Question

Will it make a difference if use 45.0ml of water instead of 30.0 ml of water in a analysis of an antacid experiment?

Answer 1

Antacid contains bases like Mg(OH)₂, CaCO₃, NaHCO₃ etc. which are titrated with a standardized solution of HCl in the lab. HCl reacts with Mg(OH)₂ or CaCO3 on a 2:1 molar ratio. The reaction between HCl and NaHCO₃ takes place on a 1:1 molar ratio.

The number of moles of HCl used in the experiment remains the same; however, when 45.0 mL of water is used instead of 30.0 mL, the molarity of HCl reduces, i.e, we are working with a more dilute HCl solution. However, since the number of moles remain unchanged, the reaction will still proceed as per the above mentioned molar ratio. Therefore, the volume of HCl required to reach the equivalence point will be higher; however, the calculated molarity and hence, the mass of the base present in the antacid tablet will remain the same.