1. Faraday’s First Law of electrolysis: Mass \(m\) of electrochemically-transformed substance is proportional to the charge \(Q\) passed, \(m\! \propto\! Q\).
2. Faraday’s Second Law of electrolysis: When the same electric charge (quantity of electricity) \(Q\) is passed through several electrolytes, the mass \(m_{\rm{i}}\) of the substances deposited are proportional to their respective chemical equivalent molar mass, \(M_{\rm{i}}/z_{\rm{i}}\). \[m_{1}/m_{2} = (M_{1}/z_{1})/(M_{2}/z_{2})\]

Notes:

1. The relationship may be formulated as \(m=MQ/zF\), where \(M\) is the molar mass of the substance, \(z\) the number of electrons transferred (see: electron number of an electrochemical reaction), and \(F\) is the Faraday constant.
2. Measurement of charge using a coulometer relies on Faraday’s Law.
3. If reference is made only to ‘Faraday’s Law of electrolysis’ the first law is meant.