Question

6. On heating blue coloured powder of copper (II) nitrate in a boiling tube, black copper oxide
brown gax X is formed.
(a) Identify the type of reaction and the gas X
(b) Write balanced chemical equation of the reaction.
(c) Write the pH range of aqueous solution of the gas X.​

Answer 1

The balanced chemical equation for the given chemical change is as below.

Cu(NO₃)₂     --------->       CuO        +        NO₂         +      1½ O₂

blue                                 black              brown

OR

2Cu(NO₃)₂     --------->       2CuO        +        2NO₂         +      3O₂

blue                                   black                  brown

(a) The type of reaction is thermal decomposition reaction. The gas X is Nitrogen Dioxide.

(b) Balanced chemical equation written above.

(c) pH range : 0-6.9 , ie, acidic.

This is because when NO₂ is dissolved in water, nitric acid is formed.

NO₂ + H₂O ----------> HNO₃