Recycling Aluminum Lab - Results and Discussion Alum was...

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Results and Discussion Alum was synthesized from the aluminum of a soft drink can by performing a series of chemical reactions and using gravity and vacuum filtrations. The amounts of reactants to be used in the process of synthesizing alum were provided in a tentative procedure. This procedure was scaled down in order to produce a theoretical yield of 23 g of alum. The purity of the crystallized and isolated alum was tested by determining its melting point and comparing it to the known melting point of pure alum. In order to produce a theoretical yield of 23 g of alum, a 1.311 g sample of aluminum was collected by using an electronic balance to find the mass of small strips of aluminum cut from a soda can. The small aluminum strips were placed in a 100 mL beaker. 66 mL of 1.4 M KOH solution was measured using a different 100 mL beaker and was poured into the beaker containing the aluminum. The beaker containing both the 1.311 g of aluminum and 66 mL of 1.4 M KOH was heated on a hot plate for 15 minutes. The aluminum strips had one shiny silver-colored side and one side colored with ink. The 1.4 M KOH solution appeared colorless and had a low viscosity. When these two reactants were heated together on the hot plate bubbles rose from the aluminum strips for the entire duration of heating. Yellow and green flaky solids could be seen floating at the surface of the solution. The solution became a dark brown color which progressively got darker during the duration of heating. The amount of solid aluminum appeared to decrease over time. The following chemical reaction occurred: 2 Al( s ) + 2 KOH ( aq ) + 6 H20 ( l ) 2K + ( aq ) + 2 Al(OH) 4 - ( aq ) + 3 H 2 ( g ) The beaker was removed from the hot plate after 15 minutes and allowed to cool to room temperature. Bubbling and fizzing continued for approximately 10 minutes and became progressively slower and less prominent. When the bubbling and fizzing ceased, the solid residue was removed from the solution using gravity filtration. The residue that was left in the filter paper was rinsed twice with 6.5 mL of distilled water measured in a 25 mL graduated cylinder. The filtered solution was collected in a 200 mL beaker and appeared colorless, had no apparent odor, and had very low viscosity. 27 mL of 9.0 M H 2 SO 4 was then measured in a 100 mL beaker. H 2 SO 4 is a colorless solution with low viscosity. Using a 25 mL graduated cylinder, 6.6 mL of this 9.0 M H 2 SO 4 solution was then added to the beaker containing the filtered solution, while the solution was gently stirred with a stirring rod and heated on a hot plate. The solution became a faint cloudy white color. The following chemical reaction occurred: Al(OH) 4 - ( aq ) + H + ( aq ) Al(OH) 3 ( s ) + H
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This note was uploaded on 10/19/2008 for the course CHEM 2070 taught by Professor Chirik,p during the Fall '05 term at Cornell University (Engineering School).

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Recycling Aluminum Lab - Results and Discussion Alum was...

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