Obtaining and using metals Flashcards
How are metals found
Some unreactive ones are found uncombined such as gold
Most metals are found in ores but there’s s limited amount so they’re finite resources
How is a metal ore formed
Oxidation
The gain of oxygen
2mg + o -> 2MgO
How is a metal extracted from its ore
Reduction
Loss of oxygen
2CuO + C -> 2Cu + CO2
What is the reactivity series
Potassium Sodium Calcium Magnesium Aluminium CARBON Zinc iron tin lead
How are metals more reactive than carbon extracted
By electrolysis
How are metals less reactive than carbon extracted from their ore
By heating them with carbon in a displacement reaction
Iron(III) oxide + carbon
Iron + carbon dioxide
What is the formula for iron (III) oxide
2Fe2O3
How is electrolysis used to remove aluminium from its core
Al2O3 is found in bauxite
It is melted and used as the electrolyte
Aluminium and oxygen atoms are formed the Aluminium sinks to the bottom of the tank as molten aluminium metal
What are the properties of metals
They’re strong but can be bent or hammered into different shapes so are good for car bodies and bridges
Good conductors of heat so good for sauce pans and electricity so good for electrical wires
What are the properties of aluminium
Low density
Resistant to corrosion
Not that strong but forms strong alloys
Used for window frames electricity cables and aircraft
What are the properties of copper
Hard
Strong
High melting point
Good conductor of electricity
Doesn’t react with water so can be used for water pipes
Used in electrical wires
What are the properties of gold
Shiny
Very easy to shape
Unreactive
Used in jewellery tooth filling and electrical circuits
What is corrosion
Some metals corrode over time when they become oxidised
Metals high in the reactivity series are more likely to corrode because they react more easily with water
What is rust
When iron corrodes it combines with water and oxygen and forms hydrated iron(III) oxide
Iron + oxygen + water -> hydrated iron (III) oxide
Why is pure iron not good
When iron is extracted it is impure and brittle so can be used for ornamental railings but has not other uses
When the impurities are removed the pure iron has atoms arranged in layers that DNA easily slide over each other so it is soft and too bendy for most uses
What is an alloy
A mixture of two or more metals or a mixture of a metal and a non metal
Why are alloys better
The different sized particles disrupt the layers so it’s much harder for the layers to slide over each other making it less bendy
What are gold alloys used for
To make jewellery
The proportion of pure gold is in carats
Pure gold is 24 carat
What are smart alloys
They have shape memory so remember their original shape
Eg nitinol is a mixture of nickel and titanium
If you bend this wire it will go back to its original shape when heated
They’re used in glasses frames and in stents used to keep blood vessels open
Why is it important to recycle metals
It uses less resources because there’s s limited amount of metal in the earth
It uses less energy because extracting metals takes up lots of energy that comes from burning fossil fuels
It is much cheaper
It creates much less rubbish and reduces the amount that goes to landfill and pollutes the surrounding
What are the benefits of recycling
Every one kg of aluminium cans recycled saves
95% of the energy
4kg of aluminium ore
Lots of waste
What is a hydrocarbon
A chemical made of hydrogen and carbon only
What is a crude oil
A mixture of different sized hydrocarbon molecules
What happens in fractional distillation
Heated crude oil is piped in at the bottom and the vaporised oil rises up and condenses at different layers
Describe bitumen
Comes from the bottom of the fractional distillation column
40 carbon atoms
Used to surface roads and roofs
Describe fuel oils
Condenses at 340c second in the distillation column
Used as fuel for ships and in some power stations
35 carbon atoms
Describe diesel
Condenses at 250c third in the column
20 carbon atoms
Used as fuel for lorries trains and some cars
Describe kerosene
Condenses at 180c and fourth in the column
15 carbon atoms
Used as aircraft fuel
Describe naphtha
Condenses at 110c fifth in the column
10 carbon atoms
Used as lighter fluid and in the chemical industry
Describe petrol
Condenses at 40c fifth in the column
8 carbon atoms
Used as fuel for cars
Describe gases
Top of the column
3 carbon atoms
Used for cooking and heating
