C1.3 Metals and Their Uses Flashcards
Extracting metal from ores is economical because
Ores contain lots of metal
Most metals are found as
Compounds, and require chemical reactions to extract the metal
Which metals are found in the earth as themselves and not in a compounds
Unreactive metals such as Gold.
How are metals less reactive than carbon extracted from their oxides
By reduction with carbon e.g Iron oxide is reduced in a blast furnace to produce iron (the oxygen reacts with the carbon to form carbon dioxide)
Ores are often
Oxides of the metal e.g the aluminium ore is bauxite (aluminium oxide Al2O3)
Metals more reactive than carbon are extracted form their oxides through
Electrolysis of molten compounds
Why are metals more reactive than carbon expensive?
The large amounts of energy needed to separate them from their oxides through electrolysis is very expensive
How can copper be removed from its ore?
Smelting (the heating of the ore in a furnace)
How is copper purified?
Through electrolysis
Why is copper purified?
Impure copper doesn’t conduct electricity well, this is not useful as copper is used to make electrical wiring. Pure copper is a much better conductor
What is Electrolysis
The breaking down of a substance using electricity
What is required in electrolysis
A liquid to conduct the electricity (electrolyte.) These are often metal salt solutions. Electrolytes have free electrons which conduct electricity
What happens at the anode?
Electrons are taken away/lost causing them to become atoms or molecules
What happens at the cathode?
Electrons are given/gained causing them to become atoms or molecules
Electrolysis of copper:
The cathode is made of a thin piece of pure copper whilst the anode is made up of an lump of impure copper. Electrons are lost at the anode causing them to go into the copper sulfate solution. Cu2+ ions gain electrons at the cathode and turn into copper atoms. The impurities are left at the anode as sludge whilst the pure copper atoms bond to the cathode
How else can copper be extracted?
Phytomining or Bioleaching
What is Phytomining?
When plants absorb metal compounds and are then burned to produce ash which contains metal compounds
What is Bioleaching?
The use of bacteria to produce leachate solutions which contain metal compounds. Bacteria get energy from the bond between copper and sulfate and separate the two in the process. The leachate (solution produced by the process) contains copper and can be filtered to extract copper.
Copper can also be extracted through ___________ with iron
Displacement
In electrolysis positive ions move towards the
Negative electrode
Why is the extraction of Aluminium and Titanium so expensive?
Because they cannot be extracted by reduction with carbon and there are lots of stages in the process meaning large amounts of energy are required
Why should we recycle metals?
Extracting them requires limited resources and is expensive due to energy needed and effects on the environment. Theres is a limited amount of metal on the earth, recycling conserves this. Recycling reduces landfill and therefore pollution
Impure iron is
Brittle
Iron from a blast furnace is
96% Iron
