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