gcse revision document on electrolysis, detailed decription with images - contains all the information that you need to know for the addtional chemistry exam 

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  • Created by: Aimee
  • Created on: 27-04-11 18:46
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By Aimee
There are two diagrams above because one
shows the anode on the left side whilst the
other shows the anode on the right side.
The anode is the positive electrode whilst
the cathode is the negative electrode. Remember though that positive ions are
called cations whilst negative ions are called anions. The flow of electrons
always goes from the positive electrode 0 the anode to the negative electrode ­ the
The solution in which the electrodes are put in is called the electrolyte.
Electrolysis is the breaking down/ decomposition of a substance using electricity.
The electrolyte used are usually free ions dissolved in water, it is these free ions
that conduct the electricity.
When electrolysis happens, the least reactive elements are given off at the
electrodes, e.g. sodium chloride solution = so in this electrolysis
reaction, at the cathode, we would have hydrogen gas being released whilst at the
anode, we would have chlorine gas being given off. And then left in the solution
would be sodium hydroxide left.
The flow of electrons comes from the electrons being taken away from the negative
ions that come to the positive anode as they have extra electrons that make them

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By Aimee
negatively charged. So they lose these electrons which move round the circuit to
the cathode to where positively charged ions come to, then the electrons are given
to these element ions to make their charge neutral.
Electrolysis of different substances require
different metal electrodes, additionally, the
solution changes as well depending on the
substance being broken down.
For higher tier You may need to be asked to write the halfequations of an
electrolysis process.…read more


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