Extended Tier Only
A student is given two colourless solutions, S and T.
The student tests a portion of each solution with a few drops of acidified aqueous potassium manganate(VII), and a separate portion of each with aqueous potassium iodide.
The observations are shown.
solution | with acidified aqueous potassium manganate(VII) | with aqueous potassium iodide |
|---|---|---|
S | the purple colour disappears | no change |
T | no change | the solution turns brown |
State a conclusion about solution S.
Give the observation that supports it.
Extended Tier Only
State a conclusion about solution T.
Give the observation that supports it.
Name the substance that causes the brown colour when solution T is added to aqueous potassium iodide.
Extended Tier Only
A student writes that in this reaction "the potassium iodide is oxidised".
Explain why this answer is not precise enough.
Extended Tier Only
Explain why the student cannot reach a definite conclusion about what solution S is from the potassium iodide test alone.
Extended Tier Only
The student is told that one of the two solutions is aqueous potassium iodide.
Identify which solution is the aqueous potassium iodide.
Explain your reasoning.
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