3.9 Triglycerides

Question 1

What are triglycerides?

Answer 1

fats and oils derived from plants and animals

Question 2

What process formed triglycerides?

Answer 2

Condensation of 1,2,3-propan-tri-ol and various carboxylic acids to form tri-esters

Question 3

Which triglycerides are liquid at RT?

Answer 3

Edible oils
Derived from plants (generally)
Unsaturated triglycerides or fatty acids
Have a lower MP

Question 4

Which triglycerides are solid at RT?

Answer 4

Edible fats
Derived from animals
Have high MP
Saturated triglycerides or fatty acids

Question 5

What are fatty acids?

Answer 5

Also known as carboxylic acids

Question 6

What characteristic are require of fatty acids to form triglycerides?

Answer 6

Even number of carbon between 12 and 20 carbons
NO branching chains
Can be saturated or usaturated

Question 7

Define saturated

Answer 7

Contains no carbon double-bonds

Question 8

Define unsaturated

Answer 8

Contains at least one carbon double bond

Question 9

Define poly-unsaturated

Answer 9

Contains 2 or more carbon double bonds

Question 10

State and explain MP of saturated fats

Answer 10

High melting point
- They have a regular tetrahedral shapeand therefore are able to pack together efficient increasing the density of the molecule

Question 11

State and explain MP of unsaturated fats

Answer 11

Lower melting point and liquid at RT
- carbon-carbon double bonds changes the 3D shape to one of irregularity and thus the fatty acids are unable to pack together efficiently thus lower density

Question 12

How can bromine or iodine be used to determine the degree of unsaturation?

Answer 12

The no. of moles of iodine they turns from brown to colourless per mole of fatty acid will dictate the no. of double bonds present in the particle

Question 13

What are iodine number and how can they be calculated?

Answer 13

The iodine number is the mass of iodine required to unsaturate 100g of particle

Question 14

What process will convert unsaturated fats to saturated fats? state conditions and required substances

Answer 14

Hydrogenation
requires hydrogen 
High pressure
high heat
addition of catalyst

Question 15

What physical property changes will be experience after hydrogenation?

Answer 15

The MP will increase as saturated fats are density due to more regular shape

Question 16

What particles are soaps derived from?

Answer 16

Soaps are derived from fats

Question 17

What is the difference between soaps and synthetic detergents?

Answer 17

Soaps are derived from fats

Synthetic detergents are derived from petroleum compounds (have sulfur)

Question 18

How are micelles formed?

Answer 18

When triglycerides are hydrolysed in alkaline condition the fatty acid forms the carboxylate anion. The carboxylate anion has both a hydrophilic and hydrophobic end. The hydrophobic ends attract the each other to form a micelle.

Question 19

Define hydrophilic

Answer 19

Attracted/likes water

Question 20

Define hydrophobic

Answer 20

Repelled / dislikes water

Question 21

Describe how micelles can be used to remove grease from clothing

Answer 21

First the carboxylate anions will dissociate from the solid soap and subsequently form micelles.

The hydrophobic centre of the micelle will bond with the non-polar grease using dispersion forces. *agitation

The hydrophilic ends will then bond with water and be washed away removing the grease from clothing