Alum was synthesized from aluminum foil using the following procedure: The mass of a weighing paper was determined and recorded. A weight of about 0.45-0.5g of 1 x 1 cm pieces of aluminum foil were cut and transferred to the weighing paper and the total weight of both the weighing paper and the foil pieces determined and recorded in the data sheet. The foil was transferred into a labelled 150 ml beaker.
The beaker was transferred into a fume chamber and a 3M Potassium Hydroxide (KOH) solution was added into the beaker. The reaction was allowed to proceed for a few minutes until the formation of bubbles fizzled out. A solution of 4M Sulfuric Acid (H 2 SO 4) was added into the beaker slowly then heated slowly in a hot water bath until the formed precipitate dissolved.
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The mixture was then allowed to cool while stirring until crystals were observed. Vacuum filtration was used to obtain the crystals from solution. The crystals were rinsed using cooled 95% Ethanol and dried, the weight of the dried crystals was determined to obtain the actual yield. The theoretical % yield was determined based on the initial weight of the aluminum foil used.
Chemistry of Aluminum
The Amphoteric nature of Aluminum was demonstrated by reacting it with 6M Hydrochloric Acid and 3M Potassium Hydroxide solutions separately in a fume chamber. In both cases, bubbles were observed indicating evolution of Hydrogen gas.
Reaction of Aluminum with 3% Hydrogen Peroxide did not yield any observable changes. This indicates the resistance of the metal to corrosion via oxidation reactions. Furthermore, 3% Hydrogen peroxide has a weak oxidizing potential.
Aluminum was reacted with a solution of Copper (II) Sulphate.The solution slowly decolorizes from blue to colorless and a red-brown precipitate is observed. Aluminum is more active than Copper in the Reactivity series of metals, it is therefore able to displace Copper from its salt solution with formation of Aluminum Sulphate which is colorless.
