Extraction and use of metals Flashcards
the more reactive a metal is…
the harder it is to extract it from a compound
lots of common metals react with…to form…
oxygen…oxides
what is the reaction that involves the separation of a metal from the oxygen?
a reduction reaction
what is the reducing agent?
the substance that reduces the metal
what is the most common reducing agent?
carbon
copper oxide is reduced to copper:
2CuO + C = 2Cu + CO2
Methods of extraction are linked to the…
order of reactivity
only metals…than…can be reduced by…
less reactive…carbon…carbon
very reactive metals form…
very stable ores
metals that are more reactive than carbon need to be extracted using…
electrolysis
what is the melting point of aluminium?
2000 degrees celcius
what is aluminium dissolved in?
molten cryolite (a less common ore than aluminium)
What does the molten cryolite do?
it brings the temperature down to about 900 degrees celcius
what electrode are the aluminium ions attracted to?
the negative
what happens to the aluminium atoms once they gain electrons?
they sink to the bottom
why do the positive electrodes always need to be replaced?
they get worn down by reacting with oxygen
at the negative electrode:
Al3+ + 3e- –> Al
at the positive electrode:
202- –> O2 + 4e-
why is electrolysis expensive?
- it uses lots of electricity
- the need to heat the electrolyte
- the frequent replacement of electrodes
what are the raw materials used for extracting iron from iron ore?
- iron ore
- coke
- limestone
what is coke?
almost pure carbon
what is the purpose of limestone?
to take away impurities in the form of slag