Electrolytic P rocesses What is electrolysis Breaking down an ionic substance using electricity Metals have a positive charge and non metals have a negative charge Hydrogen is an exception it is a non metal with a positive charge ID: 576552
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Slide1
Topic 3 revision: Electrolytic ProcessesSlide2
What is electrolysis?Breaking down an ionic substance using electricity.Metals have a positive charge and non metals have a negative charge.
Hydrogen is an exception (it is a non metal with a positive charge.Slide3
Anode
Cathode
= bromide ion
= lead ionSlide4
What happens at the electrodes?Use the electrolysis of lead bromide as an example.
The ions discharge and elements re-form.
So, at the anode bromine forms and at the cathode lead forms. Slide5
Ionic half equationsElectrolysis of CuCl2
Anode: 2Cl
-
Cl
2
+ 2e
-Cathode: Cu
2+ + 2e- Cu
Electrolyse these:
CaF2AlBr
3Slide6
Electrolyus
2H
+
+ 2e
-
H
2
2Cl
-
Cl
2 + 2e
-
Na
+
and OH-
are
left behind to create NaOH in the solution.
Only the least reactive element will form at the electrode.Slide7
anode
At the anode
anode
Cu
Cu
e
-
e
-
e
-
e
-
Cu
Cu
2+
+ 2e
-
Cu
2+
Cu
2+Slide8
cathode
cathode
At the cathode
cathode
Cu
Cu
e
-
e
-
e
-
e
-
Cu
2+
+ 2e
-
Cu
Cu
2+
Cu
2+
Pure
CopperSlide9
anode
What about the impurities
anode
Au
Pt
Ag
As the anode dissolves
The impurities are released
They sink to the bottom
As anode slime
Valuable stuff
Anode
SlimeSlide10
Refining copper
At the negative cathode
Positive copper ions drift to the cathode.
They gain electrons and become copper atoms
Cu
2+
+ 2e-
Cu
The cathode is electroplated
At the positive anode
Copper atoms lose electrons and become copper ions.
The positive ions drift away from the anodeCu
Cu
2+ + 2e
-The anode dissolvesSlide11
ElectroplatingTwo uses:
To galvanise metals (to stop corrosion)
To make things more attractive.