Does sodium carbonate react with an acid?
Yes. All carbonate and bicarbonate compounds react with acids to produce carbon dioxide and water. There are a couple of ways that I can think of to distinguish between carbonate and bicarbonate. That would be a good “after the exam” inquiry lab for my AP class. None of the ways involve color, except, perhaps, for the color of an indicator. The first would be stoichiometric. Equal masses of Na2CO3 and NaHCO3 will produce different amounts of CO2 with equal volumes of HCl at the same concentration. Since NaHCO3 has a lower molar mass, then there will be more carbonate in the same mass as Na2CO3, producing more CO2. The second way would be the pH of the solutions. The bicarbonate solution should have a lower pH.
