Explain the estimation of phosphorus and sulphur present in the organic compound

Explanation

Estimation of sulphur: A known mass of the organic compound is heated with sodium peroxide in a Carius tube. Then S is oxidised to `H_(2)SO_(4)`. The acid is precipitated as `BaSO_(4)` by adding excess of `BaCl_(2)` aq. Solution. The ppt. is filtered, wahed, dried and weighed.
Calculations:
Mass of organic compound =ag
Mass of barium sulphate =bg
Molecular weight of `BaSO_(4)=233`
1 mole of `BaSO_(4) or 233 g of BaSO_(4)` contains 32g of sulphur
`therefore b g" of "BaSO_(4)` contains ........? `=(32 xx b)/(233)` g of sulphur
a g of organic compound contains `(32 xx b)/(233)" g of sulphur"`
100 g organic compounds ..........?
`=(100 xx 32 xx b)/(a xx 233)" g of sulphur (% of S)"`
Estimation of phosphorus : A known mass of organic compound is heated with funning nitric acid in a Carius tube. Then phosphorus is oxidised to phosphoric acid. The acid is precipitated as ammonium phosphomolybdate by adding ammonia and ammonium molybdate solutions.
Calculation:
Mass of organic compound=a.g.
Mass of ammonium phosphomolydate =bg
Molecular weight of ammonium phosphomolybdate =1877
1877g of ammonium phosphomolybdate conatains 31 g of phosphorus
b'g of ..............?
`=(31 xx b)/(1877)` g of phosphorus.
'a g of organic compound contains `(31 xx b)/(1877)` g of phosphorus
`=(100 xx 31 xx b)/(a xx 1877)" g of P(% of P)"`