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Electrolysis

Ionic compounds do not conduct electricity when solid because the ions are not free to move

Ionic compounds conduct electricity when molten or in an aqueous solution

Electrolysis is the decomposition of a substance by passing an electric current through it

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Electrolyte

Substance electrolysed

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Anode (electrolysis)

Positive electrode
Non-metal formed here (due to negative ions)
Non-metal loses electrons

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Cathode (electrolysis)

Negative electrode
Metal is formed here, due to positive ions
Metal gains electrons

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Electrolysis of aqueous solutions

A aqueous solution containing ions can be electrolysed

Water has an influence on the reaction

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Negative electrode

Cathode

Hydrogen or a metal formed

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Positive electrode

Anode

Oxygen or a non-metal formed

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Metal more reactive than hydrogen

Hydrogen at cathode

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Metal less reactive than hydrogen

Metal at cathode

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Condensation reactions

Two molecules react -> form a larger molecule with the elimination of a small molecule (water)

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Condensation polymers

Many monomers join together to make a polymer for each pair of monomers that join a small molecule is eliminated (water)

Polyesters (herylene)
Polyamides (nylon)

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Disposing of polymers- landfill

Uses up valuable land, non-biodegradable

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Disposing of polymers- incineration

They release alot of energy when burnt (useful)
Carbon dioxide produced as well as toxic gases

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Disposing of polymers- recycling

Reduces disposal problems
The separation of different polymers is expensive and difficult

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Addition polymers

A long- chain molecule formed by many small monomers joined together

Have a c-c double bond, this breaks allowing monomers to attach together

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Burning fuel in cars

High temperatures means nitrogen + oxygen -> oxides of nitrogen

They dissolve in the air to form acid rain

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Incomplete combustion

Lack of oxygen

Produces carbon monoxide

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Catalytic converters

Carbon monoxide -> carbon dioxide
Oxides of nitrogen -> nitrogen and oxygen

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Cracking

Long-chained hydrocarbons (alkanes) passed over a catalyst
(Silica or aluminium oxide) at 600-700*C

Many short-chained alkanes produced, at least one alkene

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Problems of fractions

Far too many higher boiling point fractions

Not enough of the lower boiling point fractions

Cracking: converting long-chained hydrocarbons -> shorter-chained ones
To make more gasoline

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Refinery gas uses

Bottles gas

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Gasoline uses

Petrol for cars

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Kerosene uses

Fuel for aeroplanes
Central heating boilers
Paraffin small heaters

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Diesel oil uses

Diesel fuel for: buses, lorries, trains, cars

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Fuel oil uses

Fuel for ships, industrial heating

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Bitumen uses

Road surfaces, covering flat roofs

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Factions of crude oil

Refinery gases
Gasoline
Kerosene
Diesel oil
Fuel oil
Bitumen

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Refining of crude oil

Crude oil heated until it is a vapour
Fed into the column at the bottom

Hydrocarbons with very high boiling points immediately turn to liquids and are tapped off at the bottom of the column

The other hydrocarbons rise up the column
As they rise they cool down
They will condense at different heights

Refinery gasses stay S gases and come out of the top of the column

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Crude oil

A mixture of hydrocarbons mainly alkanes

Must be refined before having any use

First step is fractional distillation

Carried out in a fractionating column 400*C at bottom 40*C at top

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aluminium characteristics

High strength to weight ratio
Good conductor of heat and electricity
Non-toxic
Resists corrosion

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Uses of aluminium

Aeroplane bodies
Overhead power cables
Saucepans
Food cans
Window frames

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Iron characteristics

Strong
Withstands collisions

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Uses of iron

Car bodies
Iron nails
Ships
Bridges

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Extraction of iron

Raw materials- iron ore, coke, limestone, air (mixed added at top)

Oxygen + coke ---> carbon dioxide

Carbon dioxide + coke ---> carbon monoxide

Carbon monoxide reduces iron (iii) oxide in iron ore

Iron melts, collects at bottom, tapped off

Calcium carbonate in limestone decomposes ---> calcium oxide

Calcium oxide + silicon dioxide (impurity) ---> calcium silicate

Calcium silicate melts, collects as molten slag, tapped off

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Electrolysis of aluminium

Aluminium melts and collects at the bottom,tapped off

Some oxygen produced at positive electrode
Reacts with the graphite ----> carbon dioxide gas

Positive electrode must be replaced after burning away

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Extraction of aluminium electrodes

Graphite (carbon)

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Extraction of aluminium Electrolyte

Solution of aluminuim oxide dissolved in molten cryolite

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Main ore of aluminium

Bauxite -> must first be purified before producing aluminium oxide

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Aluminium oxide

High melting point
Must be dissolved in molten cryolite

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Ore

Rocks with enough metal worth mining for

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Unreactive metals in ores

Occur as elements

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Ractive metals in ores

Found as compounds from which they must be extracted

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Reactive metals

Electrolysis of the molten chloride/oxide

Most powerful method but very expensive

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Medium/ lower reactivity metals

Heat with a reducing agent (carbon/carbon monoxide)

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Gold/ silver -unreative

Occur naturally as the elements