Question

What is the difference between pure and impure hydrogen?

Answer 1

Pure and Impure Substances - All matter can be broadly divided into two major groups "Pure" and "Impure". The term 'purity' has quite a different meaning in chemistry than in our day-to-day life. Normally when we refer to pure water 

A Pure substance is composed of the same kind of particles." 

a) A pure substance is homogeneous, irrespective of its origin or method of preparation, and it consists of only one kind of particles e.g. hydrogen, oxygen, water, sodium chloride, etc. 

b) A pure substance has definite properties, characteristic of itself. 

c) A pure substance has the same composition throughout. For e.g., different samples of water, prepared by different methods, by different people at different places always consist of hydrogen and oxygen in the ratio 1:8 by mass and 2:1 by volume. If any sample has a different ratio of these elements, then it certainly is not water. 

Remember:- 

A solution of salt in water or sugar solution being homogeneous appears to consist of one type of particles. But it is made up of more than one kind of particles. Hence it is not a pure substance. It is a mixture.

Answer 2

when a lit matchstick is brought near a jar of pure hydrogen it burns with pop sound and extinguishes pure hydrogen burns silently with blue flame to produce water.

Impure hydrogen when mixed with air burns slightly with blue flame the produced water will be impure