Find the number of moles of hydrochloric acid in $40.0\,\text{cm}^3$ of $1.00\,\text{mol dm}^{-3}\,\text{HCl$.
Once the reaction was complete, the mixture was transferred to a volumetric flask and diluted to $100\,\text{cm}^3$. A $10.0\,\text{cm}^3$ aliquot taken from the flask needed $15.0\,\text{cm}^3$ of $0.050\,\text{mol dm}^{-3}$ sodium carbonate solution, $\text{Na}_2\text{CO}_3$, for all of the remaining hydrochloric acid to be neutralised.
Write the equation for the full reaction between sodium carbonate and hydrochloric acid.
Calculate the amount, in moles, of sodium carbonate required to react with the hydrochloric acid in the $10.0\,\text{cm}^3$ sample from the volumetric flask.
Calculate the amount, in moles, of hydrochloric acid contained in the $10.0\,\text{cm}^3$ sample.
Calculate the total amount, in moles, of hydrochloric acid left after the reaction shown in equation 1.
Use your answers to (a) and (b)(iv) to calculate the amount, in moles, of hydrochloric acid that reacted with the $0.50\,\text{g}$ sample of $M$.
Use your answer to (v) and equation 1 to calculate the amount, in moles, of $M$ in the $0.50\,\text{g}$ sample.
Calculate the relative atomic mass, $A_r$, of $M$ and identify $M$.