Dry Heating Test

The salt is heated gently and then strongly in a clean and dry test tube.

Observations

Solid melts and resolidifies: Salts of calcium may be present

Solid swells up: phosphate may be present

Solid decripitates (Cracking sound): Lead nitrate may be present

Solid sublime and vapour are white in colour: Ammonium chloride may be present

Precautions

1. Use a perfectly dry test tube for performing this test.
2. Keep the mouth of the test tube away from yourself as well as from your neighbouring students.
3. During heating, do not heat the tube at one point but keep it rotating otherwise the tube may crack.
4. Do not smell the gases evolved by placing the nose directly over the mouth of the tube. Always smell the gas by puff of your hands.