一條chem04年pastpaer既問題.

Jessica

2008-10-06 12:26 am

我想問
點解加左concentrated sulphuric acid落white sugar.佢會變black?
同埋
點解加左concentrated sulphuric acid落table salt.佢會變左colourless gas?

回答 (2)

Uncle Michael

2008-10-06 2:31 am

✔ 最佳答案

The answer is as follows:

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[匿名]

2008-10-06 2:24 am

1. Because of the dehydrating property of concentrated sulphuric acid, when the conc. H2SO4 is added into the white sugar(carbohydrate,HxCyOz), the H and O atoms in the white sugar will be removed so there is only carbon atoms remain in the sugar so that the colour of sugar turns black since carbon is black.
2.Concentrated sulphuric acid is a strong oxidizing agent, which can react with the reducing agent.When conc. H2SO4 is added to the table salt, the strong oxidizing agent:conc.H2SO4 will react with the weak reducing agent: Chloride ion and form the Chlorine gas.
Equation: 2Cl-(aq) --->Cl2(g) + 2e-
But I think the Cl2 is not in colourless, it should be green.
By Jimmy C.

參考: By Jimmy C.

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