- **Estimation of sulphur**
- A known mass of an organic compound is heated in a Carius tube with sodium peroxideor fuming nitric acid Sulphur present in thecompound is oxidised to sulphuric acid
- It is precipitated as barium sulphate by addingexcess of barium chloride solution in water
- The precipitate is filtered, washed, dried andweighed
- $BaSO_4$
- 137 + 32 + $C_4= 233g BaSO_4$ (precipitated)
- 233g of $BaSO_4$ = 32g of S
- $x$ $gr$ of $BaSO_4$ =$\frac{32 \times x}{233}$
- % of S= $\frac{32 \times x \times 100}{233 \times m}$ = % of S
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