How do we have to extract metals that are more reactive than carbon?
Using electrolysis of molten compounds
Give an example of a metal that has to be extracted using electrolysis
Name a disadvantage of using electrolysis compared to reduction using carbon?
Describe how extracting aluminium is an expensive process
A high temperature is needed to melt aluminium oxide so that aluminium can be extracted - requiring a lot of energy
Why do we use electrolysis with copper when we can extract it using reduction with carbon?
After extracting the copper through reduction with carbon it is still very impure
- electrolysis is used to purify it
Describe how copper is purified using reduction with carbon, and name the process
Copper ore is heated in a furnace
What is the problem with impure copper?
It can't conduct electricity very well, which is a problem as a lot of copper is used to make electrical wiring
Why do we extract copper using reduction with carbon BEFORE we electrolyise it?
It's less expensive than just using electrolysis
Breaking down a substance using electricity
What does electrolysis require?
A liquid to conduct the electricity, known as the electrolyte
What 2 things are electrolytes usually made of?
1. Metal salt solutions made from the ore (e.g. copper sulphate
2. Molten metal oxides
How can electrolytes conduct electricity?
Because they contain free ions
Describe what the negative and positive electrodes do with the electrons
Negative electrode - gives away electrons
Positive electrode - takes away electrons
As the ions lose or gain electrons, what happens to them?
They become atoms or molecules and are released
Give the 4 steps of how electrolysis is used to get pure copper
1. Electrons are pulled off copper atoms at the positive electrode
2. This causes them to be released into the solution as Cu2+ ions
3. Cu2+ ions near the negative electrode gain electrons and turn back into copper atoms
4. The impurities are dropped at the positive electrode as sludge, whilst the pure copper atoms bond to the negative electrode
Describe the negative electrode for the electrolysis of copper
Starts off as a thin piece of pure copper and more pure copper adds to it
Describe the positive electrode for the electrolysis of copper
A lump of impure copper which will dissolve
Why is the Statue of Liberty green?
Because the copper coating reacts with the oxygen in the air to form copper carbonate
More reactive metals react ____ ____ than less reactive ones
More reactive metals react more vigorously than less reactive ones
What happens if you put a reactive metal into a soltion of a dissolved metal compound?
The reactive metal will replace the less reactive metal in the compound
Why do more reactive metals displace less reactive metals?
The more reactive metal bonds more strongly to the non-metal part of the compound and pushes out the less reactive metal
Explain what happens when you add scrap iron to a solution of copper sulfate, and why this is useful
The more reactive iron displaces the copper, so you are left with copper metal and iron sulfate
This is useful because iron is cheap but copper is expensive
What happens if a piece of silver is put into a copper sulfate solution?
Because the copper is the more reactive metal, and it is already bonded to the sulfur
Why is it important to recycle as much copper as possible?
Because the supply of copper-rich ores is limited
The demand for copper is ____, and this may lead to ____ in the future
The demand for copper is growing, and this may lead to shortages in the future
What is the demand and limited supply of copper causing scientists to do?
Look into new ways of extracting copper from low-grade ores, or from the waste that is currently produced when copper is extracted
Name two examples of new methods to extract copper
Using bacteria to separate copper from copper sulfide.
Describe the process of bioleaching
The bacteria get energy from the bond between copper and sulfur, serparating out the copper from the ore in the process. The leachate (the solution produced by the process) contains copper, which can be extracted
Give an example of how the copper can be separated out from the leachate
Growing plants in soil that contains copper, then harvesting them
Describe the process of phytomining
1. Plants are grown in soil that contains copper.
2. The plants can't use or get rid of the copper so it gradually builds up in the leaves.
3. The plants can be harvested, dried, and burned in a furnace.
4. The copper can be collected from the ash left in the furnace.
Name an advantage of bioleaching and phytomining to traditional methods of copper extraction
They have a much smaller impact on the environment
Name a disadvantage of bioleaching and phytomining to traditional methods of copper extraction
They are much slower