Unit 2(d) Soaps, Detergents, Emulsions Flashcards
What are soaps?
Soaps are the salts of fatty acids
How are soaps made?
Alkaline hydrolysis of fats and oils
What are the 2 sections which make up soaps?
Hydrophilic head (carboxyl group with hydrogen replaced by metal ion), hydrophobic tail (long alkyl covalent chain)
What are some advantages of soaps?
- Natural from vegetable oils and animal fats
- Naturally alkaline so prevent microbial growth
What are some advantages of detergents?
-Do not form insoluble scums in hard water areas
What is hard water?
Water where calcium ions and magnesium ions are present
What do soaps and detergents have in common?
They are both surfactants (clean by reducing water tension)
Same cleaning action
What other ions can be used in the manufacture of soaps?
Potassium hydroxide (KOH)
How do soaps and detergents clean?
- Hydrocarbon tail dissolves in grease
- Heat and agitating breaks grease loose
- Negative charges repel so grease does not recombine
- Emulsion formed
What is an emulsion?
Small droplets of one liquid dispersed in another liquid
What are the two phases involved in emulsions?
Dispersed phase and continuous phase
What are the two types of emulsion?
- Oil in water emulsion
* Water in oil emulsion
What are some uses for emulsions?
Foods, cosmetics, paints, photographic film
Why do emulsions tend to have a cloudy appearance?
Light scatters as it passes through emulsions
What is an emulsifier?
A substance which stabilises emulsions, stopping them separating out
