UNIT 2 : Soaps, Detergents and Emulsions Flashcards
How are soaps made?
We add Sodium Hydroxide to a fatty acid and are left with water and a fatty acid which has an Na+O- group (soap) instead of an OH group
What do we add to the reaction to make a soap?
Sodium Chloride
Why do we add Sodium Chloride to the reaction to make a soap?
To ensure that all of the unstable fatty acid molecules have a Na+O- group bonded to them
What happens to the chloride ions once all of the soap molecules are created?
They just float around in the water
What ion, other than Na+, is used in soaps often?
K+ (from Potassium Hydroxide)
What are soaps in simple terms?
Salts of fatty acids
What is meant by the term hydrophyillic?
A substance/molecule which is attracted to water and it dissolves in polar solvents
What is meant by the term hydrophobic?
A substance/molecule which repels water
What part of the soap molecule is hydrophyllic?
The -COO group
What part of the soap molecule is hydrophobic?
The long carbon chain (“tail”)
How does soap clean things?
When in water, the soap molecule’s “tail” goes into the grease molecule, while the “head” and positive ion stays outwith the grease. This then lifts off of the surface in small ball like molecules and the ion detaches from them
What are the small ball like molecules called?
Micelles
What causes the small ball like molecules to suspend in water?
The repulsion of the negatively charged heads
What is an emulsion?
When two liquids are suspended in each other by the repulsion of their negatively charged heads
What are detergents made of?
Crude oil
When would we use a detergent instead of a soap?
For tougher stains
What do detergents work in a similar way to?
Soaps
What is the difference between soaps and detergents?
Detergents don’t cause an insoluble precipitate (scum) in the same way a soap would
What is similar between soaps and detergents?
They both have hydrophobic and hydrophilic parts
What are biological detergents (enzyme detergents) used for?
Blood or sweat etc
How are biological detergents made?
Naturally
Where and why are emulsifiers used?
In food to separate oil and water and thus, prevent food spoilage
How are emulsifiers for use in food consumption commonly made?
By reacting edible oils with glycerol to form molecules in which there are either on or two fatty acid groups compared to the usual three
In emulsifiers, what part of the molecule is hydrophobic and what part is hydrophylic?
The OH groups are hydrophilic, and the fatty acid chains are hydrophobic
