Metals and their uses Flashcards
Define an ore.
A rock which has enough of a metal or a metal compound in it to make it economical to extract the metal
How are unreactive metals such as gold found and extracted?
How are most metals found and extracted?
Found in the Earth in its pure form, so can be separated from rocks by physical methods.
Most metals are found as compounds which need chemical reactions to extract the metal.
How are metals less reactive than carbon extracted from their oxides?
What type of reaction takes place and what happens in the reaction?
Metals less reactive than carbon can be extracted from their oxides by heating them with carbon, a reduction reaction takes place as carbon removes the oxygen from the oxide to produce the metal.
How are metals more reactive than carbon such as aluminium extracted?
Give two reasons why is this not ideal.
Aluminium has to be extracted by electrolysis of molten aluminium oxide.
1) Electrolysis uses large amounts of energy and the processes consist of many stages, which makes it very expensive.
2) As a result the metals themselves are expensive to buy.
How is copper extracted from copper-rich ores and how is it purified?
What are the problems with these processes?
Why do we need to be able to extract copper from low-grade ores?
The ores are heated strongly in a furnace (smelting), then purified by electrolysis.
Traditional mining and extraction methods such as smelting and electrolysis have major environmental impacts.
Copper-rich ores are a limited resource.
Describe the process of phytomining.
Uses plants to absorb copper compounds from the ground, then the plants are burnt to produce ash from which copper can be extracted.
Describe the process of bioleaching.
Give two ways in which copper can be obtained from solutions of copper compunds.
Uses bacteria to produce solutions containing copper compounds.
1) Solutions of copper compounds can be reacted with metals more reactive than copper, such as scrap iron, to displace the copper.
2) Copper can also be extracted from solutions of copper compounds by electrolysis.
Give three reasons why we should recycle metals.
1) Extracting them uses limited resources.
2) Saves energy needed to extract metal.
3) Less fossil fuel is needed to provide the energy for the metal to be extracted.
Define an alloy.
A metal made up of a mixture of metals and/or carbon.
How is most iron we produce used?
It is used to make steel alloys by mixing it with carbon, and other elements.
How does the quantity of carbon in steel affect its properties?
Low-carbon steels are easily shaped, whereas high-carbon steels are hard.
What is a stainless steel?
An alloy of iron, containing larger amounts of other metals to make it resistant to corrosion.
Why are pure copper, gold, iron and aluminium not very useful? How are they made useful? What is gold alloy used for? What is aluminium alloy used for? Name two alloys of copper.
They are too soft for many uses.
They are mixed with small amounts of similar metals to harden them, ready for everyday use.
Gold alloy - jewellery
Aluminium alloy - aircrafts and buildings
Copper alloys - bronze and brass.
What are the elements in the central block of the periodic table called?
What properties do they share?
Transition metals
1) Like other metals, they are good conductors of heat and electricity.
2) They are malleable, so can be bent or hammered into shape.
3) They are ductile.
Give three properties of copper that make it useful for electrical wiring and plumbing.
1) It is a good conductor of heat and electricity.
2) It can be bent but it is hard enough to keep its shape and be used for pipes or tanks in water and heating systems.
3) It does not react with water
