Natures Chemistry Flashcards
What are saturated compounds
Only contain single carbon to carbon bonds
What are unsaturated compounds
Contain atleast one carbon to carbon double bond
What is the test for unsaturation
The bromine solution test
If a molecule is unsaturated the bromine becomes decolourised
What is a homologous series
Family of compounds with similar chemical properties and a shared general formula
What are isomers
Compounds with the same molecular formula but different structural formula
What functional groups belongs to the alcohols (plus general formula)
Hydroxyl functional group = -OH
General formula = CnH2n + 1OH
Whats the difference between primary, secondary and tertiary alcohols
Primary alcohols have one carbon (2 H atoms) bonded directly to C-OH whilst secondary alcohols have two carbon atoms directly bonded to the C-OH and lastly tertiary alcohols which have three carbon atoms directly bonded to the C-OH
Are alcohols polar
Yes! Hydrogen bonding exists between the molecules
What is miscibility
How easily a liquid solute dissolves in a liquid solvent (or how well two liquid substances mix)
What functional group do the carboxylic acids contain ( plus general formula)
Carboxyl functional group = -COOH
General formula = CnH2n+1COOH
What products do u get when a metal oxide and a carboxylic acid react
Salt and water
What products do u get when a metal hydroxide and carboxylic acid react
Salt and water
What products do u get when a metal carbonate and carboxylic acid
Salt and water and carbon dioxide
What functional group do esters contain
An ester link = o-c=o
How do esters form
A condensation reaction involves two molecules joining together with the elimination of a small molecule. Im this case an alcohol and carboxylic acid (water and ester form)
What chemical is necessary to add when making esters
Concentrated sulfuric acid - acts as a catalyst and increases rate of reaction
In an ester forming experiment what is added to the mouth of the test tube
A damp paper towel to act as a condenser
What is hydrolysis
When a molecule reacts with water to break down smaller molecules
What happens when an ester is hydrolysed
It reacts with water in the presence of sodium hydroxide. The ester link is broken producing the parent alcohol and carboxylic acid
Name uses of esters
> Used as flavourings and fragrances
Esters have pleasant, fruity smells
Used as solvents for non-polar compounds that do not dissolve in water
How are fats and oils formed
Edible fats and oils are esters. Glycerol and fatty acids are the two chemicals involved in forming fats and oils
What is the systematic name for glycerol
Propane-1,2,3-triol
What are carboxylic acids known as in fats and oils
Fatty acids - they cam be saturated or unsaturated straight chain carboxylic acids (usually long chains)
How are fats and oils formed
The condensation of glycerol and 3 fatty acids
Explain fully why edible oils have a lower melting point than edible fats
Oils are more unsaturated as they contain double bonds which cause kinks in chains of fatty acids. These kinks mean the molecules cant pack closely together and results in weaker Van Der Waals forces of attraction
Explain fully why edible fats tend to have higher melting points than edible oils
Fats tend to be saturated which mean their carbon chains are are long and straight. These chains can pack closely together and therefore have stronger intermolecular forces and higher mpts
How do you distinguish between edible fats and oils
Use bromine solution
Unsaturated oils will quickly decolourise bromine. As the number of C-C double bonds increase so too does the volume of bromine required to decolourise it
Why are fats and oils important for the body
They are a concentrated source of energy. They are essential for the transport and storage of fat-soluble vitamins in the body
How are soaps formed
They are produced by the alkaline hydrolysis of edible fats and oils. This produces 3 fatty acid molecules and one glycerol molecule
When using sodium hydroxide in alkaline hydrolysis aren the original three fatty acids formed
No! The fatty acids are neutralised by the alkali. Soaps are therefore fatty acid salts
Uses of soaps
> used to remove non-polar substances such as oil and grease
Describe how the structure of soaps allow them to remove non-polar substances
Soap ions have long non polar tails. They are hydrophobic (water-hating)
Soaps have ionic negatively charged heads that are water-soluble
They are hydrophilic (water-loving)
Describe the cleaning action of soaps
Tails dissolvr in oil or gresse and heads remain in water
Agitating the water causes ball like structures to form
How does the greese remain suspended
The negatively charged balls repel each other keeping it suspended
What happens when soap is used in hard water
Produces an insoluble precipitate called scum
(Hard water contains high levels of dissolved metal ions)
What solution stops scum forming in hard water
Soapless detergents - still have hydrophobic tails and hydrophilic heads
What are emulsifiers used for
Used to prevent non polar liquids separating into layers
How are emulsifiers similar to fats and oils
They are similar in the fact they have 1-2 fatty acids and a molecule of glycerol. They are made by reacting edible oils with glycerol
How do emulsifiers differ from fats and oils
Whilst they form ester links with the glycerol backbone, there are still unused hydroxyl groups on the molecule
How do emusifiers work
Hydroxyl groups are hydrophylic and dissolve in water, whilst fatty acid chains are hydrophobic and dissolve in oil forming a stable emulsion
