There are certain modifications required in order to use law of equivalence. These modifications are

• The equivalents of a substance produced and reacted may not necessarily be same. If the n-factor of the substance, in the reaction in which it is produced were different than the n-factor of the same substance, when it is reacting, then the equivalent of the substance produced and reacted would be different.

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  • The equivalents of the same substances can be added or subtracted only when they are of the similar n-factor.

  • In a reaction, the equivalents of oxidizing agents would always be equal to the equivalents of reducing agents, irrespective of the number of agents used in the reaction.