Question

Give the principle and formula involved in the estimation of halogen by carius method

Answer 1

A known mass of an organic compound is heated with fuming nitric acid in the presence of silver nitrate contained in a hard glass tube, known as Carius tube, in a furnace.
Carbon and hydrogen present in the compound are oxidised to carbon dioxide and water. The halogen present forms the corresponding silver halide (AgX). It is filtered, washed, dried and weighed.

Let the mass of organic compound taken = m g

Mass of AgX formed = m1 g

1 mol of AgX contains 1 mol of X

Mass of halogen in m1 g of AgX = (atomic mass of X x m1)/(molecular mass of AgX)

Answer 2

Principle in the estimation of halogen by carius method:

When the known mass of organic compound is heated with nitric acid (fuming) in the presence of silver nitrate.

Due to the temperature raise, the hydrogen and carbon atoms in organic compound forms carbon dioxide and water.

The halogen from the organic compound reacts with silver nitrate to from AgX where Ag is silver and X is halogen.

When the obtained AgX is washed, dried and weighed. We get the quantity of X.

Carius method is used to find the quantity of halogen present in the compound.

Formula in the estimation of halogen by carius method:

Mass of organic compound = m g

Mass of AgX formed = m1 g

I g of AgX contains 1 g of X

$\mathrm{Mass \ of \ halogen \ in} \ m_{1} g of \mathrm{Ag} \mathrm{X}=\frac{\text { Atomic mass of } \mathrm{X} \times m_{1} \mathrm{g}}{\text { Molecular mass of } \mathrm{AgX}}$

$\text { Percentage of halogen will be }=\frac{\text { Atomic mass of } \mathrm{X} \times m_{1} }{\text { Molecular mass of } \mathrm{AgX} \times m}\times 100$