Equivalent Weight
The mass of a substance that combines with or displaces 1.008 g of hydrogen, 8 g of oxygen or one mole of electrons.
Formula / equation
E = M / n-factor
Unit
g/equiv
In depth
The n-factor is the valency for an element, the number of replaceable protons for an acid, the number of hydroxide ions for a base, or the electrons transferred for a redox species. Equivalent weight underlies normality and simplifies volumetric calculations, though molarity has largely replaced it.
Examples in the real world
H₂SO₄ has equivalent weight 98/2 = 49 g; KMnO₄ in acid is 158/5 = 31.6 g.