Which is the best way to distinguish between aqueous solutions of sodium carbonate and ammonium carbonate and why?
Ammonium carbonate decomposes upon heating in aq. solution to produce carbon dioxide and ammonia, the latter gas can be identifed from its characteristic odour and also by using a moist red litmus paper. Red litmus turns to blue when it comes in contact with ammonia. The balanced chemical reaction for the decomposition is:
`(NH4)2CO3 (s) rarr CO2 (g) + H2O (l) + 2NH3 (g)`
Sodium carbonate is thermally stable upto a very high temperature. Therefore, this experiment can be utilised to distinguish between aqueous solutions of sodium carbonate and ammonium carbonate.
Heat both the test tubes containing abovementioned solutions and place a piece of moist red litmus paper at the mouth of both. The litmus paper which turns blue indicates the presence of ammonium carbonate in the corresponding test tube.