Question

Describe simple experiments to show the presence of -

oxygen and nitrogen component in air using a bell jar

Answer 1

Oxygen and nitrogen in air:

Apparatus— A through, a bell jar, a cork and a crucible and a piece of white phosphorus.

producer-

1. The trough is filled with water and a bell jar divided into 5 equal parts, ‘1 to 5’ is placed over it.
2. A crucible containing white phosphorus is placed on a cork which is made to float on water.
3. The level of the water inside and outside are adjusted to one level.
4. The phosphorus is then ignited by means of a heated wire.

Observation-

1. The phosphorus burns in the active component of air [oxygen] forming – dense white fumes of phosphorus pentoxide [P₂O5]. Phosphorus + Oxygen →Phosphorus pentoxide
2. The level of the water in the bell jar rises by l/5th.

Conclusion-

1. Oxygen— The active component of air, i.e. 1/5th of air, is used up in burning.
2. Nitrogen— The inactive component of air, i.e. 4/ 5 of air, is not used up in burning. Hence air contains oxygen which supports combustion and nitrogen which does not.