Electrochemical equivalent

Not to be confused with Equivalent (chemistry).

In chemistry, the electrochemical equivalent (Eq or Z) of a chemical element is the mass of that element (in grams) transported by a specific quantity of electricity, usually expressed in grams per coulomb of electric charge. The electrochemical equivalent of an element is measured with a voltameter.

Definition

The electrochemical equivalent of a substance is the mass of the substance deposited to one of the electrodes when a current of 1 ampere is passed for 1 second, i.e. a quantity of electricity of one coulomb is passed.

The formula for finding electrochemical equivalent is as follows:

$Z=M/q$

where $M$ is the mass of substance and $q$ is the charge passed. Since $q=It$, where $I$ is the current applied and $t$ is time, we also have

$Z=M/It$

Alternative formula for finding electrochemical equivalent is as follows:

$Z=E/F$

where $E$ is the Equivalent weight of the substance and $F$ is Faraday constant

Eq values of some elements in kg/C

Element	Electrochemical equivalent
Silver (Ag)	1.118×10^(-6) 0.000118gm/c
Copper (Cu)	3.295×10^(-7)
Gold (Au)	6.812×10^(-7)
Iron (Fe)	2.894×10^(-7)
Zinc (Zn)	3.389×10^(-7)
Hydrogen (H2)	1.044×10^(-7)
Sodium (Na)	2.387×10^(-7)
Potassium (K)	4.055×10^(-7)
Oxygen (O2)	8.28×10^(-8)
Aluminum (Al)	9.36×10^(-8)