A student analyzed a CaCO3 antacid tablet by neutralizing the base with an excess of .60 M HCL and back-titrating the excess with .50M NaOH.

He recorded the following data:

mass of tablet = 1.3g

amount of active ingredient CaCO3 per label = 500 mg

volume of HCl added: 25 mL

initial buret reading : 34 mL

final buret reading : 47.4 mL

During neutralizing the antacid, CO2 was produced. It was removed by adding an excess of HCl into the solution and heating the mixture on a hot plate until boiling to remove the CO2.

If the CO2 is not removed from the solution by heating and remains during the titration with NaOH, would the determined mass of CaCO3 in the antacid tablet be too high or too low?