Question

The solubility of benzoic acid in water is 0.05 g/100 ml at 0oC and 7.87 g/100 ml at 100oC. Answer the following questions if 5.69 grams of benzoic acid were to be heated to boiling in 100 ml of water. What would be the maximum possible percent recovery in a second batch, if the mother liquor was reduced to 44.09 ml, chilled in ice water and vacuumed filtered? Put your answer in 3 significant figures.

Answer 1

m = 5.69 g in 100 mL, at 100|C --> soluble

m = 0.05 g of benzene remains in V = 100 mL --> 0°C

mass crystalized = 5.69 -0.05 = 5.64 g

this is per 100 mL, but was reduced to

V = 44.09 mL

then

mass --> 44.09/100*5.64 = 2.486676 g recovered

2.49 g of benzene will be recovered