Question

The following techniques are used to estimate quantitatively other elements (nitrogen, sulphur & halogens) in organic compounds. Identify the name of the method and the element which is estimated by the following methods :

1. A known mass of an organic compound is heated with fuming nitric acid in presence of silver nitrate.
   
2. A known mass of an organic compound is heated with copper oxide in the atmosphere of carbon oxide.
   

Answer 1

(i) Carius method for quantitative analysis of halogens.

A mixture of organic compound & fuming $HN{O}_3$ is heated in presence of $AgN{O}_3$.

$C$ & $H$ present are oxidized to $C{O}_2$ & $H_{2}O$. Halogen present forms Silver halide, which is filtered, washed, dried & weighed.

(ii) Dumas method for quantitative analysis of nitrogen. A known mass of organic compound is heated with $CuO$ in atmosphere of $C{O}_2$.

The $C$ & $H$ are oxidized to $C{O}_2$ & water while $N$ is set free. It is collected over an aqueous solution of $KOH$. All gases except $N_2$ are absorbed. The volume of $N_2$ collected is measured.