Edexcel IGCSE Chemistry - Extraction of Metals

why are most metals not found pure in Earth’s crust?

they have reacted with other elements

why are some metals found as uncombined elements in Earth’s crust?

they are unreactive

what is a metal-containing compound in the earth’s crust called?

a metal ore

what happens as a metal becomes more reactive (in terms of ores)?

it becomes harder to extract it from its compound

how can metals be extracted from ores?

reduction reactions

what is the most common reducing agent in a metal ore reduction reaction?

carbon - heated with carbon monoxide

what metals can be extracted from their ores by reduction with carbon?

ones that are less reactive than carbon as carbon can displace them

where is carbon in the reactivity series?

between aluminium and zinc

how are metals more reactive than carbon extracted from their ores?

electrolysis as carbon will not be able to displace them from their compounds

what are the common properties of iron, copper and aluminium?

• dense and shiny

• have high melting points

• have high tensile strength - strong and hard to break

• are malleable

• good conductors of heat and electricity

what is the main problem with iron?

it corrodes easily

what is iron used for?

wrought iron (almost pure iron) is used for gates and railings

what properties are specific to aluminium?

• reacts very quickly with oxygen in the air to form aluminium oxide - makes it unreactive with surroundings - does not corrode easily

• much less dense than iron

what are the uses of aluminium?

• products that come into contact with water like drinks cans - doesn’t corrode easily

• bicycle frames and aeroplanes - light, not dense

what properties are (sort of) specific to copper?

very good conductor of heat and electricity

what are the uses of copper?

• electrical components and wiring - has low resistance

• heating systems

what is the main component of steel?

iron

what are the 3 types of steel?

• low carbon (0.1-0.3% carbon)

• high carbon (0.22-2.5% carbon)

• stainless steel (chromium and maybe nickel added)

what are the properties of low carbon steel?

easily shaped

what are the uses of low carbon steel?

car bodies

what are the properties of high carbon steel?

very strong, inflexible, brittle

what are the uses of high carbon steel?

bridges

what are the properties of stainless steel?

corrosion-resistant, hard

what are the uses of stainless steel?

cutlery

what are alloys?

mixtures of metals and other elements

why are alloys harder than pure metals?

• the ions of the different elements are different sizes

• this means that the layers cannot slide over each other easily so they are hard