How to determine calcium trioxocarbonate (IV) content in a chalk by back titration

Answer 1

The steps to follow are as follows: First, mass the chalk, and add acid.
a) find the moles of original acid in the 100 mL added (normally on the label)
b) find the moles of NaOH used to titrate the excess acid
c) find the moles of HCl which the NaOH in (b) neutralized (ie. the moles of HCl which were titrated)
d) By subtraction from the total moles of acid in the 100 mL calculate how much acid reacted with the carbonate, hence the moles of CaCO3 and mass of CaCO3.
e) convert that mass of CaCO3 to precentage in the original chalk.

Answer 2

Good