We can test for the carbonate ion by adding dilute
An acid is a substance that forms a solution with a pH value of less than 7. Acidic solutions contain an excess of hydrogen ions, H+(aq).
acid. If the gas given off turns limewater cloudy, then the test is positive. For example, if we add dilute hydrochloric acid to sodium carbonate, sodium chloride is formed and carbon dioxide gas – which turns limewater cloudy – is given off. The equation for this reaction is:
2 HCl(aq) + Na2CO3(s) 2 NaCl(aq) + H2O(l) + CO2(g)
The ionic equation is:
2 H+(aq) + CO32−(aq) H2O(l) + CO2(g)