Lab 16 - Experiment 16: Synthesis of Alum The purpose of...

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Experiment 16: Synthesis of Alum The purpose of this experiment was to synthesize the inorganic salt alum from aluminum foil. To do this aluminum foil squares were broken down by KOH and H2SO4 and alum was formed according to the following reaction. 2Al(s) +2KOH + 22H2O +4H2SO4 → 2KAl(SO4)2·12H2O(s) + 3H2(g) The alum produced was then analyzed for the presence of Al,(3+) K(+), SO4(2-), and water. Alum crystals were grown via three different methods: from a seed crystal, via layering in ethanol and though vapor diffusion in ethanol. When KOH was added to the foil hydrogen gas bubbles formed and the solution turned milky due to the presence of an aluminum hydroxide ion. After adding sulfuric acid, a white aluminum hydroxide precipitate formed. The solution was heated and the precipitate dissolved. Then the solution was cooled and alum crystals formed in a radial pattern. The mass of the alum produced was 13.736g and the theoretical yield was 9.0576g. This gives a percent yield of 151.7%. It
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Lab 16 - Experiment 16: Synthesis of Alum The purpose of...

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