The goal of this experiment is to determine the molecular formula of an unknown alkali (or alkali earth) metal sulfate, via application of gravimetric analysis. We used barium nitrate, due to the very low solubility of barium sulfate. We can then react all of the sulfate ions within the HCl solution with barium (which is added to excess, to ensure that all of the sulfate reacts), filter the solution (with ashless filter paper), rinse it thoroughly, burn the paper to isolate the precipitate, then measure the mass of the precipitate. This can be applied to determine the amount of an analyte within a sample of an unknown substance.
I hypothesize that with this data gathered, and knowledge of the molar mass of barium sulfate (and its constituent ions) we should be able to calculate the mass of the sulfate, and from that, the percentage of sulfate within the unknown alkali (or alkali earth) metal sulfate. With this data, we can cross reference the unknown sulfate with all the various possible alkali and alkali earth metal sulfate, and thus determine the one that is the most likely to be the unknown metal sulfate.