The objective of this lab is to run tests on a compound and analyze the substance itself, and then determine whether or not the compound is actually alum.
November 19, 2013
Laurel Hergenroeder and Sarinah Martelli
The purpose of this experiment is to run various tests on the substance called alum. (AlK(SO4)2 ∙ 12H2O). These tests like the process of filtration heating the solution will reveal things such as melting point, percent hydrate, as well as percent sulfate. After the experiment, the experimental mole ratio of alum to water will be calculated and then compared with the accepted mole ratio. (This is 12 to 1).
If this lab if conducted properly, the unknown substance will be determined to be alum because of melting point, percent hydration and percent sulfate. The first test that will be run has the purpose of revealing the alum’s melting point. Melting is defined as, the temperature at which a solid turns into a liquid. The melting point will help determine if the substance is an alum if its melting point is around 92.5° because this is the accepted melting point of an alum.
Then, the water will be evaporated from the substance, which will make it possible to find the percent hydration of the alum. A hydrate is a compound containing water: a chemical compound containing water molecules that can usually be expelled by heating. Anhydrous also will be a part of this lab because an anhydrous means to be with no water: describes compounds that contain no water, or crystals that lack chemically bound water of crystallization. The water will be expelled from the substance and begins hydrated but is then anhydrous because it will have no water in the end. Since the mass of the alum will be recorded before as well as after the water is evaporated, the two measurements will simply be divided (the larger as the denominator), yielding the percent hydration.