Why conc.H2SO4can dry SO2gas ?

2009-04-03 7:11 am

Concentrated sulphuric acid is strong oxidizing agent while sulphur dioxide is reducing agent
However, it is found in text book that conc.H2SO4 can be used to dry moist SO2 gas as conc.H2SO4 is hygroscopic.

Shouldn't SO2 be oxidized???????
Why a reducing agent can pass throug a strong oxidizing agent without being reacted???????

回答 (1)

老爺子

2009-04-03 8:15 am

✔ 最佳答案

Concentrated sulphuric acid can not oxidize sulphur dioxide. There are two reasons:

1. Sulphur dioxide is a reducing agent only in the presence of water. The concentrated sulphuric acid used is 98% sulphuric acid, and the sulphur dioxide only contains a small amount of water. There is an insufficient amount of water.

2. If such redox reaction happened, sulphuric acid would be reduced sulphur dioxide, and sulphur dioxide would be oxidized to sulphuric acid. This is equivalence to no change.

Since there is no reaction between concentrated sulphuric acid and sulphur dioxide, thus concentrated sulphuric acid can be used to dry sulphur dioxide gas.
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