Question 17
Solubility and SolutionsThe solubility of copper (II) tetraoxosulphate (VI) is 75 g in 100 g of water at 100°C and 25 g in 100 g of water at 30°C. What mass of the salt would crystallize, if 50 g of copper (II) tetraoxosulphate (VI) solution saturated at 100°C were cooled to 30°C?
- A.57.5 g
- B.42.9 g
- C.28.6 g
- D.14.3 g
Show the answer and explanation
Answer: D (14.3 g)
Explanation
175 g of saturated solution at 100°C holds 75 g of salt, and 50 g of solution is 2/7 of that. Cooling 175 g of solution drops 50 g of salt, so 50 g drops 50 × 50/175 = 14.3 g.