chemistry soaps and detergents

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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