C1
Gateway science suite - Chemistry B J264
- Chemistry
- Crude oil, cracking and hydrocarbonsProperties of hydrocarbonsPolymersPaints and oils
- GCSE
- OCR
- Created by: ruaridhblackett
- Created on: 04-06-17 01:31
Fossil fuels
Fossil fuels -
Finite resource - Will run out one day
Non renewable - Being used up faster than they are being formed
Replacements need to be found
Fractional distillation
Crude oil - Mixture of many different types of oil - all hydrocarbons - Made of hydrogen and carbon only
Bitumen has a high boiling point - Bottom of column - Large molecules - lots of energy is needed to break the intermollecular forces between the molecules.
Petrol has a low boiling point - Top of column - Smaller molecules - less energy is needed to break the intermollecular forces between the molecules
Problems in extracting crude oil
Transporting oil - Oil slicks - damage birds' feathers - cause their deaths
Political problems - UK relying dependant on oil from politically unstable countries. Can set high prices and cause problems for the future.
Cracking
Process that turns large arkane molecules into smaller arkane and arkene molecules.
Cracking also helps oil manufacturers match supply with demand.
Choosing fuels
Governments are concerned because of the increasing carbon dioxide emissions.
Many governments have pledged to try and cut carbon dioxide emisions
As the population increases, so does the amount of fossil fuels burned.
Combstion
Complete combustion - occurs when a hydrocarbon fuel burns in plenty of oxygen. It produces carbon dioxide and water.
-More energy is released during complete combustion
Incomplete combustion - occurs when a hydrocarbon fuel burns without sufficient oxygen. It produces carbon monoxide and water. OR carbon and water.
-A toxic gas (carbon monoxide) and soot (carbon) are produced.
Clean air
Clean air -
78% Nitrogen
21% Oxygen
0.035% CO2
The % of CO2 in the air has increased slightly because:
Deforestation - As more rainforests are cut down - less photosynthesis takes place.
Increased population - more fossil fuels burned.
Hydrocarbons
ALKANES - SINGLE COVALENT BOND
ALKENES - DOUBLE COVALENT BONDS between carbon atoms
Bromine - test for alkene - orange bromine water - added to an alkene - turns colourless
Saturated compound - single covalent bond . Alkanes are saturated
Unsaturated - double covalent bond - Alkenes are unsaturated
Polymerisation
Many alkene monomers react to give a polymer.
Polymer - long chain, two brackets, n
Double bond in the monomer to break and 2 carbon atoms are formed. - High pressure w/ catalyst
Breathable polymers
Nylon is tough, lightweight, keeps out water, does not let water vapour through. Sweat condences.
GORE TEX - breathable and waterproof - made of ptfe #
DISPOSING POLYMERS
- Burning produces toxic gases, wastes crude oil
- Recycling is difficult - it is hard to sort polymers
- Dissolving and biodegradable polymers are being developed
Protein
Protein molecules permanently change shape when cooked/
called denaturing
Esters
alcohol + acid = ester + water
Esters are used to make perfumes
A perfume must:
be non toxic
not irritate the skin
colloids + paints
- Paint is a colloid - the particles are mixed and dispersed with particles of a liquid but are not dissolved
Colloids:
- Paint is a colloid - the particles are mixed and dispersed with particles of a liquid but are not dissolved
Paint drying:
- Emulsion paints are water based and dry when the solvent evaporates
- Oil paints dry when the solvent evaporates and the oil is oxidised by the atmospheric oxygen
Pigments
Phosphorescent pigments:
- These glow in the dark because they absorb and store energy, which is released as light over time
- Phosphorescent paints are better than radioactive paint because of safety
Thermochromic pigments:
- Thermochromic pigments change colour at different temperatures and can be combined with acrylic paints for different colours
- Uses include baby spoons and cups to show when they are hot
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