(i) Explain about the procedure and calculation behind the carius method of estimation of sulphur. (ii) What is the differencebetween distillation, distillation under reduced pressure and stream distillation?

(i) Explain about the procedure and calculation behind the carius meth

1.	(i) Explain about the procedure and calculation behind the carius method of estimation of sulphur. (ii) What is the differencebetween distillation, distillation under reduced pressure and stream distillation?
Answer» Solution :(a) (i) Carius METHOD 1. Procedure: A known mass of the organic COMPOUND is taken in a clean carius tube and few mL of fuming `HNO_(3)` 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_(2)` is added to the beaker `H_(2)SO_(4)` formed is converted to `BaSO_(4)` (white ppt.) The precipitate is filtered, washed, dired and weight. From the mass of `BaSO_(4)`, percentage of S is calculated. 2. Calculation: Mass of organic compound =Wg Mass of `BaSO_(4)` formed =xg 233g of `BaSO_(4)` contains 32g of SULPHUR `:. x g` of `BaSO_(4)" contain " (32)/(233) xx x g` of sulphur Percentage of sulphur `= ((32)/(233) xx (x)/(w) xx 100)%` (ii) Distillation is used in case of volatile liquid mixed with a non-volatile impurities. Distillation under reduced pressure: The method is used to purify such liquids which have very high boiling points and which decompose at or below their boiling points. Steam distillation is used to purify steam volatile liquids associated with water immiscible impurities.