# Chemistry (NMK)

Eqv. Mass of A = Mass of A

Eqv. Mass of B         Mass of B

à This relation tells that the combining mass reactants is always in the ratio of their equivalent mass. This law is also known as LAW OF CHEMICAL EQUIVALENCE.

@ Atomic Mass = Eqv. Mass X Valency

@ ‘Gram Eqv.’ or ‘Eqv.’

à Eqv. mass of a substance, expressed in gram is ‘one gram equivalent’ or ‘1 eqv.’

Equivalent Mass of a compound

a) Eqv. mass of acid
= Molecular Mass of acid
Basicity
where Basicity of an acid is defined as no. of H+ ions displaced or OH- ions combined per molecule of the acid.
Eqv. mass of H2SO4 = 98 / 2 = 49
b) Eqv. mass of Base
= Molecular Mass
Acidity
where acidity of the base is defined as the no. of H+ ions consumed or OH- ions displaced per molecule of the base.
Eg.
Eq. Mass of Ca(OH)2 = 74/2 = 37

c) Eqv. mass of Salt
Molecular Mass of Salt
Total no. of charge in basic or acid radical per molecule
Eg.
Eq. mass of Na2CO3 =  106 / 2  =  53

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