Aluminum Foil Lab

Objective: Making alum called potassium aluminum sulfate dodechydrate, from aluminum and potassium hydroxide.
Materials: Aluminum foil weighing 1.0254 g ripped into small pieces, 250 mL beaker, Buchner funnel, filter paper, graduated cylinder, 25 Ml of 3 MKOH solution, Stirring rod, 35 Ml of sulfuric acid, 50 Ml of Aqueous ethanol solution.
Procedure: we started this experiment by gathering aluminum foil, in the lab manual it does not clearly state how small the piece of foil need to be, so we cut them into about the size of tomato’s diced. The total weight of our foil was 1.024 g. Placed into a 250 mL beaker and 25 mL potassium hydroxide solution added with the foil. Once the solution was added we noticed a large amount of heat, and gas coming

off the solution until finally the aluminum was dissolved. The solution at this point looked like gray water, and had a few little chucks of foil not broken up. In order to solve this, we then ran solution through the Buchner funnel twice and not the one recommended time in the lab manual. Once we ran the solution through the filter a second time we finally reached the desired color, of being clear. Next the lab manual advised to allow the solution to cool to room temperature, we waited a totally of 3 minutes but the solution was still slightly warmed when we continued.
Sulfuric acid was then added to the solution and total of 35.5 mL and stirred constantly.

While the sulfuric acid was, being added we noticed a milky clump start to form, better known as precipitate but once the sulfuric acid was added completely instead the solution was thicker and cloudy white, sort of like the early starts of mashed potatoes. Our solution still had larger clumps of product so we decided to do the optional piece placed into our lab manual, which is filter the solution again to remove the clumps out. Once we filtered the solution for the total of 3 times during this lab we found that we had roughly 58 mL of solution left. This solution we took and placed on a hot plate to a slow boil until we reached 50 mL left the beaker. We then allowed the beaker to cool to room temperature and placed the beaker into the ice bath. During the ice bath, we ran into some issues after the 15 minutes had passed we had hardly any crystal formation, so by the advice of the professor we scraped the bottom and the sides of the beaker and left the beaker in the ice bath for an additional 10 minutes. Finally, we poured the crystal through a filter and poured 50 mL of ethanol solution over the crystals.
Data: In the start of this lab we used aluminum foil weighing 1.0254 g, and the final weight of the product, 2KAl(SO4)2 * 12H20 + 3 H2 , was an actual yield of 6.3281 g. Once we finished this process we calculated the molar mass to find out the theoretical yield and the percent yield,

the molar mass of KAl(SO4)2 * 12H20 was 474.41 grams.
Once having the molar mass was continued to find a theoretical yield of 18.03 grams, making our percent yield 35.09 %.
Results: The final product produced was a lot less than our class mates given use only 35.09 %, we wondered if this could have been a series of mistakes such as filter more than recommend, not waiting for the product to reach room temperature or the issue in the ice bath in which the crystals themselves were having issues forming. The final product was a crystal soft substance that was white like snow, with an overall glitter appearance to it.
Conclusion: The fact that the percent yield was so low was a disappointment for me and my partner we both discussed what could have went wrong during the lab to produce such as low amount of product, the best idea we came up with was an issue with the heating process its self, because we filtered so many times we had little solution to boil, leading us to believe this was the reason for the low crystal production.
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