EXP 4: Separation & Purification of Organic Compounds

Recrystallization

Solid is dissolved in a solvent and put in crystalline form under conditions that ensure greater purity

Use solvent with high solubility for the compound when hot but only moderate solubility when cold

Simplest way to obtain pure precipitate

Impure acetanilide (90% C6H5NHCOCH3 + 10% NaCl) + Water + Congo Red

Recrystallization: What was initially heated?

Impurify the substance

Use of congo red

Animal charcoal

Recrystallization: What is added after the solution in the beaker is initially stirred then continued heating?

Clear

Recrystallization: What color should the filtrate be?

Crystals are larger in undisturbed flask

Recrystallization: What is the difference between the crystals in the disturbed (placed in a water bath) vs undisturbed (not placed in water bath) flask?

(Actual Yield)/(Theoretical Yield) * 100

Recrystallization: Percent Yield Formula

4.5g

Recrystallization: What was the theoretical yield?

Benzoic acid (C6H5COOH) contaminated with NaCl + 100 mL water

Extraction: What is initially placed in the beaker then heated?

chloroform (CHCl3)

Extraction: What is the second solvent that is added to the beaker after the benzoic acid has been dissolved in water?

Chloroform (CHCl3), Ethylether benzene, Carbon Tetrachloride (CCl4), Carbon Disulfide (CS2)

Extraction: What are the 4 suitable liquids for extraction from water?

Below

Extraction: Where does the chloroform layer lie in comparison to the water layer?

Benzoic acid (C6H5COOH)

Extraction: The CHCl3 layer is then extracted and heated. What is the residue the remains?

nitric acid (HNO3) & silver nitrate (AgNO3)

Extraction (Test for Chlorides): 5-10 mL of the water layer is obtained. What 2 compounds were added?

white; silver chloride (AgCl)

Extraction (Test for Chlorides): What is the color, name, and formula of the precipitate that forms?

NaCl + AgNO3 —> AgCl + NaNO3

Extraction (Test for Chlorides): What is the chemical equation of the reaction?

Sublimation

Occurrence when substance passes directly from solid to gaseous state when heated and from vapor to solid upon cooling

Benzoic acid (C6H5COOH) contaminated with NaCl

Sublimation: What is placed in a 400mL beaker?

White fibrous sublimate

Sublimation: What is formed after the C6H5COOH is heated?