24.1.4—Determination of a value of the Avogadro

An electrolytic determination measures current and time, finds the amount of substance liberated from a known half-equation, and relates charge per mole of electrons to the number of electrons and elementary charge.

Measure mass or gas volume accurately, convert to moles, use the electron ratio, and calculate F = Q/n(e⁻). Dividing F by e gives L.

If a silver cathode gains mass corresponding to 0.0100 mol Ag⁺ after 965 C, then 0.0100 mol e⁻ passed and F≈96,500 C mol⁻¹; with e known, L follows.

The measured substance amount is not automatically the electron amount; use the electrode half-equation and account for side reactions.