Question

State one relevant observation for each of the following: 

1. When crystals of copper nitrate are heated in a test tube. 

2. When the gaseous product obtained by dehydration of ethyl alcohol is passed through bromine water.

3. When hydrogen sulphide gas is passed through lead acetate solution.

4. When ammonia gas is burnt in an atmosphere of excess oxygen.

5. At the Anode when aqueous copper sulphate solution is electrolysed using copper electrodes.

Answer 1

1. Release reddish brown gas NO₂ (Nitrogen-di-oxide) which turns freshly prepared Ferrous Sulphate solution brown. The residue left is black copper oxide. 

2. Ethyl alcohol on dehydration forms ethene which when passed through bromine water makes it colourless. 

3. The yellow lead acetate paper turns greyish black with hydrogen sulphide gas due to formation of lead (II) Sulphide. 

4. Ammonia bums with a green flame. 

5. Nothing is left at anode as copper atoms form copper ions and migrate towards cathode.