Data Bases • Custom Term Papers • Free Term Papers • Free Research Papers • Free Essays • Free Book Reports • Plagiarism? Links • Top 100 Term Paper Sites • Top 25 Essay Sites • Top 50 Essay Sites • Search 97,000 Papers @ DirectEssays.com • Search 101,000 Papers @ ExampleEssays.com • Search 90,000 Papers @ MegaEssays.com Free Essays • Term Paper Sites • Chuck III's Free Essays • Free College Essays • TermPaperSites.com • Free Essays • My Term Papers • Essay World • Planet Papers	Search Lots of Essays Back to Subjects - Science final lab final lab Purpose: To identify the unknown substance by characteristic properties. * 30g white substance * thermometer * 40mL water * 4 evaporating dishes * safety goggles * 10mL graduated cylinder 2.) Seperate your 40mL of water into 4 different test tubes, 10mL in each. 3.) Divide your 30g of white substance into the 4 test tubes evenly. You should put 7.5g into each test tube along with the water. 4.) Set up your apparatus as shown below: 5.) One at a time, place your test tubes in the water bath and heat the first test tube to 25 , the second to 50 , the third to 75, and the last to 100 degrees c. Remeber to stir with your stirring rod every so often. 6.) Mass your 4 dry evaporating dishes. 7.) After you have heated them to the right temperatures, pour the excess water into a dry evaporating dish. ( Be sure not to get any of the substance in your solution. ) 8.) Boil off the water, using the same apparatus as in step 4. 9.) Repeat steps 7 and 8 for the other 3 test tubes. 10.) Mass the evaporating dish and it's contents. 11.) Subtract the mass of the evaporating dish from the mass of the evaporating dish and it's contents. Multiply that number by 10 to get the solubilty in grams per 100 cm3 of water. 12.) Plot your graph and use the curve to identify what substance you had. Temp: Mass of evap. dish: Mass of evap dish+contents: Mass of contents: Solubility g/100cm3 water 25c 67.75g 69.69g 1.95g 19.5g 50c 65.31g 68.92g 3.61g 36.1g 75c 64.49g 69.18g 4.69g 46.9g 100c 67.83g 70.22g 7.38g 73.8g * If the solubility curves differ a lot, then chances are, your substances are different. * You would look at the graphs and find out which had a larger solubility, and then boil them in water for 5-10 minutes, then put the solution into an evaporating dish and boil off the liquid. The one with the higher solubility is the substance in the dish. * You could compare it to the other solubility curves and which ever one it is more like, is most likely the same substance. You could also look at the characteristic properties, such as solubility. According to the data that was produced, the substance that we worked with ( substance A ) is potassium nitrate. Bibliography: Word Count: 433
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