Extracting Metals Flashcards
Why can metals below carbon in the reactivity series be reduced by carbon?
Because carbon only can take the oxygen away from metals that are less reactive than itself.
How must metals more reactive than carbon be extracted?
Electrolysis of molten compounds
Why is electrolysis of molten compounds expensive?
> because it requires vast amounts of energy to melt the ionic compounds.
Why is impure reduced copper not very useful?
Because it is impure it is not a good conductor of electricity- one of main uses of Cu
How can pure copper be obtained?
> copper ores are reduced in a blast furnace with carbon - smelted
> molten reduced copper is electrolysed
> very pure copper is made
What is electrolysis?
The breaking down of a substance using electricity
What is an electrolyte?
> a liquid that conducts the electricity in electrolysis
What happens at the anode?
> oxidation , electrons are taken away
What happens at the cathode?
> electrons are gained by the ( given away from
What happens in the electrolysis of copper?
> electrons are pulled off copper atoms at the anode, causing them to go into the solution as Cu2+ ions
> the Cu2+ ions near the cathode gain electrons and turn back into pure
Cu atoms, bonding to the cathode.
> the impurities are dropped at the anode as sludge,
A more reactive metal will…
Displace a less reactive one in an aqueous of its compound.
Why can a more reactive metal displace a less reactive one?
> the more reactive metal will bond more strongly and react more vigorously than the less reactive one.
What are two methods of obtaining copper from low grade copper ore?
> what are their adv. and disadv. over traditional methods?
> bioleaching
> phytomining
> less of an impact on environment and more sustainable use of ores
> slower
How does bioleaching work?
> a bacteria is used to separate the copper from copper sulfide
> bacteria gains energy from the bond between copper and sulphur, separating out the copper in the process
> the solution produced by the process (leachate) can be filtered to obtain the copper
What is a leachate?
> solution produced by the bioleaching process
How does phytomining work?
> plants are grown in soil contains copper
> plants cannot use the copper so it gradually builds up in the leaves
> plants can be harvested, dried and burned in a furnace and the copper collected from the ash left in the furnace by displacement with iron
What are the advantages of mining for ores?
> provides us with use products
> brings jobs and stimulates local economy
- better transport and health
What are the disadvantages of metal ore mining?
> creates noise +pollution
> scarring of landscape
> loss of habitat
> dangerous mine shafts
What are the advantages of recycling metals?
> only takes a fraction of the energy needed to mine and extract metal from ores
- less fossil fuels burned
- less global dimming and climate change
reduces waste to landfills
> conserves finite amount of ores
What is an ore?
> a rock containing enough of the desired metal to make extracting the metal worthwhile
Why is scrap iron used to extract copper?
> because it is inexpensive
> it displaces it as is more reactive
