Detergents are surfactant which works like soap but is not affected by hard water. The amphiphilic nature of detergent allows the removal of oil and grease from a surface when mixed with water. This is due to the polar (hydrophilic) and non-polar (hydrophobic) nature working together to mix oil/grease which are hydrophobic compounds with water.
As most of our smart Berry Readers would have guessed it, this post, Part 2 of Berry Berry Easy short notes on Chemicals of Consumers in SPM Chemistry for Form 5 students is all about detergents. Learn the most important knowledge required to understand (minimum level) detergents for SPM Chemistry examinations.
[Tips: For those who do not know about hard water as some books neglect to explain, hard water is water with high mineral content especially calcium and magnesium ions. It affects industrial processes more than it affects human health. More importantly, do not assume that soap is the same as detergent. They are similar but have many fundamental differences which will be explain in future posts.]
SPM Chemistry Form 5 Notes – Chemicals for Consumers (Part 2)
- Detergent = sodium salt of sulphonic acid
- Alkalis react with sulphonic acid –> detergent
- Common detergent: sodium alkyl sulphate & sodium alkylbenzene sulphonate.
- Detergent preparation: 2 processes – 1. Sulphonation. 2. Neutralisation.
- Sulphonation: Petroleum fraction (long chain hydrocarbon compounds) converted into sulphonic acid with the present of concentration sulphuric acid. Water molecule is removed.
- Neutralisation: sulphonic acid neutralised with sodium hydroxide to form detergent (water molecule is formed).
- Other type of detergents: 1. Anionic detergent (dishwashing liquid detergent). 2. Cationic detergent (hair conditioner). 3. Non-ionic detergent (car washing detergent).
This marks the end of this post. In the next post, Part 3 on the series of notes on Chemicals for Consumers for SPM Chemistry Form 5 by Berry Berry Easy will be focussed on the cleansing actions of soap and detergent. Do stay tuned.