Question

Question 39
On heating blue-colored powder of copper (II) nitrate in a boiling tube, copper oxide (black), oxygen gas, and a brown gas X are 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 the aqueous solution of the gas X?

Answer 1

(a) Balanced chemical equation:
2Cu(NO₃)₂(s)Heat→2CuO (s)+O₂(g)+4NO₂(g)
(b) The brown gas X evolved is nitrogen dioxide, (NO₂).
(c) This is a decomposition reaction as a single reactant is decomposing to form three products.
(d) Nitrogen dioxide dissolves in water to form an acidic solution. Therefore, the pH of this solution is less than 7. The reaction occurs as follows:
2NO₂(g)+H₂O (l)→HNO₂₍aq)+HNO₃(aq)