Wonderful Soaps
In the making of soap, a vegetable oil such as palm oil is boiled with a concentrated alkali solution in a reaction known as saponification. The alkali reacts with the oil and breaks it down into glycerol and fatty acids. These fatty acids react with the alkali to form sodium or potassium salt of the fatty acids.
en.wikipedia.org/wiki/File:Soap_bubbles_2.jpg
The Composition of Soap
Soaps are cleansing substances which are widely used in our daily life. Soaps are usually made from plant oils or animal fats. For example, the plant oils used are coconut oil, olive oil, palm oil and others. Each molecule of fat consists of a combination of one molecule of glycerol and three molecules of fatty acids.
Different fats have different fatty acids. The fatty acids can be separated from the glycerol through the hydrolysis process using an alkali as a catalyst. The fatty acid that is produced reacts with alkali to form a fatty acid salt. The alkali used is sodium hydroxide or potassium hydroxide.
The Making of Soap
Image via Wikipedia
Image via Wikipedia
In the making of soap, a vegetable oil such as palm oil is boiled with a concentrated alkali solution (sodium hydroxide solution) in a reaction known as saponification. The alkali reacts with the vegetable oil and breaks it down into glycerol and fatty acids. These fatty acids react with the alkali to form sodium or potassium salt of the fatty acids.
Soap is the sodium or potassium salt of a fatty acid formed. Common salt is then added to the mixture and boiled. Common salt will lower the solubility of soap in water. Hence, the soap is precipitated out. Glycerol is a by-product of the soap-making industry which is very useful. Examples of fatty acids are palmitic acid and oleic acid.
Characteristics of the Component of a Soap Molecule
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A soap molecule is made up of two parts a) a hydrocarbon chain which is long and bonded by covalent bonds. It forms the tail of the molecule b) a head part at the end of the hydrocarbon chain which is ionic.
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The head part of the soap molecule is ionic and is soluble in water (hydrophilic). The tail part of the molecule is only soluble in organic substances such as oil or grease. It is hydrophobic. Thus, the soap molecule is soluble in both water and oils. When soap is mixed with water, the soap molecules decompose to form sodium ions which are positively charged and soap ions which are negatively charged.
The Cleansing Action of Soap Molecules
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When an oily or greasy cloth is immersed in soapy water, the surface tension of the water is lowered due to the soap. This allows the surface of the cloth to be wet with water. The hydrophobic tail end of the soap molecule buries itself in the grease or dirt, while the hydrophilic head end remains attracted to water. The two ends get pulled in opposite directions but water ‘wins’ the tug-of-war, resulting in the grease being pulled off from the surface and getting carried away.
Image by certified su via Flickr
The grease that has been pulled off is surrounded by soap molecules and forms oil droplets. Lather (foamy bubbles) produced help to float the grease or oil droplets in water. The oil droplets in the soap water form an emulsion solution. As each ionic head is charged (negatively), the oil droplets repel each other. This prevents the droplets from combining again. The oil droplets are then removed with the soap solution.
When soap dissolves in hard water, the soap molecules react with calcium and magnesium ions in hard water and form a grey, sticky insoluble ‘scum’. The action of hard water on soap weakens the cleansing action of soap and causes more wastes of soap. Synthetic detergents are made by mixing oil with concentrated sulphuric acid. Detergents form lather in hard water. Modern washing powders contain detergents and soap. Sodium carbonate (washing powder) is added to powders to soften hard water. Carbonate bonds with the calcium or magnesium, leaving soap free to remove the dirt and grease.
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However, the use of synthetic detergents can cause a pollution problem because synthetic detergents are not biodegradable.
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17 Responses to “Wonderful Soaps”
On July 20, 2009 at 1:40 am
Great, informative article, Mr Ghaz.
On July 20, 2009 at 1:49 am
Hey friend, this article could be very helpful to those desiring to engage in small-scale soap business.
On July 20, 2009 at 1:52 am
This is unique! Great piece again, thanks and have my liked it.
On July 20, 2009 at 3:16 am
You have made what I thought would be a dull subject very interesting – cool article!
On July 20, 2009 at 3:55 am
Your topic has cleansing powers. It feels like having a cool bath. A wealth of information in a shower.
On July 20, 2009 at 4:28 am
Now this is a refreshing article. I love soaps and more soaps! I will put thisin my library and TU to. Thanks.
On July 20, 2009 at 5:40 am
Wonderfully executed article!They are always well written,informative and interesting.You clearly spend a lot of time on them!!
On July 20, 2009 at 5:52 am
pretty cool information about something we take for granted!!
On July 20, 2009 at 7:17 am
I’ve been thinking of making soap for my family, but hesitated because I didn’t really understand how it worked. You’ve provided the missing link. Thanks.
On July 20, 2009 at 11:49 am
It looks like a lot of trouble but you make it very tempting, Mr. G =]
On July 20, 2009 at 12:49 pm
Very unusual article and very interesting!
On July 20, 2009 at 12:51 pm
Very interesting!
On July 20, 2009 at 1:40 pm
Thank you for this post. I have been interesting in soap making for sometime. I will return to this post in the future. Very nice.
On July 20, 2009 at 10:07 pm
Your artciles are always infornative and well written.
On July 20, 2009 at 10:19 pm
This makes me think that before inventing the soap, perfume was used more
On July 22, 2009 at 9:23 pm
Interesting as usual, so many different types and styles of soap now days.
On August 10, 2009 at 11:31 pm
very interesting read as always. Thanks a lot
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