Electrolysis Revision mat
- Created by: Joe12345678
- Created on: 14-10-15 18:11
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- C3 - Electrolysis
- Electrolytes
- It is the thing being sperated
- They are ionic substances in the molten state or dissolved in water
- Ions
- Positively charged cations migrate to the negatively charged cathode
- Negatively charged anions go to the positively charged anode
- OILRIG
- Oxidation Is Loss of electrons
- Occurs at the anode
- Reduction Is Gain of electrons
- Occurs at the cathode
- Oxidation Is Loss of electrons
- Sodium manufacture
- Created by the electrolysis of molten sodium chloride
- Sodium is produced at the negative cathode
- Sodium can be used in street lamps and as a coolant in some nuclear reactors
- Chlorine is produced at the positive anode
- Half Equations:
- Cathode: Na+ + e- --> Na
- The ions are reduced to become sodium atoms
- Anode: 2Cl- --> Cl2 + 2e-
- The ions are oxidised and pair up to form chlorine molecules
- Cathode: Na+ + e- --> Na
- Molten lead bromide is electrolysed in the same way - except molten lead bromide is the electrolyte
- Cathode = lead (liquid)
- Anode = bromine (gas)
- Electrolysis of aqueas solutions
- Molten ionic salts only contain the ions of the salt
- But dissolve the salt in water and there are H+ and OH- ions from the water aswell. This can make things more interesting.....
- At the anode the simplest ion is discharged... e.g. Cl- is discharged not OH-
- At the cathode a metal will be discharged if it's less reactive than hydrogen.
- If it is more reactive hydrogen is discharged... e.g. Copper is less reactive than hydrogen so it will be discharged at the cathode during electrolysis of aqueous copper salts
- Molten ionic salts only contain the ions of the salt
- Formation of products in electrolysis using inert electrodes
- Inert electrodes are made of unreactive material so they don't take part in the reaction
- Copper chloride solution , CuCl2
- Cathode = Copper (s)
- Anode = Chlorine (g)
- Copper sulfate solution, CuSO4
- Cathode = copper (s)
- Anode = Oxygen (g)
- Sodium sulfate solution, Na2SO4
- Cathode = Hydrogen
- Anode = Oxygen
- Sodium chloride solution, NaCl
- Cathode = Hydrogen (g)
- Anode = chlorine (g)
- Making pure copper
- The mass of the anode decreases during the electrolysis
- The mass of the cathode increases as the pure copper is attracted to it
- The anode is made of impure copper and the pure copper is attracted to the cathode where pure copper is then created
- Any impurities form as sludge under the anode
- Electroplating
- This can be used for 2 reasons
- It can Improve the appearance of something
- It can protect a metal object and make it more resistant to corrosion
- This can be used for 2 reasons
- Electrolytes
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