Equivalent mass of a reducing agent

Equivalent weight of reducing agent is the number of parts by mass of it, which can be oxidized by 8 parts by mass of oxygen. 

Indicators

Indicators are substances which change colour at the end point and indicate the completion of the reaction.

Equivalent weight of an Oxidizing agent

It is the number of parts by weight of it which furnishes one equivalent of oxygen (8 parts by weight) for the purpose of oxidation. 

Law of Equivalents

One equivalent of one substance reacts with one equivalent of the other.

Equivalent Weight of an Salt

It is defined as the number of parts by weight of it that contains one equivalent of the metal.

Equivalent Weight of a base

It is defined as the number of parts by weight of  it that contains one equivalent of the metal. 

Equivalent Weight of an Acid

It is defined as the number of parts by weight of the acid containing 1.008 parts by weight of replaceable hydrogen. 

Equivalent Weight of an Element

It is defined as the number which denotes the number of parts by weight of an element required to combine with or displace 8 parts by weight of oxygen, 1.008 parts by weight of hydrogen and 35.5 parts by weight of chlorine.