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Similarities:
 The electrolyte is the substance that conducts electricity within the cell.
Electric charge is carried by anions to the anode and by cations to the
cathode.
 The electrode where oxidation occurs is called the anode.
 The electrode where reduction occurs is called the cathode.
 In the external circuit, electrons travel through the wire from the anode to the
cathode.
Key ideas of electrolysis:
The products of electrolysis depend on:
 The reactivity of the ions present
 The type of electrode used
 The concentration of the reactants
 The amount of current used
 The temperature
e.g. molten NaCl produces Na and Cl2
dilute aqueous NaCl produces H2 and O2 (as for H2O)
For electrolytic cells:
 Oxidation takes place at the anode (sign +ve)
 Reduction takes place at the cathode (sign –ve)
 Electrons flow from the anode to the cathode
 Electric current is used to cause a chemical reaction
 The applied voltage must be greater then the voltage of the cell
 If more than one reaction is possible the following rules apply
Metal ions:
Whether a metal is produced depends on its position in the reactivity series relative
to the position of water. In a concentrated solution the metal will form if it is below
water in the activity series. If it is above water, hydrogen gas forms. If there are 2
possible products, the one lower on the activity series will form.
Non-Metal ions:
A simple ion will always form its element. If a polyatomic ion is present, oxygen will
form in preference.