how to use pH and HCl to distinguish HCO3- and CO32-?

add standard HCl to standard HCO3 - and CO3 2-, pH of CO3 2- is higher which means more alkaline. CO3 2- + H+ = HCO3 - is the first step, carbonate is converted into hydrogen carbonate. Then HCO3 - + H+ = CO2 + H2O.........so carbonate need twice the H+ than hydrogencarbonate to neutralize.

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