chem organic chem

Both statements are false.

Sulphur dioxide can change acidified potassium dichromate solution from orange to green. This is because sulphur dioxide oxidizes orange acidified dichromate ions to green chromium(III) ions.
3SO2(g) + Cr2O72-(aq) + 2H+(aq) → 3SO42-(aq) + 2Cr3+(aq) + H2O(l)

Although ethene can decolorize acidified potassium permanganate solution, ethene does not react with acidified potassium dichromate solution.

Therefore, acidified potassium dichromate can be used to distinguish between sulphur dioxide and ethene.
=

2009-07-01 14:31:46 補充：
In paragraph 2, "This is because sulphur dioxide oxidizes ...." should be "This is because sulphur dioxide reduces ...."

2009-07-01 14:33:05 補充：
To 冷風：
Sulphur dioxide does not react with acidified potassium dichromate solution. Please refer to text books.

老爺子..你寫錯野喎

sulphur dioxide oxidizes orange acidified dichromate ions to green chromium(III) ions

應該係sulphur dioxide reduces orange acidified dichromate ions to green chromium(III) ions.
chromate(VI) is reduced by sulphur dioxide, 所以sulphur dioxide 還原它, 不是氧化它

2009-06-30 17:38:31 補充：
我唔明喎

ethene does not react with acidified potassium dichromate solution.

點解ethene唔可以同acidified K2Cr2O7反應?

應該react到先真