Question

What are carbonate ions and how can you recognize them?

Answer 1

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

Explanation:

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.