2.4 Esters, Fats and Oils Flashcards
How are esters made
Condensation reaction between and alcohol and a carboxylic acid
What is a condensations reaction
Two or more small molecules joining to form a larger molecule with the elimination of a smaller molecule e.g. water
What is hydrolysis
Breaking down of larger molecules into smaller molecules by reaction with water
What is always formed when an ester is made
Water
How is the water formed when making an ester
The alcohol loses a -H and the acid loses an -OH
How do you name an ester
The alcohol first the acid second e.g. Ethanol + Propanoic acid > ethyl propanoate + water
Give three uses for esters
Flavourings in food, Perfumes and Solvents
Is an ester polar or non-polar
non-polar
What alkali is used for the hydrolysis of an ester
Sodium hydroxide
What method of hydrolysis is used to hydrolyse an ester
Heating under reflux
What are the steps for hydrolysis of an ester
- Condenser 2. Distillation (the salt and the alcohol formed can be separated because they have different boiling points)
What are the products if hydrolysis using an alkali
An alcohol and the salt of the carboxylic acid
What are fats and oils an example of
Esters
What is the alcohol present in fats and oils
Propan-1,2,3-triol (Glycerol)
Why can glycerol be called a trihydric acid
Because it has 3 -OH groups
What is the make up of a fat or oil
! mole Glycerol and 3 moles of long chain fatty acids
What is the catalyst used during hydrolysis of a fat or oil
Sulphuric acid
What is the products of hydrolysis of a fat or oil
1 glycerol molecule and 3 fatty acids
Are oils saturated or unsaturated
Unsaturated
Why are oils unsaturated
Due to the presence of at least 1 carbon to carbon double bond
What state are oils in at room temperature
Liquid
Why do oils have lower melting and boiling points
C=C bonds are not flexible and so molecules cannot pack closely together, this means van der Waals are weak oil is liquid at room temp
Why are fats saturated
They only contain carbon to carbon single bonds
Why do fats have higher melting and boiling points
C-C are flexible and pack closely together so have larger van der Waal forces and at solid at room temp
What is the catalyst used in the hydrogenation of oils
Nickel
What happens during hydrogenation of an oil
Addition of hydrogen ‘Hardens’ the oil and turns it into a saturated fat meaning the molecules can pack more closely together
Which of oils and fats are considered to be healthier
Oils
