurrent (I)(A)5
time_sTime(s)3600
molar_massMolar Mass (M)(g/mol)63.55
zCharge Number (z)2

How It Works

Faraday's Law of Electrolysis

Formula

m = (I × t × M) / (z × F)

Where:

  • m = mass deposited (g)
  • I = current (A)
  • t = time (s)
  • M = molar mass (g/mol)
  • z = charge number (electrons per ion)
  • F = 96485 C/mol (Faraday's constant)

    • The mass deposited is proportional to the charge passed and the molar mass, and inversely proportional to the charge number.

    Worked Example

    Electroplating copper (M = 63.55, z = 2) with 5 A for 1 hour (3600 s).

    current = 5time_s = 3600molar_mass = 63.55z = 2
    1. 01m = (I × t × M) / (z × F)
    2. 02m = (5 × 3600 × 63.55) / (2 × 96485)
    3. 03m = 1,143,900 / 192,970
    4. 04m = 5.928 g

    Frequently Asked Questions

    What is Faraday's constant?

    Faraday's constant (F = 96485 C/mol) is the charge carried by one mole of electrons. It equals the Avogadro number times the elementary charge.

    What is the charge number z?

    z is the number of electrons transferred per ion. For Cu²⁺ → Cu, z = 2. For Ag⁺ → Ag, z = 1. For Al³⁺ → Al, z = 3.

    Can I calculate time needed for a given mass?

    Yes, rearrange to t = (m × z × F) / (I × M). This tells you how long to run electrolysis to deposit a target mass.

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