Report

Evaluation
TOTAL

Chem 209 Lab Report

Experiment 2: Crystallization

Student Name______Date______

Student ID #______Section______

A-Selection of a crystallizing solvent

I-Purpose:

II-Table of Reagents:

Compound /

Formula

/ M.Wt.
(g/mol) / Melting point (ºC) / Boiling point (ºC)

III-Results:

Compound / Water / Toluene / Ligroin / Best solvent for Recrystallization
Cold / Hot / Cold / Hot / Cold / Hot

IV-Discussion of Results:

B- Recrystallization of Acetanilide

I-Purpose:

II-Table of Reagents:

Compound /

Formula

/ M.Wt.
(g/mol) / Melting point (ºC) / Boiling point (ºC)

III-Results:

Structure of acetanilide / Mass used (g) / Mass recovered (g) / % Recovery
Acetanilide / Melting point
Crude
Pure

IV-Discussion of Results:

C- Decolorization of Brown Sugar

I-Purpose:

II-Table of Reagents:

Compound /

Formula

/ M.Wt.
(g/mol) / Melting point (ºC) / Boiling point (ºC)

III- Observation:

IV-Discussion of Results:

E-Answer to Questions:

1. Would you recommend suction filtration for a solution in which ether is the solvent? Explain.

2.  Why is it important to minimize evaporation during the filtration of the hot solution?

3.  An organic chemist has an impure solid (X) which is soluble in water to the extent of 3 g per 100 ml of water at room temperature and 15 g per 100 ml of water at 100 °C. 10 g of X has 1 g of impurity A (A has the same solubility in water as X) and 0.40 g of impurity B (B is insoluble in water). How could you purify X? How many grams of pure X could be obtained after one recrystallization from water?

4.  The solubility of an organic material A in 100 ml of acetic acid is shown in the following table:

Temperature
(°C) / Mass
(g)
20 / 0.15
30 / 0.20
60 / 0.25
80 / 0.40
100 / 0.50
110 / 0.65
118 / 3.00

Two students recrystallized 10 g samples of A from acetic acid, the first dissolving A at 100 °C and filtering at 20 °C, the second dissolving the acid at 110 °C and filtering at 30ºC. Calculate the quantity of acetic acid each student was required to use and the percentage recovery of A possible in each case.