In Exp. 8, to determine the amount of CaCO₃ in an antacid tablet, the tablet is dissolved in excess hydrochloric acid. A back-titration is done to determine the amount of CaCO₃ in the antacid tablet. During the back titration, this setup requires a 50 mL burette suspended above a 250 mL Erlenmeyer flask. Identify the contents in the burette and in the flask and write the balanced equation for the net ionic reaction that takes place during the titration.
Select one:
A. The burette contains NaOH and the flask contains CaCO₃, HCl, and phenolphthalein indicator. The reaction is Ca₂⁺(aq) + 2OH⁻(aq) -> Ca(OH)₂(aq).
B. The burette contains HCl and the flask contains CaCO₃, H₂O, and phenolphthalein indicator. The reaction is CO₃²⁻(aq) + 2H⁺(aq) -> H₂CO₃(aq).
C. The burette contains NaOH and the flask contains CaCO₃, HCl, and phenolphthalein indicator. The reaction is Ca(s) + H₂O(l) -> Ca(OH)₂(aq).
D. The burette contains NaOH and the flask contains CaCO₃, HCl, and phenolphthalein indicator. The reaction is H⁺(aq) + OH⁻(aq) -> H₂O(l).
E. The burette contains HCl and the flask contains CaCO₃, H₂O, and phenolphthalein indicator. The reaction is Ca₂⁺(aq) + 2Cl⁻(aq) -> CaCl₂(aq).