CbD - Fats and oils Flashcards
What type of molecule are fatty acids?
Carboxylic acids.
What does saturated mean?
Single bonds only
What does unsaturated mean?
Contains 1 or more double bonds.
Structure of fatty acids
Long hydrocarbon tail with a carboxylic acid group at the end.
What can you use to distinguish between saturated and unsaturated fatty acids?
Bromine water
How can bromine water be used to distinguish between saturated and unsaturated fatty acids?
Double bonds (unsaturated) - the solution will decolourise (orange to colourless).
What are triglycerides?
Triesters of glycerol and fatty acids.
How are triglycerides made?
By reacting glycerol (propane-1,2,3-triol) with fatty acids.
What is the systematic name for glycerol?
Propane-1,2,3-triol
Through what reaction are triglycerides made?
Condensation (the three -OH groups on the glycerol molecules link up to the fatty acids - water is eliminated).
What state are fats and oils at room temperature?
Fats = Solid Oils = Liquid
Another name for triglyceride?
Triester
What are carboxylic acid residues (properties)?
- Usually unbranched hydrocarbon chains.
- Usually an even no. of carbon atoms (up to 24, often 16 or 18.
- Can be saturated or unsaturated.
- Often not the same on each of the 3 ester links.
What do the properties of fats and oils depend on?
Carbon chains of the carboxylic acid residues.
What make carboxylic acid residues hydrophobic?
Long non-polar hydrocarbon chains stop the substance mixing with water.
What affects the melting point of oils (and fats)?
Lower melting point of oils related to higher degree of unsaturation.
Why do oils have a low melting point?
More double bonds (unsaturated) so Id-Id bonds weaker as chains can’t get as close together.
How do you hydrolyse the ester?
Heat the ester with c.NaOH to make alcohol and sodium salt.
What is a ‘residue’?
Something that has reacted.
