Topic 4 - Flashcards
An electrolysis cell has two electrodes. What is the name of the positive electrode?
Anode
What is the liquid called in an electrolysis reactions?
Electrolyte
In electrolysis, which direction do the electrons travel?
Anode ➔ Cathode
Which ions are attracted to the negative electrode (cathode) during electrolysis?
Positive ions (opposite charges attract)
The electrodes in an electrolysis cell are normally made of inert carbon. What does the term ‘inert’ mean?
It is unreactive, so will not take place in the reaction.
In electrolysis, is the ion that gains electrons oxidised or reduced?
Reduced
In the electrolysis of molten lead bromide, what is the product at the anode?
Bromine
In terms of electrons, what does oxidation mean?
Loss of electrons
In electrolysis, why does the compound you’re trying to separate need to be molten or dissolved?
So that the ions are free to move around (and go to their respective electrode)
In electrolysis, which electrode would chloride ions (Cl-) be attracted to?
Anode
Which two of the following chemical processes are used to extract metals from their ores?
Electrolysis
Reduction with carbon
How is a metal extracted from a metal compound using electrolysis?
A compound is split into its elements using electricity
Why is electrolysis not used to extract all metals?
Electrolysis is expensive because it requires a large amount of electricity
When should a metal be extracted by carbon reduction?
When the metal is less reactive than carbon
Why is electrolysis used to extract aluminium from its ores?
It is more reactive than carbon
What is the name of the substance that is mixed with aluminium oxide to lower its melting point?
Cryolite
In the electrolysis of a solution, which two ions are present from the water molecules themselves?
H+
OH-
In the electrolysis of aqueous solutions, what is the rule for determining which ion will be oxidised (lose electrons) at the anode (positive electrode)?
It will always be the OH-, unless there is a halide ion (such as Cl-, or Br-) present
In the electrolysis of aqueous solutions, what is the rule for determining which ion will be reduced (gain electrons) at the cathode (negative electrode)?
It will always be the H+ ion, unless Cu2+ is present (another way of phrasing it would be that it is always the ion of the least reactive element)
