Extracting Metals Flashcards
What is an ore?
A metal ore is a rock which contains enough metal to make it worthwhile extracting the metal from it
What is the ore in many cases?
The oxide of the metal
How do most ores need to be extracted?
Using chemical reactions
How can economics affect metal extraction?
If the market price of a metal drops a lot it might not be worth extracting it
As technology improves it becomes possible to extract more metal making it worth it
What two ways can a metal be extracted from its ore chemically?
Reduction
Electrolysis
If an ore is concentrated, what does that mean?
The unwanted Rocky material is removed
What else can electrolysis to used to do?
Purify the extracted metal
What does reduction mean?
Using carbon- The removal of oxygen
Often requires electrolysis after to purify the metal
What determines whether a metal can be extracted by reduction?
It’s position in the reactivity series
Which metals can / can’t be extracted by reduction?
Metals below carbon can
Metals above carbon can’t
This is because carbon can only take the oxygen away from metals which are less reactive than itself
How are metals more reactive than carbon extracted?
Extracted using Electrolysis of molten compounds
Why is electrolysis much more expensive than reduction?
It used a lot more energy due to the high temperature used to melt the oxide so it can be extracted
How is copper extracted?
Copper can be extracted by reduction with carbon
The ore is then heated in a furnace (smelting)
The copper produced is impure and doesn’t conduct electricity very well
Electrolysis is used to purify it
Define electrolysis?
The breaking down of a substance using electricity
What is the liquid required to conduct the electricity in electrolysis known as?
The electrolyte
What are the electrolytes often?
Metal salt solutions made from the ore
Or molten metal oxides
What does the electrolyte have allowing the process to work?
Free ions
Where are electrons taken from / given too?
Taken away by the positive anode and given away by the negative cathode, as ions gain or lose electrons they become atoms or molecules and are released
Describe how electrolysis is used to get copper?
1) electrons are pulled off copper the atoms at the anode cashing them to go into solution as Cu2+ ions
2) Cu2+ ions near the cathode gain electrons and turn back into copper atoms
3) the impurities are dropped at the anode as a sludge whilst pure copper atoms bond at the cathode
Why do more reactive metals react more vigorously than less reactive metals?
If you put a reactive metal into a solution of a dissolved metal compound the reactive metal will replace the less reactive metal in the compound (displacement)
Why does displacement happen?
The more reactive metal bonds more strongly to the non metal part of the compound (pushes out the less reactive metal)
Why is it useful that scrap iron can be used to displace copper and what’s the equation for this?
Iron is much cheaper than copper
Copper sulfate + iron —> Iron sulfate + copper
Why Is it important to recycle as much copper as possible?
The supply of copper rich ores is limited and the demand for copper is growing which may lead to shortages in the future
What are two ways of extracting copper from low grade ores or from the waste of copper extraction?
Bioleaching
Phytomining
