Physical Properties

Preparation of Oxygen Oxygen is prepared in lab generally in two ways either by the application of heat or no application of heat. Using heat: Oxygen in lab is prepared by heating the mixture of powdered potassium chlorate and manganese dioxide in the ratio 4:1 in a hard glass test tube. The oxygen gas is observed in a gas jar through the downward displacement of water. The reaction involved is given below: 2KClO3−→−−−−−MnO2200−300∘C2KCl+3O2↑ Without heat:  The dry sodium peroxide is taken in a conical flask and the apparatus is fitted as shown in figure. The two necks of woulfe’s bottle ... Read more

  Preparation of nitrogen Nitrogen is found in both free and combined states. It occupies 78.07% by volume. Nitrogen can be prepared: By heating copper in air: Firstly, air is passed through lime water and then concentrated sulphuric acid to make the air free from carbon dioxide and moistures respectively. The air contains only nitrogen and oxygen which are passed over the heated copper wire as shown in the figure. Here copper combines with oxygen to make copper oxide and nitrogen gas passes over. This nitrogen can be collected by downward displacement of water. By burning phosphorous in air: Nitrogen ... Read more