With a Rose Petal
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A rose petal is bleached by the sulfur dioxide.

With Permanganate
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The sulfur dioxide reduces dissolved purple permanganate to nearly colorless manganese(II).

Discussion
Sulfuric acid has a very high affinity for water. It is shown to dehydrate a carbohydrate (sucrose) forming carbon. Sulfuric acid is reduced to sulfur dioxide, which bleaches a rose petal.

In a second experiment, the sulfur dioxide reduces purple permanganate to nearly colorless manganese(II).