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JAMB Chemistry 1979 Question 19

Question 19

Solubility and Solutions

12 g of solid potassium chlorate (KClO3) were added to 40 g of water and heated to dissolve all the solid. As the solution cools, crystals of potassium chlorate started forming at 66°C. The solubility of potassium chlorate at 66°C is therefore

  1. A.66
  2. B.33
  3. C.10
  4. D.20
  5. E.30
Show the answer and explanation

Answer: E (30)

Explanation

Crystals start forming when the solution is just saturated, so 12 g dissolve in 40 g water at 66°C. Per 100 g water: 12 × 100/40 = 30 g.