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Lab 2 - possible unknowns than comparing it to the percent...

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Arghaya Dalapati Arren Washington Lab 2 September 17, 2009 Discussion for Lab 2 Scenario 1 The purpose of the experiment was to identify an unknown hydrate and analyze the ability for the unknown to hold water by simply determining its % water composition. This was easily calculated by heating the unknown (Unknown D) 3 times, in a crucible for 15 minutes each interval. The water molecules were slowly converted into gas form, following the conservation of mass law, in essence evaporating all the water that comprised the unknown. Since the original mass was .506 grams and the remaining mass was .250, it was determined that there was 50.6 percent water by using the formula (Original Mass – Final Mass)/(Original Mass). This was determined by using some elementary logic, since the Final Mass is equal to the Original mass minus all the water. Once the percentage of water was found, the Identity of Unknown D was found by calculating the percentage composition of water in all the
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Unformatted text preview: possible unknowns than comparing it to the percent of water in Unknown D. The complete analysis determined that Bischofite was the hydrate (MgCl2*H20). Scenario 2 The purpose of this experiment was to determine if Fe2+ or Fe3+ was being reacted against Copper Sulfate. We figured out the amount of Copper Sulfate needed to react with Fe2+ and then placed a little bit more than that amount. 1g of Fe2+ needed 2.858 g of Copper Sulfate to react while 1g of Fe3+ needed 4.287 g. Thus we put in 3 grams of Copper Sulfate, which was a point in-between both Fe3+ and Fe2+. The solution turned clear and there was no excess iron, so the steel wool was Iron (II). This was because all the Iron reacted. If there were excess iron, then the unknown would have been determined to be Iron (III)...
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