Question

Q1. Write the chemical equation of the reaction in which the following changes have taken place with an example of each:
(a) Change in colour (b) Change in temperature (c) Formation of precipitate.

Answer 1

(a)
a) Fe + CuSO4 ------------> FeSO4 + Cu
b) -------
c) NaCl + AgNO3 ------> AgCl (ppt) + NaNO3

Answer 2

Answer:

(i)Cu (s) + 2AgNO3 (aq)———–> Cu(NO3)2(aq) + 2Ag

The solution will become blue in colour and shiny silver metal will be deposited.

(ii) NaOH + HCl ———–> NaCl + H2O+ heat

The temperature will increase because heat will be evolved.

(iii) Pb(NO3)2 (aq) + 2KI (aq)———–> Pbl2 (s) + 2KNO3 (aq)

Yellow ppt

Yellow precipitate of Pbl2will be formed.