Define oxidation in terms of electron transfer - Leaving Cert Chemistry - Question b - 2009
Question b
Define oxidation in terms of electron transfer.
The electrolysis, using inert electrodes, of aqueous potassium iodide, KI, to which a few drops of phenolphthalein i... show full transcript
Worked Solution & Example Answer:Define oxidation in terms of electron transfer - Leaving Cert Chemistry - Question b - 2009
Step 1
Define oxidation in terms of electron transfer
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Answer
Oxidation is defined as the process of loss of electrons from a substance. During this process, the oxidation state of the substance increases.
Step 2
Name a suitable material for the electrodes
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Answer
A suitable material for the electrodes is platinum or carbon (graphite).
Step 3
Write balanced half equations for the reactions that take place at the electrodes
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Answer
For the anode reaction:
2I−→I2+2e−
For the cathode reaction:
2H2O+2e−→H2+2OH−
Step 4
Explain the colour change observed at the positive electrode (anode)
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At the positive electrode (anode), iodine is produced. The phenolphthalein indicator changes colour due to the presence of iodine, which can be observed as a red, orange, yellow, brown, or a combination of these colours. This is because iodine has a distinct colour that indicates its formation during the electrolysis process.
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