In a similar experiment to yours, one tablet of Antacid A is titrated to its endpoint with 15.5 mL of 0.5 M HCl and one tablet of Antacid B is titrated to its endpoint with 24.3 mL of 0.5 M HCl. Which is the more effective antacid?

Answer 1

If you wish to do the math I would use
M x L = moles for each, then the one with more moles wins. But you don't need a calculator. Since the concn of the HCl is the same at 0.5M, then the one that takes more HCl to neutralize is the better neutralizer (although I don't know that that means it is more effective).