$\ce{CO3^2-}$can be identified by their reaction with dilute acids. When carbonate ions react with a dilute acid like hydrochloric acid, they produce carbon dioxide gas:

To test for carbonate ions in a solution:

1. Add dilute hydrochloric acid to the solution.
2. Collect the gas produced and bubble it through lime water$\ce{(Ca(OH)2}$.
3. If the lime water turns cloudy, carbon dioxide is present, indicating the presence of carbonate ions in the original solution.