Describe how a pure, dry sample of sodium chloride could be prepared by reacting sodium hydroxide solution with dilute hydrochloric acid. Include in your answer how you would determine the exact volume of acid required.

1. Prepare a 0.1 M NaOH solution and a 0.1 M HCl solution.
2. Add the HCl to the NaOH until the solution turns colourless (using a pH indicator such as phenolphthalein). The volume of HCl at this point is the exact amount needed to neutralise the NaOH.
3. Repeat the titration with the same volumes of NaOH and HCl but without any indicator to confirm the stoichiometry.
4. Evaporate the resulting NaCl solution by gentle heating until a small, saturated volume remains, then allow it to cool. Filter the crystals and dry them in a warm oven or between filter paper.

This yields a pure, dry sample of sodium chloride.