Question

In the Carius method, the sealed Carius tube containing organic compound, fuming nitric acid and silver nitrate is heated at ${300^ \circ }C$ for six hours in the estimation of halogens.
A.True
B.False

Answer 1

Hint: We know that quantitative analysis is an analysis method that is used to obtain the number of elements or molecules produced during a chemical reaction. We can say the Carius halogen method in analytical chemistry is used for the quantitative determination of halogen in chemical substances.

Complete step by step answer:
We can estimate halogens by Carius method.
The principle of the Carius method is that when we heat an organic compound composed of halogen in a sealed tube with fuming nitric acid, in the presence of additional silver nitrate, we get the formation of silver halide.
In the Carius method, a known mass of the compound is heated with concentrated nitric acid in the presence of silver nitrate in a hard glass tube. The hard glass tube is known as Carius tube. Carbon dioxide and water are formed by the oxidation of carbon and hydrogen respectively. Corresponding AgX is formed by the halogen. We have to filter, dry and weigh it.
We can calculate the percentage of X using the formula,
Percentage of X$ = \dfrac{{\left( {{\text{Atomic mass of X}}} \right)}}{{{\text{Molecular mass of AgX}}}} \times \dfrac{{\left( {{\text{Mass of AgX}}} \right)}}{{{\text{Mass of compound}}}} \times 100$

The given statement In the Carius method, the sealed Carius tube consisting of organic compound, fuming nitric acid and silver nitrate is heated at ${300^ \circ }C$ for six hours in the determination of halogens is true.


Note:
The need for adding the nitric acid is to oxidize carbon and hydrogen. Concentrated nitric acid oxidizes iodine to iodic acid and doesn't show any other halogens. Even the oxidation of iodine by concentrated nitric acid occurs at higher temperatures only.
Estimation of sulfur by Carius method:
We have to take a known mass of the compound and heat it with concentrated nitric acid in the presence of a solution of barium chloride in the Carius tube. Sulfuric acid is formed by the oxidation of sulfur and Barium sulfate is obtained as precipitate when we add extra barium chloride. We then dry and weigh barium sulfate.
We can calculate the percentage of sulfur using the formula,
Percentage of sulfur$ = \dfrac{{\left( {{\text{Atomic mass of S}}} \right)}}{{{\text{Molecular mass of BaS}}{{\text{O}}_4}}} \times \dfrac{{\left( {{\text{Mass of BaS}}{{\text{O}}_4}} \right)}}{{{\text{Mass of compound}}}} \times 100$
The quantity of sulfur obtained by Carius method is estimated by Barium sulfate $\left( {BaS{O_4}} \right)$.