Oxidation and reduction
4 marks · Normal| Substance | Oxygen gained/lost |
|---|---|
| Sulphur dioxide | gains oxygen |
| Oxygen | no change |
| Potassium chloride | no change |
| Sulphur trioxide | formed from SO2 + O2 |
Which substance in the table is oxidised? Explain your answer.
Identify the oxidising agent in this process. Justify your choice.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) Sulphur dioxide is oxidised because it gains oxygen. · must show sulphur dioxide identified, reason: gains oxygen
(b) Oxygen is the oxidising agent because it provides oxygen for the reaction. · must show oxygen identified, reason: provides oxygen
Common mistakes: naming the wrong agent; not supporting answer
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Identifies sulphur dioxide as the substance oxidised.
B2 (a) · 1 mark · Gives correct explanation (because it gains oxygen).
B3 (b) · 1 mark · Names oxygen as the oxidising agent.
B4 (b) · 1 mark · Justifies choice (because it provides/gives oxygen to another substance).
Worked solution
a: Sulphur dioxide is oxidised because it gains oxygen during the reaction.
b: Oxygen is the oxidising agent because it provides oxygen that is added to sulphur dioxide.