Chemicals for Consumers consist of many everyday product used in society such as soap, detergent, alcohol, food additives, insect sprays, paints, petrol, medicines and many others. The understanding of the use and associated risks involving the chemicals contained in the consumer products are crucial to reduce the potential harmful effects of chemicals for consumers.
In this Part 1 of notes by Berry Berry Easy in the chapter of Chemicals for Consumers for SPM Chemistry Form 5 students, the focus will be on soap, both solid and liquid soap. Soap has been discovered since ancient times by various civilisations through a process called saponification. Unbeknownst to them at that time, “soap” is one of the earliest organic chemical and “saponification” is one of the earliest known organic chemical reactions, respectively. In the ancient days of saponification, soap were produced from the boiling of animal fat with lye. Nowadays, it is mainly done industrially with vegetable fat with sodium hydroxide under heated conditions (followed by other precipitation and purification processes). Read all about the basic of soaps in this post. It’ll be great help to complete your SPM folio for the chapter of Chemicals for Consumers.
[Tips: Hazardous chemicals are present in various consumer products such as deodorisers, household cleaners, textiles, body care products and even toys. They can include substances such as alkylphenols, bisphenol-A, ethoxylates, musks, organotin compounds and phthalates. So it pays to know what chemical is used in typical industrial processes. While not a study tip useful for exams, but keeping yourself healthy in the long-term is definitely more important.]
SPM Chemistry Form 5 Notes – Chemicals for Consumers (Part 1)
- Soap = sodium salts (RCOO-Na+) / potassium salts (RCOO-K+) of long-chain fatty acids
- Alkalis react with fatty acids –> soap
- Fatty acids = animal fats or vegetable oils
- Soap preparation: hydrolysing fats or oils under alkaline condition
- Saponification – alkaline hydrolysis
- Saponification process – boiling fats / oils with concentrated sodium hydroxide solution or concentrated potassium hydroxide solution to produce glycerol + salts of fatty acids (soap)
- Saponification steps: 1. Hydrolysis of fats / oils –> glycerol + fatty acids. 2. Neutralisation of fatty acids + concentrated alkali –> soap + water
- Overall equation: Fats / oils + alkali –> glycerol + soap
- Sodium chloride – reduces the solubility of soap in water
|Liquid soap||Solid soap|
|Sodium hydroxide + saturated oils (coconut oil)||Potassium hydroxide + unsaturated oil (sunflower oil / olive oil)|
|Uses: bathing purposes||Uses: shaving cream|
The next part, Part 2 of notes from Berry Berry Easy on Chemicals for Consumers for SPM Form 5 Chemistry will be on detergent.