Getting Metals From Rocks Flashcards
How does the profitability of metal extraction change over time?
If the selling price of a metal drops a lot, the natal night no longer be worth extracting. If the selling price of a metal increases a lot then it might be worth extracting. As technology improves, it might be worth extracting a metal that it wasn’t worth extracting in the past.
What is a metal ore?
A metal ore is a rock the contains enough metal compound to make it worth extracting.
What is a reduction reaction? What happens?
A metal can be extracted from its ore chemically by reduction using carbon. When an ore is reduced oxygen is removed from it.
E.g.
2Fe2 + 3C –> 4Fe + 3CO2
Why is the reactivity series important when looking at extraction?
If the metals that you want to extract are above carbon in the reactivity series, carbon will not be able to reduce it. This means that it must be extracted using electrolysis. If the metals are below carbon, carbon will be able to reduce it and so the metals can be extracted by reacting with carbon.
Why can reacting a metal with carbon only work if the metal is below it in the reactivity series?
Because carbon can only take the oxygen away from metals which are less reactive than carbon itself.
Why is it more expensive to extract a metal using electrolysis than it is to react it with carbon?
A high temperature is needed to melt aluminium oxide so that aluminium can be extracted. This requires a lot of energy which makes it expensive.
Why is copper purified by electrolysis despite being extracted by reaction with carbon?
Copper can be easily extracted by reduction with carbon. The ore is heated in a furnace which is called smelting. However, the copper produced this way is impure and impure copper doesn’t conduct electricity very well. This isn’t very useful. Electrolysis can purify the copper even though it is quite expensive. This produces very pure copper which is a better conductor.
What is electrolysis?
Electrolysis is the breaking down of a substance using electricity. It requires a liquid to conduct the electricity called the electrolyte.
How does the process of electrolysis work?
The electrolytes are often metal salt solutions made from the ore (e.g. copper sulfate) or molten metal oxides. The electrolyte has free ions- these conduct the electricity. Electrons are taken away by the positive anode and given away by the negative cathode.
What is a displacement reaction an how does it work?
More reactive metals react more vigorously than less reactive metals. If you put a reactive metal in a solution of dissolved metal compound, the reactive metal will replace the less reactive metal in the compound. This is because the more reactive metal bonds more strongly to the non-metal bit of the compound and pushes out the less reactive metal.
Copper rich ores are in short supply. Describe two ways that you can get low grade ores from the ground.
Bioleaching uses bacteria to separate copper from copper sulfide. The bacteria get energy from the bond between copper and sulfur separating out the copper from the ore in the process. The leachate (the solution produced by the process) contains copper which can be extracted. Phytomining involves growing plants in soil that contains copper. The plants have no way of getting rid of the copper so it gradually builds up. The plants then get collected, dried and burned. The copper can be collected from the ash.
Give a balanced argument regarding metal extraction.
Mining ores is good because it means that useful products can be made. It provides people with jobs and brings money in to the area. On the others hand mining ores is bad for the environment because it causes noise and scars the landscape. Habitats can be destroyed and if the mines are left for a long period of time, can become dangerous.
Why should we recycle metals? Give three reasons.
Mining and extracting metals uses a lot of energy so by recycling you can cut down on the amount of energy needed. Metals are finite resources so by recycling we conserve them. We reduce the amount of CO2 emissions by cutting down on burning fossil fuels.
What are the three basic properties of all metals?
They are strong but they are malleable as they can be shaped. They are very good at conducting electricity and they can also conduct heat
What is an alloy?
When at least one metal and another element mix together. This creates an alloy with the properties they want.
