1. Saponification
What is saponification?
Everyday, people used the soap to clensing activity, such as to take a bath, to washing clothes, to
washing the motorcyle and other. A soap is the sodium or potassium salt of a long‐chain fatty acid.
Most solid soaps are sodium salts of the type to be made in this experiment. Soap are produce by
saponification process. Saponification is reaction between fat and strong alkali (such as potassium
hydroxide, sodium hydroxide) and produce soap and glycerol (fatty acids).
Who is discovered saponification?
Soap discovered by Abu Bakar Muhammad bin Zakaria al-Razi, he is a chemist from Persian. He is the
first people that made modern soap. Recipes to making soap also written by famous doctor from
Andalusia-Spain, He is named Abu al-Qasim al-Zahrawi aka Abulcassis (936-1013M).
How to make soap by saponification?
Animal fats and vegetable oils are the main materials to saponification reaction. In laboratory we
can make soap by saponification reaction. The fisrt, put of cooking oil into a 250‐mL beaker. Add
ethanol and sodium hydroxide solution. Ethanol used as solvent and as catalyst to speed up the
reaction. Stir the mixture in the beaker. Place the beaker on a wire gauze supported on a ring stand
and heat gently. Continue to stir as the heating is continued. Cup your hand and waft the vapors to
your nose. The heating is continued until the odor of alcohol has disappeared and a pasty mass
remains in the beaker. This pasty mass is a mixture of the soap and the glycerol freed in the
mixture. Turn off the burner and allow the beaker to cool to room temperature on the ring stand.
What is the properties of soap?
Heat capacity of soap is 0.56 Cal / g. The density of pure soap in the range of 0.96 g / ml - 0.99 g / ml.
Soap have higher viscosity than the oil or fat before saponification reaction. Soap viscosity depends
on the temperature and composition of soap fats or oils are mixed. Above 75o
C the viscosity of soap
can not increases, but under 75o
C the viscosity of soap will increases. Soap is alkaline. Soap is
alkaline salts of fatty acids high rate so that it will partially hydrolysed by water, because it is a
solution of soap in water is alkaline. Soap produce froth or foam soap, if a solution of soap in water
stirred, it will produce a froth. Soap is the sodium salts of the long‐chain fatty acids are typical
surface‐active agents. They have a polar end which is hydrophilic (water loving) and a long nonpolar
chain which is hydropobic (watr hating). A a consequence they can form emulsions by suspending
oil in water when their nonpolar end is in the oil and their polar end is in the water.
How the soap can cleaning the clothes?
When the soap added to water, the soap molecules lower the surface tension of the water, so that it
wets objects more easly. The molecules also interact with the grease present. The hydrophobic
hydrocarbon chain is attracted to the grease and becomes embedded in it. The hydrophilic ionic
head of molecules sits outside the grease, in contact with water. When the water is agaited, the
grease is released from the cloth fibre or dish and is completly surrounded by soap molecule. Rinsing
with fresh water removes these grease.
How many types of soap?
There are two type of soap. The first is soap detergents generally called soaps, it are made from
animal fat or vegetable oils. The second is soapless detergents, usually just called detergents, it are
made using chemical oil.