Final answer:
Using a volumetric flask allows for the preparation of a solution with a precise concentration by ensuring that a known mass of solute is dissolved in an exact volume of solvent.
Step-by-step explanation:
We dissolve our sample into a volumetric flask to ensure that we have a solution with a precise concentration. The volumetric flask is calibrated to a single, exact volume, and this allows us to know the exact volume of the solution after the solute has dissolved. Typically, we start by weighing the appropriate mass of solute, add a bit of solvent to dissolve it, and then add more solvent until the level reaches the calibration mark. This is crucial because the volume of a solution is not simply the sum of the volumes of the solute and solvent due to volume contraction, and in many cases such as preparing a 1.00 M NaCl solution, the hydrated ions take up space in the solution. Therefore, the volumetric flask enables precise dilutions and preparations, which is essential for consistent results in experiments and reactions.