Ap Chem Lab 4 Analysis of Alum

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1) Heading
a. Analysis of Alum
b. September 8,2010 – September 10,2010
c. Asad Mehmood
d. Lab Partner: Alec Drey, Sarah Schrader, Seth Kerrey 2) Purpose
e. Research Problem: Is what we have alum? In this lab, we will be analyzing alum by doing three different tests. The first will be to find the melting point, the second to find the amount of water in alum, and the third is to find the percent sulfate. We expect the values to be close to the actual. f. Variables:

i. Independent
1. The temperature the hot plate was at
2. The amounts of alum used
3. The temperature heated at
4. The number of times filtered
ii. Dependent
5. The time in which the compound melted and the melting point calculated 6. The amount that we get back after the experiment 7. Growth of particles
8. The amount of particles caught
iii. Control
9. Room Temperature
10. Lighting
11. Type of water solutions used
12. Materials stayed constant including weighing machine (Fisher) 3) Materials and Procedure
g. Materials
iv. Part 1:
13. Alum crystals, capillary tube, water bath, beaker (250mL), rubber band, metric ruler, watch glass, glass tubing, universal clamp, thermometer, hot plate, mortar and pestle, wax paper, balance, safety goggles v. Part 2:

14. Alum Crystals, evaporation dish, ring stand, iron ring, Bunsen burner, wire screen, crucible, crucible tongs, balance, safety goggles vi. Part 3:
15. Alum crystals, deionized water bottle, stirring rod, rubber policeman, graduated cylinders (25mL and 50mL), Hot Plate, Watch Glass, Beaker (250mL), Barium Nitrate, Balance, Drying oven, masking tape, safety goggles h. Procedure

vii. The Procedure is also located back in the lab manual. viii. Part 1:
16. For this portion of the lab, take some of the alum you have and then crush it into a fine powder and then using a capillary tube, put about a centimeter of the crushed alum into the capillary tube. Put the capillary tube into a glass tube so that the alum powder can be forced to the bottom of the capillary tube. Now attach the tube to the bottom of a thermometer using a rubber band and put that into a beaker of water that is partially boiling on a hot plate. The capillary tube should not be completely submerged. Then after a while, the alum will melt and you will have a temperature reading. ix. Part 2:

17. So first we will measure out about 2 grams of alum and then put that in the crucible. Put the lid on top of it and then put the crucible on an iron stand over the Bunsen burner with a cold flame for about 7-8 minutes. Then switch the flame to a hot flame and then keep on the stand for an additional 5 minutes with the hot flame. Once the alum is cooled, put the alum in a weighing boat and then measure the weight of the alum. x. Part 3:

18. Now for this part of the lab, first measure out about a gram of alum and then pour that into about 50mL of distilled water and mix until the alum is completely dissolved. Next pour about 35mL of the Barium Sulfate into the mixture and there will be a result of a white precipitate. Next heat on barely boiling on a hot plate for about 15 minutes with an evaporating dish on top of the beaker. Then remove and let it stand overnight. The next day, filter the liquid through a Buchner funnel with 2 filter papers and then allow the filter paper and the particles to dry on an evaporating dish in a drying oven. The next day weigh for the mass of the particles collected on the filter paper. 4) Safety

i. There are various safety issues in this lab. First of all we will be working with hot glass and as we know, a hot glass and a cold glass don’t look...
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