Question

Difference between primary standard and secondary standard

Answer 1

Standard in laboratory means acids, bases, oxidants or reductants, especially in titration. A primary standard is that which does not decompose on it's own at laboratory tempreture. If a compound readily undergoes decomposition readily under laboratory condition, then its purity is lost. It invariably accompanies impurity. Hence it does not help precisely to calculate the strength of other with which it is titrated for the purpose of determination of strength.

For example; Potassium Permanganate is an excellent oxidants against many reductants. Still it's not used as titrant to calculate the strength of a reductant. Because, Potassium Permanganate readily undergoes decomposition at all conditions of temperature and pressure, hence it is not used as a primary standard in laboratory.