The discussion revolves around the limewater test as a method for detecting carbon dioxide, specifically questioning its reliability as a dedicated test given that both carbon dioxide and sulfur dioxide can produce similar results. The scope includes conceptual clarification and technical reasoning regarding the chemical reactions involved.
Participants express differing views on the reliability of the limewater test for carbon dioxide detection, with no consensus reached regarding its specificity or the chemical reactions involved.
The discussion highlights limitations in understanding the chemical reactions and conditions under which limewater may yield positive results for different gases, as well as the assumptions regarding the formation of calcium compounds.
abcd8989 said:Why limewater test can be a dedicated test for carbon dioxide?
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.alxm said: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 said:If excess amount of carbon dioxide is bubbled into limewater, a clear solution can also be formed (calcium hydrogencarbonate formed).