Unit 2 - Nature's Chemistry (Soaps, Detergents, and Emulsions) Flashcards
(14 cards)
What are soaps and how are they made?
A sodium or potassium salt produced during the neutralisation of a fatty acid with an alkali/the alkaline hydrolysis of fats and oils. Fat molecules are hydrolysed when they are heated with sodium hydroxide or potassium hydroxide:
Fat/oil + sodium hydroxide –> soap + glycerol.
What are soaps used for?
Removing non-polar substances such as oil or grease.
What structure do soaps have?
- A polar, ionic, negatively-charged head that is hydrophilic (dissolves polar substances such in water).
- A long, non-polar, covalent hydrocarbon uncharged tail that is hydrophobic (dissolves in non-polar substances such as oil or grease).
What happens when agitation occurs (scrubbing/mixing)?
The grease is broken up into small ball-like structures (micelles) and held in suspension in the water by the repulsion of the negatively charged ionic heads.
What are detergents?
A family of compounds that are similar to soaps and work in a similar way. They also contain specific hydrophilic (ionic) and hydrophobic (covalent) parts.
What are detergents used for?
They are most commonly used in our homes when washing clothes, dishes, or as surface cleaners.
In what areas are detergents more useful than soaps at removing oils/grease?
In areas where hard water is present.
What is hard water?
Water that contains high levels of dissolved metal ions.
Why are detergents more useful than soaps in areas where hard water is present?
They don’t form scum with hard water, whereas soaps do.
What is scum?
An insoluble precipitate.
What is an emulsion?
Formed when tiny droplets of one liquid are suspended within another liquid. A mixture of oil and water is a good example of an emulsion.
What are emulsifiers?
Chemicals that prevent non-polar and polar substances from separating into layers, which causes food to spoil.
Which foods contain emulsifiers?
Bread, ice-cream, sauces, and biscuits.
How are emulsifiers formed?
They are made by reacting edible oils with glycerol.
