ACTIVITY NO.
7
LIPIDS
Lipids are poorly soluble in water but they dissolve in organic solvents like benzene or
chloroform. Their functions are to act as metabolic fuel, as stored forms of energy, and as components
of the cellular membrane. Lipids are classified into fatty acids, triglycerides, sphingolipids and steroids.
The alkali metal salts of fatty acids usually containing 10 to 18 carbon atoms are called soaps.
They have long nonpolar, oil-soluble hydrocarbon chain at one end and the water-soluble carboxylate
ion at the other end. This makes soap a good wetting agent and also emulsifying agent. The ability of
soap to suspend substances that do not dissolve in water makes it good cleaning agents. However, soaps
form insoluble salts with metal ions like Ca and Mg ions. These ions are present in hard water, forming
precipitates that adhere to sinks and even to clothes. The development of synthetic detergents solved
the problem of “scum” formation with soap.
The degree of unsaturation of lipids can be determined by adding iodine in CCl4. The free I2
attaches itself to the carbons with double bonds. The presence of unsaturation is indicated by the
decolorization of the added iodine.
OBJECTIVES
1. To examine some physical and chemical properties of lipids
2. To prepare soap
MATERIALS
Olive oil Cholesterol granules
Oleic acid Iodine in CCl4
Peanut oil Determent
Corn oil Soap
Linseed oil NaOH
Coconut oil Concentrated H2SO4
Cotton seed oil Acetic anhydride
PROCEDURES
Test for Unsaturation
Place 5 drops of olive oil, oleic acid, peanut oil, corn oil, linseed oil in six separate test tubes.
Add bromine in CCl4, shaking it until a reddish-brown color persists. Take care to prevent
cross contamination of samples. Record the number of bromine drops consumed.
Substance Tested No. of drops of Bromine used
Olive oil 9
Oleic acid 11
Peanut oil 8
Corn oil 10
Linseed oil 9
Coconut oil 12
QUESTIONS
1. What is emulsification?
The process of dispersing one immiscible liquid in another immiscible liquid is called emulsification.
Some common emulsifying agents are detergents and soaps, etc. An emulsion happens when small
droplets of the dispersed solution, which is often oil based are dispersed throughout the continuous
solution, which is often water based.
2. How are lipids related to production of soaps and detergent?
Lipids are related to the production of soaps and detergents because detergents are derivatives of
cholesterol, a type of lipid. Also, soap and detergent is the product of a Saponification or basic
hydrolysis reaction of a fat or oil.
3. How is soap made? Discuss the procedure.
The production of soap is called Saponification. It is the chemical reaction in which the building blocks
of fats and oils that react with lye to form soap. Saponification literally means "turning into soap"
from the root word, sapo, which is Latin for soap. Through saponification reaction, for the procedure
in making soap I will discuss the steps needed. First, measure 2ml of castor oil and transfer the oil into
a 100 ml beaker, after that measure 5 ml of ethanol and mix it into the castor oil, so that the oil will
dissolve better. Next step, carefully measure 10 ml of 5.0 M sodium hydroxide and add it to the
beaker containing the castor oil and ethanol. In a separate larger beaker add 100 ml of hot water, and
place 100 ml beaker containing the oil and alkali gently inside the larger beaker and stir it for 5
minutes. After that, measure 10 ml of saturated (NaCl) sodium chloride, next is to add it to the mix of
oil and alkali containing the soap and glycerol and stir it. After that cool the mixture by transferring
the beaker from hot water to iced water. Leave the mixture for 15 minutes, by stirring it occasionally
means, every minute. After 15 minutes, it’s time to filter off the precipitate, and wait it until the
filtrate has finish. That’s how soaps are made using saponification reaction.
4. Which is a better emulsifying agent, soap or detergent? Justify your answer.
Soap is better emulsifying agent, soap is an excellent cleanser because of its ability to act as
an emulsifying agent. Soap is much better for the environment rather than detergents.Soap is a
substances that, when dissolved in water, possess the ability to remove dirt from surfaces such as
the human skin, textiles, and other solids.Most common cleaning product in our everyday life.
GENERALIZATION
In this activity I learned that within the body, lipids have multiple functions. Also, I learned about soap and
detergent that soap is a salt of a long chain fatty acid which is produced from the hydrolysis of fats and oil
under alkaline condition. Detergents are usually made from synthetic resources such as petroleum
fractions. Saponification of fats and oils is the most widely used soap-making process. Both soap and
detergent are emulsifying agent, they play an essential role in our daily lives because they are both a
cleaning products. Soap and detergents are safe and effective for removing dirt such as human skin.
