A 0.324 g sample of an organic compound having a molar mass of 162 g mol ⁻¹ is subjected to Carius estimation for sulphur. The process yields 1.398 g of barium sulphate precipitate. The number of sulphur atoms present in one molecule of the organic compound is _______. (Given: Atomic mass of Ba = 137 u , S = 32 u , O = 16 u )

Step-by-step solution

Molar mass of BaSO ₄ = 137 + 32 + 4 16 = 233 g mol ⁻¹ Moles of the organic compound taken: n_ compound = 0.324 162 = 0.002 mol Moles of BaSO ₄ formed: n_ BaSO ₄ = 1.398 233 = 0.006 mol Since one mole of BaSO ₄ contains one mole of sulphur atoms, the moles of sulphur in the sample is 0.006 mol . The number of sulphur atoms per molecule of the compound is the ratio of moles of sulphur to moles of the compound: Number of S atoms = 0.006 0.002 = 3 Answer: 3