Question

Name the gas evolved when the following mixtures are heated:
A.Calcium hydroxide and Ammonium chloride
B.Sodium nitrite and Ammonium chloride

Answer 1

Hint: When calcium hydroxide reacts with ammonium chloride the gas evolved has pungent smell and is made up of nitrogen and hydrogen. When sodium nitrite reacts with ammonium chloride an inert diatomic gas is evolved which is present in high amounts in our atmosphere.

Complete step by step answer:
-The molecular formula for calcium hydroxide is \[{\text{Ca}}{({\text{OH}})_2}\]
-The molecular formula for ammonium chloride is \[{\text{N}}{{\text{H}}_4}{\text{Cl}}\]
-The molecular formula for sodium nitrite is \[{\text{NaN}}{{\text{O}}_2}\]
-Let us write the decomposition reaction for the given mixture of reactant when calcium hydroxide reacts with ammonium chloride. The products formed are calcium chloride, ammonia gas and water. The reaction is as follow:
\[{\text{Ca}}{({\text{OH}})_2} + 2{\text{N}}{{\text{H}}_4}{\text{Cl}} \to {\text{CaC}}{{\text{l}}_2} + 2{\text{N}}{{\text{H}}_3} + {{\text{H}}_2}{\text{O}}\]
Hence the gas evolved in the first case is ammonia.
When sodium nitrite reacts with ammonium chloride we get sodium chloride, dinitrogen and water. The reaction occurs as follow:
\[{\text{NaN}}{{\text{O}}_2} + {\text{N}}{{\text{H}}_4}{\text{Cl}} \to {\text{NaCl}} + {{\text{N}}_2} + 2{{\text{H}}_2}{\text{O}}\]
The gas evolved here is nitrogen gas.

Additional information:
The atomic number of nitrogen is 7 and it belongs to group number 15 of the modern periodic table. Nitrogen exists as a gas in its most stable state. It is among the most abundant elements. Nitrogen almost occurs everywhere, we saw nitrogen in the amino acids, protein and as a nucleic acid in DNA and RNA. It also occurs in the energy unit ADP that is adenosine triphosphate. Nitrogen gas contains a triple bond and this triple is the second strongest bond in a diatomic molecule. The strongest triple bond in a diatomic molecule is in carbon monoxide.

Note:
Ammonia is a binary compound made up of two elements that is nitrogen and hydrogen in the ratio 1 is to 3. Ammonia is widely used as fertilizers. It is used as a cleaner for many surfaces.