The soap making can be dated back to 2800 B.C Soaps are sodium or potassium salts of fatty acids acts as an emulsifie cleans skin, used in laundry for cleaning textiles

1. Article written and published
By
www.worldofchemicals.com
Chemistry of soaps - How soaps
really work?

2. What are soaps?
 Soaps are sodium or potassium salts of fatty
acids. They are produced from the hydrolysis of
natural oils or fats in a chemical reaction called
saponification. Soap is an excellent cleanser
which often occurs in form of solid bars or in liquid
form.
 Chemicals in soaps
 fatty acids, soaps, saponification, tallow, palm
kernel oil, sodium chloride, pentasodium
pentetate, emulsifier, hydrocarbon chains, lye

3. History of soaps
 The soap making can be dated back to 2800
B.C., with the evidence of Babylonians mastering
in the art of soap making. They made soap from
fats boiled with ashes. Soap was used in cleaning
wool and cotton used in textile manufacture and
was used medicinally for at least 5000 years.
Ancient Egyptians mixed animal and vegetable
oils with alkaline salts to produce a soap-like
substance. The Phoenicians used goat’s tallow
and wood ashes to create soap in 600BC. Early
Romans made soaps in the first century A.D.

4. Chemical composition of soaps
 Soap is salt of fatty acid. Various ingredients present in soaps
are –
 Water keeps the soap from becoming too brittle
 Coconut oil or palm kernel oil - sodium salts of fats tallow
 Hydrogenated tallow acid, coconut acid, glycerin – act as skin
conditioner
 Sodium chloride - salt is added to precipitate the soap after
saponification
 Pentasodium pentetate - prevents minerals such as calcium and
magnesium in hard water from binding to the soap and affecting
the foaming and cleaning performance.
 pentaerythrityl tetra-di-t-butyl hydroxyhydrocinnamate -
antioxidant that inhibits reactions promoted by oxygen that could
cause the unsaturated fats in the soap to become rancid.
 D&C green No. 8, FD&C Green No. 3 - green dyes
 Titanium dioxide - white pigment that serves to give a lighter
color to the soap and modify the color obtained from the use of
the green dyes.

5. Working mechanism of soaps
 Soap acts as an emulsifier, which makes it an
excellent cleansing agent. An emulsifier is capable of
dispersing one liquid into another immiscible liquid.
Soap molecule has an ionic and non-ionic part, the
non-ionic part (hydrocarbon chain) doesn’t naturally
mix with water, soap can suspend oil/dirt in such a
way that it can be removed.
 The organic part of a natural soap is a negatively-
charged, polar molecule. Its hydrophilic (water-loving)
carboxylate group (-CO2) interacts with water
molecules via ion-dipole interactions and hydrogen
bonding. The hydrophobic (water-fearing) part of a
soap molecule, its long, nonpolar hydrocarbon chain,
does not interact with water molecules. The
hydrocarbon chains are attracted to each other by
dispersion forces and cluster together, forming
structures called micelles.

6. Working mechanism of soaps cont..
 n these micelles, the carboxylate groups form a
negatively-charged spherical surface, with the
hydrocarbon chains inside the sphere. Because
they are negatively charged, soap micelles repel
each other and remain dispersed in water.
 Grease and oil are nonpolar and insoluble in
water. When soap and soiling oils are mixed, the
nonpolar hydrocarbon portion of the micelles
break up the nonpolar oil molecules. A different
type of micelle then forms, with nonpolar soiling
molecules in the centre. Thus, grease and oil and
the ‘dirt’ attached to them are caught inside the
micelle and can be rinsed away.


7. Applications of soaps
 Used as skin cleaner
 Used in laundry for cleaning textiles.
 Drive nails easier with less risk of splitting the wood,
by first rubbing it on the nail shank.
 Keep garden bugs off plant leaves by mixing it with
water and spraying the solution on the leaves'
undersides.
 Soap and water works as well as anything to repel
fleas, and the fleas will drown in the water.
 Soap is alkaline, and combined with some minerals
such as baking soda, borax, or washing soda, it
succeeds in a number of different all-purpose
cleaning tasks
 Remove wallpaper glue by mixing with warm water
and sponging it on the walls.

8. Health risks associated with soap
making industry
 There are three main ingredients in plain soap - oil or fat, lye (or
alkali) and water. Lyes are extremely caustic. They cause burns
if splashed on the skin and can cause blindness if splashed in
the eye. If drunk, they can be fatal. Care is needed when
handling lyes. Because of these dangers, keep small children
away from the processing room while soap is being made.
 You should always take precautions when handling these
materials as they are dangerous. Be especially careful when
adding them to cold water, when stirring lye water, and when
pouring the liquid soap into moulds. Lyes produce harmful
fumes, so stand back and avert your head while the lye is
dissolving. Do not breath lye fumes. It is worth investing in a pair
of rubber gloves and plastic safety goggles. You should also
wear an apron or overalls to protect your clothes. If lye splashes
onto the skin or into your eyes, wash it off immediately with
plenty of cold water.
 When lye is added to water the chemical reaction quickly heats
the water. Never add lye to hot water because it can boil over
and scald your skin. Never add water to lye because it could
react violently and splash over you.

9. Reference
 http://www.worldofchemicals.com/445/chemistry-
articles/how-soaps-really-work.html