Question

State the characteristics of chemical reaction with respect to change in colour and

formation of precipitate.​

Answer 1

Answer:

A chemical reaction is a chemical change where substances react with each other to form a new substance.

(i) addition of dilute acid to an active metal - The test tube becomes hot and hydrogen gas is evolved, which means heat is produced.

(ii) Addition of dilute hydrochloric acid to silver nitrate - A white coloured precipitate is formed which is AgCl

(iii) Addition of water to quicklime - The solution boils and heat is produced accompanied by a hissing sound.

(iv) Thermal decomposition of mercury oxide - The colour of mercury changes from red to silvery, that is metallic

Answer 2

Answer:

Formation of precipitate. Some chemical reactions are characterised by the formation of precipitate. When a insoluble solid substance remains

Change in colour. Some chemical reactions are characterised by change in colour.