Question

Calcium burns in nitrogen to produce a white powder which dissolves in sufficient water to produce a gas (A) and an alkaline solution. The solution on exposure to air produces a thin solid layer of (B) on the surface. Identify the components A and B.

Answer 1

Calcium metal when burns with nitrogen to form calcium nitride along with trace of calcium oxide is also formed which further absorbs moisture in the water to form ammonia gas and alkaline solution, calcium hydroxide. Calcium hydroxide which on further exposure to air to form thin solid surface of calcium carbonate

${ Ca }_{ (metal) }\quad +\quad { N }_{ 2(g) }\quad \rightarrow \quad { Ca }_{ 3 }{ N }_{ 2 }\quad +\quad { H }_{ 2 }O\quad \rightarrow \quad Ca{ \left( OH \right) }_{ 2 }\quad +\quad { NH }_{ 3(g) }\quad +\quad air\quad \rightarrow \quad Ca{ CO }_{ 3 }$

A: Ammonia gas

B: Calcium hydroxide

C: Calcium carbonate