C6 - Electrolysis
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Define ‘Electrolysis’
Breaking down using energy.
When can ionic substances be electrolysed? - Why?
• When the are molten or dissolved. - Because only then are the ions free to move and carry charges.
Where do positively charged ions go?
Cathode.
Where do negative ions go?
Anode.
D. Substance broken down by electrolysis?
Electrolyte.
Electrolysis can only be used to break down an ………. compound.
Ionic.
What happens when electrolysis happens in an aqueous solution?
The least reactive element is produced at the cathode.
What happens at the anode?
Negative electrons loose their electrons, oxidation.
How is Aluminium extracted from its ore?
Electrolysis.
What is the Aluminium mixed with to lower its melting point?
Cryolite.
What ions do metals form?
Posative.
What is Aluminium oxide extracted from?
Bauxite.
Why do the carbon anodes have to be replaced regularly?
Because they gradually burn away as they react with oxygen to form carbon dioxide gas.
Three products made when you electrolysis sodium chloride solution (brine) ?
Chlorine gas, Hydrogen gas, Sodium hydroxide solution
Equation for chemical reaction at the anode of a hydrogen fuel cell?
2H^2 ~ 4H+ + 4e-
Equation for chemical reaction at the cathode of a hydrogen fuel cell?
O^2 + 4H+ + 4e- ~ 2H^2O
Overall equation for the chemical reaction in a hydrogen fuel cell.
2H2 + O2 ~ 2H2O
Why must the electrodes be inert?
So that they don’t react with the products