jotter note ex 4

PROCEDURE

Part A

Preparation of Soap

A NaOH solution was prepared.

(0.25 g sodium hydroxide dissolved in a mixture of 1.0 ml of distilled water and 1.0 ml of 95% ethanol.)

0.25 g of fat was placed in a 50 ml conical flask and the prepared sodium hydroxide solution was added into the flask.

The mixture was heated in a bath of 100 oC.

The flask was covered with some aluminium foil. The Erlenmeyer flask was swirled for few minutes by using tong.

The soap will precipitate from the boiling mixture within 20 minutes.

0.4 ml of a 50 % water/alcohol mixture was added to replace the solvent if observed that some alcohol and water had evaporated.

The mixture was heated for a maximum time of 25 minutes.

4 ml of NaCl solution was placed in a 15 ml beaker and the saponified mixture was transferred from flask to beaker.

The mixture was stirred while the beaker was cooled in an ice-water bath.

The prepared soap was collected on a Hirsch funnel of ice cold distilled water to remove excess NaOH.

Air was continuously drawn through the filter for a few minutes to partially dry the product.

Part B

Testing on prepared Soap

0.01 g of soap was removed from the filter paper and was placed in a clean 10 ml graduated cylinder.

3 ml of distilled water was added, the cylinder was closed with a thumb and the mixture was shaken vigorously for 15 seconds.

The level of the foam was noted down after 30 seconds standing.

The pH of the aqueous solution was checked.

5-10 drops of 4% calcium chloride solution was added to the soap mixture from a Pasteur pipette. The mixture was shaken for 15 sec and was allowed to stand for 30 seconds. The

effects of the addition of calcium chloride were observed.

0.5 g of trisodium phosphate was added and the mixture was shaken again for 15 seconds. The results were observed again after 30 seconds.

Conditions Observation

1. Soap + 3 ml distilled water

2. Test with litmus paper

3.Mixture from No 1 + 5~10

drops of 4% calcium chloride

4.Mixture from No 2 + 0.5 g

trisodium phosphate

RESULTS