Question

8. Give two examples of each of the following
changes occurring during a chemical
reaction:
(a) Change of state of the reactants
(b) Change of colour
(c) Evolution of a gas
(d) Formation of a precipitate
​

Answer 1

formation of precipitate

Answer 2

Answer:

1. Change in colour :

The reaction between lead nitrate solution and poassium iodide solution.

Chemical equation as follow :

Pb ( NO₃ )₂ + 2 KI  ⇒  PbI₂ + 2 KNO₃

In above reaction colour change from colourless to yellow.

2. Change in temperature :

The reaction between dil. sulphuric acid on zinc.

Chemically :

Zn + H₂SO₄  ⇒  ZnSO₄ + H₂

Heat evolved in the above reaction.

3. Formation of precipitation​ :

The reaction between barium chloride on sodium sulphate.

Chemically :

BaCl₂ + Na₂SO₄  ⇒  BaSO₄ + 2 NaCl

In the above reaction white ppt. of BaSO₄ will form.