CuSO₄·5H₂O containing 3.5 percent of a soluble impurity is dissolved continuously in sufficient water and recycled mother liquor to make a saturated solution at 80°C. The section is then cooled to 25°C, and crystals of CuSO₄·5H₂O are thereby obtained These crystals carry 10 percent of their dry weight as adhering mother liquor. The crystals are then dried to zero free water (CuSO₄·5H₂O). The allowable impurity in product is 0.6 percent. Calculate

(a) The weight of water and of recycled mother liquor required per 100 kg of impure copper sulfate; 

(b) The percentage recovery of copper sulfate, assuming that the mother liquor not recycled is discarded. The solubility of CuSO₄·5H₂O at 80°C is 120 g per 100 g of free H.O and at 25C is 40 g per 100 g of free H₂O.