Equivalent mass of a substance may be calculated as,
Equivalent mass`=("Molecular mass")/("n-factor")=("Atomic mass")/(n-factor")`
n-factor= Basicity of acid or acidity of base
n-factor= Number of moles of electrons gainted or lost per mole of oxidising or reducing agents
n-factor= Total positive or negative valency of a salt
n-factor= Valency of an ion.
Concept of n-factor is very important for redox as well as for non-redox reactions.
Equivalent mass of ferrous oxalate `FeC_(2)O_(4)` in the following reaction is :
`FeC_(2)O_(4) to Fe^(3+) + 2CO_(2)`