Question

an oleum sample is labelled as 104.5 how many no of moles of sulphur atom are present in 100g of this sample​

Answer 1

answer : 1.24 mol

explanation : An oleum sample is labelled as 104.5% . means, 100g of oleum (H2S2O7) require, 4.5g water to form 104.5g sulphuric acid ( H2SO4).

given, mass of sample = 100g

molar mass of sample = molar mass of oleum = 2 + 64 + 112 = 178g/mol

so, number of mole of oleum molecules = 100/178

so, here we see in one molecule of oleum contains two atoms of Sulphur.

so, number of mole of sulphur atoms = 2 × 100/178 = 200/178 ≈ 1.24 mol

hence, number of moles of sulphur atoms are present in 100g of this sample is 1.24 mol.(approximately)