The solubility of compound A in ethanol is .8g per 100ml at 0degreesC and 5.0g per 100ml at 78degreesC. What is the minimum amount of ethanol needed to recrystallize a 12.0g sample of compound A? How much would be lost in the recrystallization, that is, would remain in the cold solvent?

Answer 1

100 mL x 12g/5g = 240 mL = minimum amount ethanol to dissolve 12 g A.

0.8 g x 240/100 = 1.9 g is the solubility at 0o C in 240 mL so 1.9 g is what is lost. You would recover 12-1.9 = ??