Answer to Question #160348 in Organic Chemistry for Stephanie Clark

Question

In Water:

                                   0 degrees Celsius       25 degrees Celsius     100 degrees Celsius

                                   0.0017 g/ml               0.00344 g/ml             0.05613 g/ml

           In Cyclohexane

                                   0 degrees Celsius       25 degrees Celsius     100 degrees Celsius   

                                   0.0062 g/ml               0.0086 g/ml               0.0869 g/ml

1)   A chemist need to separate benzoic acid from 4-hydroxybenzoic acid. The mixture is thought to contain 5.00 grams of benzoic acid and 1.00 grams of 4-hydroxybenzoic acid. Water is the intended recrystallization solvent.

a.    What is the minimal amount of water needed for the recrystallization? Show all calculations and explain your thinking. The objective is to get pure benzoic acid.

b.    What is the maximum recovery of benzoic acid in grams?

Answer 1

1- 78.45Kj

a)- 65.6 gram water

b)- -8403.50kj/mol