Unit 2 - Alcohols, Carboxylic Acids, Esters, Fats and Oils, Soaps, Emulsifiers, Detergents Flashcards
What is an addition reaction?
A reaction where 2 small molecules join to form one large molecule.
C=C double bond breaks to allow more atoms to add on.
What is the general formula for a reaction between an alkene and hydrogen?
Hydrogenation
Alkene + Hydrogen -> Alkane
What is hydrogenation?
An addition reaction where hydrogen is added.
What is bromination?
An addition reaction where bromine is added.
What is the general formula for a reaction between an alkene and bromine?
Bromination
Alkene + Bromine -> Bromoalkane
What is hydration?
An addition reaction where water is added.
What is the general formula for a reaction between an alkene and water?
Hydration
Alkene + Water -> Alcohol
What is an isomer?
Molecules with the same molecular formula but different structural formula.
What is the functional group in an alcohol?
Hydroxyl (-OH)
What is the functional group in a carboxylic acid?
Carboxyl group (-COOH)
What is the general formula for a neutralisation reaction between a carboxylic acid and metal oxide?
Carboxylic acid + Mateal Oxide ➡️ Salt + Water
What is the general formula for a neutralisation reaction between a carboxylic acid and metal hydroxide?
Carboxylic acid + Metal hydroxide ➡️ Salt + Water
What is the general formula for a neutralisation reaction between a carboxylic acid and metal carbonate?
Carboxylic acid + Metal Carbonate ➡️ Salt + Water + Carbon Dioxide
How are esters formed?
When an alcohol and carboxylic acid react together.
What is an ester link?
-COO
What are esters used for?
- flavorings in food
- fragrances in air fresheners
- solvents in industrial processes
What is a condensation reaction?
Where 2 molecules react to form 1 molecule and eliminates water.
What is the process for making an ester called?
Esterification/condensation
Is making an ester a reversible reaction?
Yes
What is the general formula of making an ester?
Alcohol + Carboxylic Acid ↔️ Ester + Water
What should you include in a diagram of the process used to make an ester?
- Hot water bath
- A test tube with a carboxylic acid + an alcohol + a catalyst
- Cotton wool in opening of test tube
- Wet paper towel condenser wrapped around test tube
Why must you use a hot water bath instead of a bunsen burner when making an ester?
The products + reactants are flammable.
Name 2 ways you can identify an ester has been made.
- A layer of oil forming in test tube
- Characteristic fruity smell
What is the name of the reaction where an ester is split and broken down by a reaction with water?
Hydrolysis
What conditions is the hydrolysis of an ester carried out in?
- Warm condions
- Usually using an acid/alkali
Why will acid-catalysed hydrolysis never be complete?
It’s reversible.
Why will alkaline hydrolysis result in complete hydrolysis?
The carboxylic acid formed will react with the alkali.
Why are healthy fats and oils an essential part of the diet?
They’re a concentrated source of energy. They are essential for transport and storage of fat-soluble vitamins in the body.
What type of molecules are fats and oils?
Ester
What origin can fats and oils be?
Animal, vegetable and marine.
What is the chemical name of glycerol?
Propane-1,2,3-triol
How are fats and oils formed?
Glycerol reacting with 3 fatty acid molecules.
How many hydroxyl groups does glycerol have?
3
What are fatty acids?
Carboxylic acid molecules with long saturated or unsaturated carbon chains.
What is the mole ratio of glycerol and fatty acids?
1:3
Do fats have higher m.p than oils?
Yes
Why do fats have high m.p?
They have saturated fatty acids so they can pack closely together. This means they have strong LDFs requiring more energy/heat to break.
Why do oils have low m.p?
They have unsaturated fatty acids so molecules become distorted and cannot pack closely together. This means they have weak LDFs requiring less energy/heat to break.
What is hardening?
Conversion of oils into fats by carrying out hydrogenation (addition of Hydrogen) across the double bonds. Uses a nickel catalyst.
What type of catalyst does hardening use?
Nickel
What is the general word equation for the reversible reaction of the production and hydrolysis of fats/oils.
Glycerol + Fatty Acids ↔️ Fat/Oil + Water
Condensation = ➡️
Hydrolysis = ⬅️
How are soaps formed?
Boiling fats and oils with sodium/potassium hydroxide solution. The alkali firstly catalyses the hydrolysis reaction and then neutralises the fatty acid to form their sodium/potassium salts.
What are soaps?
Salts formed by the hydrolysis of fats and oils using an alkali.
What is the structure of a soap molecule?
A long covalent tail and a carboxylate head.
Describe the traits of a soap molecules ‘tail’.
- Covalent
- Long hydrocarbon chain
- Non-polar
- Oil-soluble
- Not soluble in water
6.Hydrophobic
Describe the traits of a soap molecules ‘head’.
- Ionic
- Carboxylate group
- Polar
- Water-soluble
- Not soluble in oil
6.Hydrophyllic
How does soap clean?
- Soap and water mix
- Covalent tail dissolves in grease and ionic head dissolves in water.
- Grease breaks up into ‘globules’.
- Negatively charged globules repel each other.
- Globules are attracted to water and are washed away.
What happens when soaps are used with hard water?
A white precipitate called scum is formed.
Do detergents form scum?
No
What is the structure of a detergent molecule?
A long hydrocarbon tail and a sulfanate group (SO3-)
What do emulsifiers do?
Prevent polar and non-polar liquids from seperating. They form an emulsion
What is an emulsion?
Small droplets of one liquid dispersed through another.
Name a food that contains emulsifiers.
Egg yolk
How can you recognise an emulsifier?
A polar part and a non-polar part.
True or false: An emulsifier is an example of a mono or diglyceride of fatty acids.
TRUE
What is a monoglyceride?
A molecule with one fatty acid group linked to a glycerol backbone. (mono = 1, di = 2…)
