chemistry soaps and detergents
TRANSCRIPT
SOAPS AND DETERGENTS
SOAPSSoap is a salt of fatty acidsMost commonly Sodium and
Potassium salts are long chained in soaps
Soap is a water soluble Base
PREPARATION OF SOAPSoaps are obtained by heating
vegetable oil or animal oils and fats in presence of a strong alkaline solution
Fats and oils are mainly composed of three molecules of fatty acids attach to a single molecule of glycerol (triglycerides)
The alkaline solution, which is often called lye, brings about a chemical reaction known as saponification.
During this reaction, crude soap will be formed with the by-product glycerin which is a softening agent
FAT or OIL + NaOH --------> SOAP + GLYCERIN
Make your FANCY soap !!! Take about 20ml of castor oil / linseed
oil in a beaker and add 30ml of 20% NaOH solution
Heat it with constant stirring for a few minutes till it thickens
Add 5-10 g of NaCl to this and cool Filter the mixture using a filter paper Now the soap formed can be cut into
various fancy shapes . Perfumes can also be added
SOAP MOLECULEA soap molecule contains two ends having different
propertiesHYDROPHILIC : Dissolves in water ( water-loving ) It keeps away from hydrocarbonsHYDROPHOBIC : Grabs onto oil , dirt and hydrocarbons It keeps away from water ( water-fearing ) or ( water – repelling )
MICELLES Micelles are lipid molecules that
arrange themselves in a spherical form inside aqueous solutions.
The formation of a micelle is a response to the nature of fatty acids
It will have a unique formation
In this formation , the hydrophobic tails are in the interior of the cluster and hydrophilic ends are on the surface of the cluster
EFFECT OF SOAP IN CLEANING• Soap in the form of micelle will be able to clean dirt
from our clothes and other materials• In a micelle , the oily dirt will be collected in the
centre
• THE MICELLES WILL REMAIN IN THE SOLUTION AS A COLLOID AND WILL NOT JOIN TOGETHER BECAUSE OF ION-ION REPULSION
• SO THE DIRT CAN BE RINSED OFF EASILY• THEY APPEAR CLOUDY AS THEY ARE LARGE
ENOUGH TO SCATTER LIGHT
ADVANTAGES AND DISADVANTAGES OF SOAP
Soaps are AntibacterialAs they are basic , they neutralize the excess acidThey are bio-degradable
Some soaps can be harmful to the skin They are not suitable in hard waterHave weak cleansing properties than detergents
SCUM• Most of the people would have observed
some insoluble substance that remains after bathing
• This is known as scum and is caused due to the reaction of soap
with calcium and magnesium salts causing the hardness
DETERGENTSThe problem of scum can be
overcome by another class of compounds called DETERGENTS
Detergents are generally ammonium or sulphonate salts of long chain carboxylic acids
It is normally a surfactant which has cleaning properties in dilute solutions
ADVANTAGES OF DETERGENTSThey are more soluble in hard waterThey are available in both powders and
concentrated solutionsThey are commonly used to make shampoos
and products for cleaning clothes
S . ANUSH KARTHIK &
V . ARJUN
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