Michael Thomas Harbuck			Preparation and Analysis of an Alum
CHEM 2045C  						
Mrs. Deo 28/10/2007

I.  Preparation and Analysis of an Alum

II.  The purpose of the lab is to  synthesize, crystallize a solid product.  This product must be collected, measured quantitivly for yield and 	percent yield.  Finally the melting point of the product mass must be determined.  

III.  Procedure - The first day fo the lab a sample of aluminium in the form of an aluminium beverage can was created by cutting the 	available Al with snips and scissors.  These small pieces are then added to approximately 50ml of potassium hydroxide solution. \	This heterogeneous solution is then heated, allowing the Al to react with the KOH, forming Al ions in solution.  Hydrogen gas is a product of the reaction and is visible as bubbles.  

	Al(elemental) + KOH(aq) ------>  AL+  + H2 + K+ + OH-

	This solution is then filtered with an appropriate paper filter into a 250ml beaker and allowed to cool.  After cooling 20ml of 9 Molar 	H2SO4 (Sulfuric Acid) is added, stirring slowly.  Al(OH)3 forms as a white precipitate.  The first day of the lab ended here and the 	beaker was stored in the lab drawer until the following class period.  

	Upon arrival to the next class the purported large crystals had not formed in the beaker.  Then the beaker was cooled with ice and water bath until approx. 15 minuites later small crystals formed.  This was filtered and weighed as the first yield. Concurrently the remaining supernatant was heated to half reduction of volume.  Again the solution was cooled with the ice and water bath.  This second yield appeared, again at approximately 15 minutes. This second yield was filtered using the Buchman Vacuum filter with a pre-weighed filter paper.  The remaining supernatant is disposed of properly as waste.  

	The melting point of the alum crystals was then determined using the MP apparatus.  

IV Calculations  -Data
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	Amount of Start Al				 0.9899 (g)
	First Yield
	Watch glass + Product + FP		50.1244 	
  	WG 1						44.8250
	Filter Paper					   .2164
							  5.0830						

	Second Yield
	Watch glass + Product + FP		45.2388
	WG 2						44.6475
	Filter Paper					    .2175
							    .3735

	Actual Yield 					  5.4565(g)

	Theoretical Yield				1:1 
							Moles Al start: .9989g/26.982
								0.036686 Mol Al

							Moles KAl(SO4) = 5.4565g/162g MM =
								0.033653 Mol KAl(SO4)

	Percent Yield 				.033653/.036686  (100%) = 91.73 %

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Melting Point deg. C of Product Potassium Alumunium Sulfate

Sample 1 	start					66.5 deg. C
		finish					91.5 deg. C

Sample 2	start					84.0 deg. C
		finish					90.5 deg C

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V - Conclusion 

	The alum lab was fun.  Although no large crystals were obtained in the first run, it was surprising how much was synthesized, yielding almost 92 % from the start quantity of Al used in the reaction.  It would be interesting to find the used for the double salt, and learn how they are applied to everyday situations.  Heat, energy or the lack thereof, play a large role in chemical reactions.  Everyday items contain "fuel" for reactions as well!

	The melting point may be useful in determining the purity of a product, as well as identifying the product itself.