Notesale: Turn your study into money

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Chemistry Chapter 5 & 6 Revision
5
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The process
takes place at an oil refinery in a steel vessel called a cracker
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The vapour is then either passed over a hot catalyst or mixed with steam
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The hydrocarbons are cracked as thermal decomposition reactions takes place
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Cracking produces saturated hydrocarbons which are used as fuels and unsaturated
hydrocarbons (called alkenes)
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However, if you mix it with an alkane
then it will not change colour at all, or it will change very little (orange-yellow colour)
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Tip:
Alkanes are saturated
Alkenes have a double bond = (equals)

5
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

Plastics are made up of huge molecules made from lots of small molecules joined together
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The huge molecules are called polymers (Mono
means ‘one’ and poly means ‘many’)
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Polymers are large molecules made when monomers (small reactive molecules) join together
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Carbon Cost:
A carbon price is a cost applied to carbon pollution to encourage polluters to reduce the
amount of greenhouse gas they emit into the atmosphere
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5
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Making
plastics with starch granules in their structure help the microorganisms break down a plastic
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We can make biodegradable plastics from plant material such as cornstarch
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Recycling plastics and sorting them into different types to make new products, saves energy
and resources
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However, the use of a food crop like corn to make plastics raises the same problems as using
biofuels
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5
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The chemical
formula of Ethanol is C2H5OH
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Making Ethanol by Fermentation:
o

Ethanol for drinks is made by the fermentation of sugar from plants
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Sugar (glucose) ethanol + carbon dioxide
C6H12O6 2C2H5OH + 2CO2

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Ethanol can be made from ethene reacting with steam in the presence of a catalyst
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Using ethene to make ethanol needs non-renewable crude oil as its raw material whereas
fermentation uses renewable plant material
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Ethene gas can react with steam to make ethanol
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The
reaction is reversible so ethanol can break down back into ethene and steam
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However, ethene to make
ethanol relies on crude oil which is a non-renewable resource
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Large-scale industrial uses for
fermentation will be a big problem, because we will need crops, which take land,
which ruins wildlife and could harm the environment
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1 Extracting vegetable oil
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2

Vegetable oils can be extracted from plants by pressing or distillation
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Farmers collect seeds from rape plant (example)
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The seeds are taken to a factory to be crushed and pressed to extract their oil
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The impurities are removed from the oil
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Then it is processed to make more useful products
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Farmers collect lavender plants (example)
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The plants are taken to a factory to be extracted by distillation
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The plants are put into water and boiled
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The oil and water evaporate together and are collected by condensing them
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Vegetable oils provide nutrients that we need every day
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This makes them useful for foods and sources of biofuels, such as biodiesel
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However
all vegetable oils have molecules which contain chains of carbon atoms
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We call these
unsaturated oils
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Unsaturated oil + bromine water (orange) colourless solution
Saturated oil + bromine water (orange) orange-yellow (orange) solution (no reaction)

6
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However, this
increases the energy content of foods compared with cooking in boiling water
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This makes them solids at room temperature, which are suitable for spreading
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The hydrogen adds onto C = C
bonds in the vegetable oil molecules
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6
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

3

An emulsion is a mixture of oil and other things (like water, egg and etc)
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The ‘tail’ is a long
hydrocarbon chain
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The ‘head’ is a group of
atoms that carry a charge
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The ‘tails’ dissolve in oil making tiny droplets
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As like charges repel, the oil
droplets repel each other
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Recap:
o
o

Oils and water can be dispersed (spread out) in each other to produce emulsions
which have special properties
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o

Emulsifiers stop oil and water from separating out into layers
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o

Vegetable oils are high in energy and provide nutrients
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o

4

Oils do not dissolve in water
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This makes
fatty foods more palatable and tempting to eat

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