Question

On heating blue coloured powder of copper (II) nitrate in a boiling tube, copper oxide (black), oxygen gas and a brown gas X is formed

(a) Write a balanced chemical equation of the reaction.

(b) Identity the brown gas X evolved.

(c) Identity the type of reaction.

(d) What could be the pH range of aqueous solution of the gas X?

Answer 1

(a) Balanced chemical equation 

\(2Cu(NO_3)_2(s)\overset{Heat}\rightarrow 2CuO(s) +O_2(g)+4NO_2(g)\)

(b) The brown gas X evolved is nitrogen dioxide (NO₂ ) 

(c) This is a decomposition reaction 

(d) Nitrogen dioxide dissolves in water to form acidic solution because it is an oxide of non-metal. Therefore, pH of this solution is less than 7.