REPORT 4 : LIPID

Title: Making a soap

Objective:

 To understand the making of soap.

Introduction:

       Soap is a form of lipid which is a mixture of sodium slats of various naturally occurring fatty acids. When air bubbles are added to a molten soap, the density of the soap decrease thus making it float on water. A softer soap lather results when the fatty acid salt contains potassium rather than sodium. Soap is the product of a saponification or basic hydrolysis reaction is as follows:

Fat + NaOH → Sodium salt of fatty acid + glycerol

This reaction occurs in two steps and the net effect is the broken ester bonds. The glycerol first turns back into an alcohol, then the fatty acid portion is turned into a salt due to the presence of the basic NaOH solution. The oxygen of carboxyl group now has a negative charge which attracts the positive sodium ion. 

Materials: 

60 ml of 6 M NaOH solution, 17.5 g of fat (Coconut oil, Corn oil, Palm oil, Margarine, Butter), 75 ml of distilled water, 300 ml hot sodium chloride (NaCl) solution, 100 ml graduated cylinder, 400 ml beaker, 250 ml beaker,Stirring rod, Colour and Fragrance

Procedure:

1. 40 ml of the 6 M NaOH and 17.5 g of fat was placed in to a 250 ml beaker.

2. The beaker was heated to boil over the lowest flame that will sustain the boiling process. The mixture was stir constantly to avoid spattering.

3. The mixture was continued boiling and stirring for about 20 minutes, or until most of the water has been evaporated.

4.  20 ml of NaOH solution was carefully added and continue boiling for an additional 20 minutes or until most of the water has boiled off.

5. As the crude soap cools, a waxy solid was formed. 12.5 ml of distilled water and 50 ml of hot and saturated NaCl solution was added.

6. The mixture was stirred, and the lump was break using stirring rod.

7. The solution was wash by pouring it through a wire screen, which will trap small soap perticles.

8. The wash process was repeated twice. After the final washing, the soap was pressed between two sheets of paper towelling to expel as much water as possible.

Result: 

Discussion:

On refluxing with alkali, triacylglycerol (fatty acid esters) are hydrolysed to give glycerol and potassium salts of fatty acids (soap), such process id known as saponification. The saponification value is the number of milligrams of KOH required to neutralize the fatty acids resulting from the complete hydrolysis of 1 g of fat. The saponification values gives an indication of the nature of the fatty acids constituent of fat and thus, depends on the average molecular weight of the fatty acids constituent of fat. The greater the molecular weight (the longer the carbon chain), the smaller the number of fatty acids is liberated per gram of fat hydrolysed and therefore, the smaller the saponification number and vice versa.

In this experiment, there are few sample that have been tested to determined its saponification value, which are butter, sunflower, corn oil, margarine and palm oil. All these samples have different saponification number after being tested. Based on this experiment, corn oil and palm oil have the lowest saponification number which is 28.06. This number indicates that both corn oil and palm oil have a long fatty acid chain length in triglycerides. While, the saponification number for sun flower, margarine, and butter is 33.67, 84.17, and 98.19 respectively. Butter have the highest saponification number in this experiment, this means fatty acid in butter lower than fatty acid in other samples.

Conclusion:

Based on this experiment, we have studied saponification of triglycerides. By heating a triglyceride in aqueous potassium hydroxide (KOH) the fatty acyl esters can be cleaved off (hydrolysis) leaving behind glycerol and the potassium salt of the fatty acid. The process is called saponification or soap formation, since the potassium salts of fatty acids are in fact. While, the saponification number used to indicates the fatty acid length in triglycerides.

Reflection:
1. TING MEE PING (D20141067055)
In this experiment, I have learned about saponification of triglyceride and how to determine its saponification number. Besides that, I also learned to always be careful especially when handling chemical substances which is corrosive.  

2. LENDRA NALAT ( D20141067021)

From this experiment, I have learned how to determine the saponification number.  I also learnt the chemical equation occur during the saponification which is:

Fat + NaOH → Sodium salt of fatty acid + glycerol. Beside that I can learn how to handle corrosive chemical.

3. CHRIS ROXA ANGELLA SUPAIN (D20141067094)
From this experiment that we had conduct, I had learn and understand on how to make a soap. I also once again improved my skill in titration. However in this experiment, our titration is using a corrosive chemical so I need to become extra careful during the titration. Besides that, I observed that butter have the highest saponification number. 

 

Before titration

  

After titration