Final answer:
Without boiling during a Na2CO3 - HCl titration, more HCl titrant will be required than the correct value due to the interference of CO2, which is not removed.
Step-by-step explanation:
If the boiling near the end of the Na2CO3 - HCl titration is not done, the amount of HCl titrant required will be greater than the correct value. The boiling process ensures the removal of carbon dioxide (CO2), which can interfere with the endpoint detection of the titration. By not boiling, CO2 remains in the solution and reacts with the titrant, therefore requiring more titrant to reach the endpoint, thus skewing the results higher than they should be. Boiling drives off the CO2 produced in the reaction between Na2CO3 and HCl, making sure that when the indicator changes color it is truly indicating the neutralization of HCl alone and not a mixture of HCl and unreacted CO2.