Colour by Design - Oils and fats

11 important questions on Colour by Design - Oils and fats

What are oils and fats?

Naturally occurring triesters of propane-1,2,3-triol (glycerol) and long chain carboxylic acids (fatty acids)

What are the features of fatty acids?

- They are the carboxylic acids in fats and oils

- They have an even number of carbons (typically 16 0r 18) in their unbranched carbon chain (these chains can either be saturated or unsaturated)

What can be said about triesters from largely saturated fatty acids? How does this differ from triesters from largely unsaturated fatty acids?

They are solids or fats - the chains are straight = there is better packaging of the molecules resulting in stronger intermolecular bonds 

 

Unsaturated fatty acids = oils = double bonds = kinks in the chains = packed together less tightly  = liquid at r.t.

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What is the difference between the strength of the van der waals between oils and fats?

Fats - strong

Oils - weak

What is another name given to fats and oils? What reaction gives this? What type of reaction is this?

triglyceride 

glycerol + palmitic acid = triglyceride (condensation reaction)

What can oils and fats be hydrolysed by?

NaOH

How can double bonds in a fatty chain be converted into single bonds in a fatty chain?

Hydrogenation using a heated nickel catalyst produces a more saturated solid fat. Not all C=C double bonds are hydrogenated and this gives a spreadable fat which is still polyunsaturated. 

What are the bond angles around the C=C doubled bond in an unsaturated oil?

120 degrees

How does the shape of a saturated triester molecule differ from that of an unsaturated triester molecule?

Saturated triesters are more linear. 

The degree of unsaturation can be determined by measuring the mass of iodine which reacts with 100g of oil or fat. Explain why this is the case.

Each C=C bond reacts with an iodine molecule; the more iodine used the more unsaturated the oil or fat is.

Suggest in terms of intermolecular bonds, why nitrous oxide is readily soluble in fat. 

They have similar intermolecular forces - this like for like intermolecular bonding is the instantaneous dipole induced dipole (there is also slight polarity) 

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