Equivalent weight

Equivalent weight (also known as gram equivalent) is a term which has been used in several contexts in chemistry. In its most general usage, it is the mass of one equivalent, that is the mass of a given substance which will

• combine or displace directly or indirectly with 1.008 parts by mass of hydrogen or 8 parts by mass of oxygen or 35.5 parts by mass of chlorine; or
• supply or react with one mole of hydrogen cations  in an acid–base reaction; or
• supply or react with one mole of electrons (e^-) in a redox reaction.