In the estimation of element X in an organic compound, 0.8 ~g of the compound containing X was heated with fuming HNO ₃ and the cooled product was treated with barium chloride. The mass of barium sulphate precipitated was 1.2 ~g . What is the percentage of element X and what is the formula of the violet-coloured compound formed when Lassaigne's extract of the organic compound is treated with sodium nitroprusside?

Step-by-step solution

The element X is sulphur because the treatment with fuming HNO ₃ followed by BaCl ₂ results in the precipitation of BaSO ₄ . The molar mass of BaSO ₄ is 137 + 32 + 4 16 = 233 g/mol . The mass of sulphur in 1.2 g of BaSO ₄ is calculated as: Mass of S = 32 233 1.2 0.1648 g . The percentage of sulphur in the organic compound is: % S = Mass of S Mass of compound 100 = 0.1648 0.8 100 = 20.6 % . When Lassaigne's extract containing Na ₂ S is treated with sodium nitroprusside, Na ₂[ Fe ( CN )₅ NO ] , a violet-coloured comp