Question

Near the endpoint of the Na2CO3 - HCl titration, it is necessary to heat the analyte solution almost to boiling to remove the _____ produced by the titration reaction.

a. sodium chloride
b. carbon dioxide
c. water
d. bicarbonate ion

Answer 1

During a Na2CO3 - HCl titration, the analyte solution is heated near the endpoint to expel the carbon dioxide gas produced in the reaction.

Step-by-step explanation:

Near the endpoint of the Na2CO3 - HCl titration, it is necessary to heat the analyte solution almost to boiling to remove the carbon dioxide produced by the titration reaction. During the reaction between sodium carbonate and hydrochloric acid, carbon dioxide gas is generated along with aqueous sodium chloride and water, as illustrated by the equation:

Na₂CO₃ (aq) + 2HCl(aq) → 2 NaCl (aq) + CO₂ (g) + H₂O (l)

Without heating, the carbon dioxide gas may remain dissolved in the water as carbonic acid or as bicarbonate ions. Heating helps to expel the carbon dioxide from the solution, which is necessary for properly determining the endpoint of the titration.