five indigestion tablets containing calcium carbonate with a total mass of 2.50g were added to 50.0cm^3 of 1.00mol dm^-3 hydrochloric acid.
CaCO3+2HCl--> CaCl2+CO2 +H2O
after reaction the solution was transferred to a 250cm^3 volumetric flask and the volume made up to 250cm^3 using deionised water. 25.0cm^3 samples of the solution were titrated against 0.126mol dm^-3 sodium hydroxide solution. The average titre was 11.30cm^3.
a) calculate the mass of calcium carbonate (in grams) in the five tablets. Give your answer to 3 significant figures.
b) calculate the percentage of calcium carbonate in the tablets.