Electrolysis and Salts - Revision Notes

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  • Created on: 22-06-11 09:45
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Electrolysis of Brine
Brine is merely sodium chloride (NaCl) dissolved in water.
If you perform electrolysis on brine you will get three substances: chlorine,
hydrogen and sodium hydroxide.
The cations move towards the cathode. So H+ and Na+ will go this way. The
hydrogen gas bubbles up and is collected in the test tube. Pairs of H+ ions
will from H2 molecules.
The anions move towards the anode. Cl- is collected in the test tube - it
becomes Cl2 molecules, OH - also moves in this direction.
When the current is stopped the Na+ and OH- have no force holding them to
their respective electrodes, so they will form ionic bonds together, making
sodium hydroxide (NaOH).

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To test for hydrogen you first take the test tube, then seal it. Now you get a
wooden splint or match and light it. Quickly unseal the test tube and drop
the splint in. You should hear a 'pop' sound as the hydrogen combusts in a
rapidly exothermic reaction.
To test for chlorine you do the same as with hydrogen, but instead of a
match, you drop a damp piece of litmus paper into the test tube.…read more

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The purification of copper is a form of recycling, it is a way of obtaining new,
pure copper from old pipes, wires, circuits, and so on. It uses electrolysis.
A rod of pure copper is used as a cathode and the impure copper is an anode.
The electrolyte (solution the ions travel through) is a solution of copper (II)
sulphate (CUSO4).…read more

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All Sodium, Potassium and
Chlorides Except silver and lead, chlorides
All Ethanoates
Except calcium, barium and lead
All Nitrates
Sodium, potassium and ammonium
All other carbonates and hydroxides are
and hydroxides
Preparation of Soluble Salts
To prepare soluble salts you must form crystals of them.
Firstly you must react the reactants to get the soluble salt, if not already
Then the solution is passed through filter paper into an evaporating dish to
remove excess solid material.…read more

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Extraction of Aluminium (Aluminum)
Please note that this article uses the British English spelling of aluminium,
but this is exactly the same as aluminum - this is simply the North American
English spelling.
The Ingredients
Aluminium has a very high melting point and strong bonding between
atoms, so it doesn't readily dissolve in water. Instead, molten cryolite
(Na3AIF6) is used.
The Process
The pure aluminium is attracted to the cathode, which is a lining of graphite.…read more

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Some uses of aluminium are in making cars, trains, and bicycles because it is
reasonably strong but not too heavy so your aluminium bicycle won't break
and won't be too difficult to ride. Some packaging like foil and cans is also
made from aluminium - this is especially important in recying since many
drinks cans are made from steel - but this can be sorted using magnets. And
cooking utensils because it is very good at conducting heat so will evenly
warm the food.…read more


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