Most Difficult Topics
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Which ions do anodes attract?
Anions
Which ions do cathodes attract?
Cations
What is the electrolyte in electrolysis
The substance that the electrolysis is done on
Define the term reduction
When a substance gains electrons
Define the term oxidation
When a substance loses electrons
Which reaction happens at the anode?
Oxidation
Which reaction happens at the cathode?
Reduction
What is the overall reaction for the extraction of iron?
2Fe2O3 + 3C -> 3CO2 + 4Fe
What happens when C reacts with O2
It increases the temperature to 2000C and forms CO2
CO2 + C ->
2CO
3CO + Fe2O3 ->
2Fe + 3CO2
What is the main impurity of hematite
SiO2 (sand)
Which chemical is used to remove SiO2 from iron?
CaCO3 (limestone)
What is the first step to remove sand?
CaCO3 -> CaO + CO2
CaO + SiO2 ->
CaSiO3
How is CaSiO3 removed from iron?
The molten iron sinks to the bottom due to being more dense than CaSiO3, so the Fe can be removed with a tap.
What is CaSiO3 used for?
Road surfacing
Why can Al not be extracted by carbon reduction (displacement)?
It is more reactive than carbon
Which material are the electrodes made of in the electrolysis of Aluminium
Graphite
What is produced at the anode in electrolysis of Aluminium?
Oxygen
What is produced at the cathode in electrolysis of Aluminium?
Aluminium
Why do anodes need to be replaced over time?
At the hot temperature required to melt Al, oxygen reacts with graphite, making CO2, and eroding the anode.
What is one use of aluminium?
Making Planes
What do the electrodes look like in the industrial electrolysis of aluminium?
Anodes are attached to the same cell, many of them at the same time. The cathode is the chamber itself.