The limewater test is commonly used to detect carbon dioxide, but it is not a definitive test due to interference from sulfur dioxide. Both gases can cause limewater to turn milky, and excessive carbon dioxide can lead to the formation of calcium hydrogencarbonate, resulting in a clear solution. Therefore, the limewater test cannot reliably distinguish between carbon dioxide and sulfur dioxide. The discussion highlights the limitations of the limewater test and the need for more specific testing methods.
PREREQUISITESChemistry students, laboratory technicians, and professionals involved in gas analysis or environmental testing will benefit from this discussion.
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).