Limewater Test: Dedicated Test for Carbon Dioxide

[abcd8989]

Carbon dioxide and sulphur dioxide both can turn limewater milky. Either the presence of carbon dioxide and sulphur dioxide can give a positive test result. Why limewater test can be a dedicated test for carbon dioxide?

 

[alxm]

Why limewater test can be a dedicated test for carbon dioxide?

It isn't. (But if you pass SO2 through it long enough, it will form CaS and become clear again, so in this particular case, it can be a test if you have enough gas.)

 

[abcd8989]

It isn't. (But if you pass SO2 through it long enough, it will form CaS and become clear again, so in this particular case, it can be a test if you have enough gas.)

If excess amount of carbon dioxide is bubbled into limewater, a clear solution can also be formed (calcium hydrogencarbonate formed). So, excess gas also cannot distinguish between sulphur dioxide and carbon dioxide. I wonder why we usually conclude that carbon dioxide is present if a positive result is shown in limewater test, ignore that it is the presence of sulphur dioxide leading to the positive result.

 

[chemisttree]

If excess amount of carbon dioxide is bubbled into limewater, a clear solution can also be formed (calcium hydrogencarbonate formed).

Not true. You will never make a bicarbonate of calcium. It just doesn't happen. ... as a solid anyway.