Question

An experiment is conducted in the laboratory by heating the mixture of sodium acetate and soda lime. With respect to the above experiment answer the following.
A.Name the gas evolved and wrote its molecular formula.
B.Write the balanced chemical equation for the above reaction.
C.How the gas evolved is collected?
D.The gas liberated does not react with nitric acid. Give reason.

Answer 1

Soda Lime is sodium hydroxide $\left( {{\text{NaOH}}} \right)$. When a mixture of sodium acetate $\left( {{\text{C}}{{\text{H}}_3}{\text{COONa}}} \right)$ and soda lime is heated, sodium carbonate is produced with an evolution of an unsaturated hydrocarbon gas.

Complete step by step answer:
A.The reaction of sodium acetate and soda lime used for preparation of methane gas.
Thus, the gas produced when a mixture of sodium acetate and soda lime is heated is methane.
The molecular formula for methane is ${\mathbf{C}}{{\mathbf{H}}_{\mathbf{4}}}$.
B.The reaction of sodium acetate and soda lime used for preparation of methane gas. In the reaction, sodium carbonate is produced as a by-product.
Thus, the chemical reaction is,
${\text{C}}{{\text{H}}_{\text{3}}}{\text{COONa}} + {\text{NaOH}} \to {\text{C}}{{\text{H}}_{\text{4}}} + {\text{N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}$
Count the number of all the atoms. Thus,
${\text{C}}{{\text{H}}_{\text{3}}}{\text{COONa}} + {\text{NaOH}} \to {\text{C}}{{\text{H}}_{\text{4}}} + {\text{N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}$
${\text{ C}} - 2{\text{ C}} - 2$
${\text{ H}} - 4{\text{ H}} - 4$
${\text{ O}} - 3{\text{ O}} - 3$
${\text{ Na}} - 2{\text{ Na}} - 2$
The number of all the atoms on the reactant and product side are the same. Thus, the balanced chemical equation is,
${\mathbf{C}}{{\mathbf{H}}_{\mathbf{3}}}{\mathbf{COONa + NaOH}} \to {\mathbf{C}}{{\mathbf{H}}_{\mathbf{4}}}{\mathbf{ + N}}{{\mathbf{a}}_{\mathbf{2}}}{\mathbf{C}}{{\mathbf{O}}_{\mathbf{3}}}$

C.In the reaction, methane gas is evolved. Methane does not react with water. The gas evolved is collected by the downward displacement of water.
Downward displacement of water means the gas rises upwards in the collector jar displacing the water downwards.
4.The gas liberated in the reaction is methane. Methane is a saturated hydrocarbon. Nitric acid is a strong oxidizing agent.
Thus, being a saturated hydrocarbon methane does not react with nitric acid.

Note:
Methane gas produced in the reaction is lighter than water. Thus, when methane gas is collected, it is collected by the downward displacement of water.
Downward displacement of water means the gas rises upwards in the collector jar displacing the water downwards.
Also, methane gas does not react with water. Thus, this method of collecting methane gas is preferred.