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
Most iron is converted into
Steel
What is steel?
An alloy of iron and carbon
Properties of low-carbon steels and their uses
Easily shaped. Used for the making of car bodies
Properties of high-carbon steels and their uses
Very hard, inflexible. Used to make blades for cutting tools and to construct bridges
Properties of stainless steel and its uses
Corrosion resistant. Used for cutlery, containers for corrosive substances.
What does stainless Steel contain?
Iron, Carbon, Chromium and sometimes Nickel
Impure iron is used as
Cast iron
Pure iron is
Too soft, bendy and easily shaped due to the layers of atoms being able to slide over each other
Different elements have
Different sized atoms
Why are alloys harder than pure metals?
When adding a different element to an pure metal, the regular layers of atoms will be disturbed due to the different sized atoms of the other element added. This means they cannot slide over each other, making them harder
Many metals used today are
Alloys
What is Bronze made up of?
Copper and tin. It is harder than pure copper and is good for making medals and statues
What is cupronickel made up of?
Copper and Nickel. It is hard and does not corrode. It is used to make silver coins
What are Gold alloys used to make?
Jewellery. Pure Gold is too soft, metals such as zinc, copper, silver and nickel are used to harden the Gold
What are Aluminium alloys used to make?
Aircraft. Pure aluminium has a low density, but it is alloyed with small amounts of other metals to make it stronger
Elements in the central block of the Periodic table are known as
Transition metals
Transition metals are
Good conductors of heat and electricity and can be bent into shape
What are transition metals useful for?
Structural materials and for making things that must allow heat and electricity to pass through them easily
Copper is useful for
Electrical wiring and plumbing
What are the properties of copper?
Good conductor of heat and electricity, can be bent, does not react with water
How are some metals protected from corroding?
By painting the metal
What is ‘metal fatigue’?
When metals have strains and stresses put on them over time, this leads to them breaking
