C1

Gateway science suite - Chemistry B J264

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Fossil fuels

Fossil fuels - 

Finite resourceWill run out one day

Non renewable - Being used up faster than they are being formed

Replacements need to be found 

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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 

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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.

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Cracking

Process that turns large arkane molecules into smaller arkane and arkene molecules.

Cracking also helps oil manufacturers match supply with demand. 

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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.

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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. 

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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. 

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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 

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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

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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
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Protein

Protein molecules permanently change shape when cooked/

called denaturing

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Esters

alcohol + acid = ester + water

Esters are used to make perfumes

A perfume must:

be non toxic 

not irritate the skin

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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
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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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