CuSO4 H20 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 solution is then cooled to 25°C and crystals of CuSO4 5H,O thereby obtained. These crystals carry 10 percent of their dry weight as adheringmother liquor. The crystals are then dried to zero free water (CuS04 ' 5H20). The allowable impurity in the 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. T;,e solubility of CuS04 ' 5H2 0 at 80'C is 120 g per 100 g of free H20 and at 25'C is 40 g per 100 g of free H20.