Chemistry of Toiletries Flashcards
What does a soapless detergent have
a sulfonate head instead of a carboxyl head
How are soaps made ?
-Soaps are produced by the alkaline hydrolysis of edible fats and edible oils. Hydrolysis produces three fatty acid molecules and one glycerol molecule. The fatty acid molecules are neutralised by the alkali, forming water-soluble, ionic salts called soaps.
-Soap is the sodium salt of a fatty acid.
Describe the cleaning action of soaps
Soaps can be used to remove non-polar substances such as oil and grease.
Soap ions have long non-polar tails, readily soluble in non-polar compounds (hydrophobic), and ionic heads that are water-soluble (hydrophilic).
The hydrophobic tails dissolve in the oil or grease. The negatively-charged hydrophilic heads remain in the surrounding water.
Agitation causes ball-like structures to form. The negatively-charged ball-like structures repel each other and the oil or grease is kept suspended in the water.
What is an emulsion
An emulsion contains small droplets of one liquid dispersed in another liquid.
An emulsifier can be used to prevent non-polar and polar liquids separating into layers.
How is an emulsifier made ?
Emulsifiers for use in food can be made by reacting edible oils with glycerol.
In the molecules formed, only one or two fatty acid groups are linked to each glycerol backbone.
The hydroxyl groups present in the emulsifier are hydrophilic whilst the fatty acid chains are hydrophobic.
The hydrophobic fatty acid chains dissolve in oil whilst the hydrophilic hydroxyl groups dissolve in water, forming a stable emulsion.
