Final answer:
Firing the crucible prior to adding a hydrate is done to remove impurities, ensuring accurate experimental results by avoiding alterations in mass and unwanted variables in the reaction process.
Step-by-step explanation:
The purpose of firing the crucible before adding the hydrate is to remove impurities that may be present in the crucible. This is crucial because impurities can alter the results of an experiment by affecting the mass of the hydrate and interfering with the reaction. Firing the crucible ensures that any moisture and volatile compounds are burnt off, leaving a clean environment for the hydrate to decompose accurately when heated. This step does not enhance color, increase volume, or speed up the reaction directly; though, it is essential for obtaining accurate experimental results. Furthermore, firing can help to avoid introducing unwanted variables into the reaction that could influence the study of reaction rates, which are affected by factors such as molarity, temperature, and the surface area of reactants.