What are carbonate ions and how can you recognize them?

1 Answer
Mar 27, 2017

Well, carbonate ions are represented by #CO_3^(2-)#.


And how to demonstrate the presence of #CO_3^(2-)#?

Well, you must acidify the solution, and collect the evolved carbon dioxide.

The reactions that occur here are (i):

#CO_3^(2-) + 2H^(+) rarr CO_2(aq) + H_2O(l)#

And (ii):

#CO_2(aq) + Ca(OH)_2(aq) rarr CaCO_3(s)darr + H_2O(l)#

Precipitation of calcium carbonate is not straightforwardly observed, and if you do this in the lab, it is a good idea to use authentic carbonates so that you know for what you are looking.

The alkaline earths (Group 2) form binary carbonates that are (reasonably) insoluble in water.