Chemistry - Stoichiometry Question with Solution | TestHub
One gram of a moist sample of a mixture of potassium chloride and potassium chlorate was dissolved in water and made up to 250 ml. Twenty-five millilitres of this solution was treated with SO₂ to reduce the chlorate to chloride and excess SO₂ was removed by boiling. The total chloride was precipitated as silver chloride. The weight of the precipitate was 0.1435 g. In another experiment, 25 ml of the original solution was heated with 30 ml of 0.2 N solution of ferrous sulphate and unreacted ferrous sulphate required 37.5 ml of 0.08 N solution of an oxidizing agent for complete oxidation. (K = 39, Ag = 108)
What is the mass per cent of moisture present in the moist sample?
Options:
Answer:
Solution:
Mass of KClO₃ = 5 mmol × 122.5 = 612.5 mg; mass of KCl = 5 mmol × 74.5 = 372.5 mg; total salts = 985 mg in the 1 g sample. Moisture = 1000 - 985 = 15 mg, i.e. 1.5%, matching (b).
