Carius method:
(I) Procedure:
A known mass of the organic compound is taken in a clean carius tube and few mL of fuming HNO3 is added and then the tube is sealed. It is then placed in an iron tube and heated for 5 hours. The tube is allowed to cool and a hole is made to allow gases to escape. The carius tube is broken and the content collected in a beaker. Excess of BaCl, is added to the beaker. BaSO4 formed is converted to BaSO4 (white ppt.) The precipitate is filtered. washed, dried and weight. From the mass of BaSO4 , percentage of S is calculated.
(ii) Calculation:
Mass of organic compound = Wg
Mass of BaSO4 formed = r g
233 g of BaSO4 contains 32 g of sulphur
\(\therefore\) x g of BaSO4 contain \(\frac{32}{233}\times\mathrm x\) g of sulphur
Percentage of sulphur = \(\Big(\frac{32}{233}\times\frac{x}{w}\times100\%\Big)\)
