Chemistry Lab Report Experiment 5
中秋对联
指甲裂了怎么办Eric Zhang 11/2/06
AP Chemistry Carlock 4°
成衣店A. Qualitative determination of water
I. Purpo
The purpo of experiment A is to dehydrate a known hydrate to determine its percent composition and the mole coefficient in the formula.
II. Materials and Equipment
1. Finely ground copper(II) sulfate pentahydrate (CuSO4 · 5H20)
2. Cobalt chloride test paper
3. Clay triangle
4. Crucible
5. Crucible cover
6. 25x200mm hard-glass test tube
III. Procedures
1. Fold a 2.5x20cm strip of paper lengthwi to form a V-shaped trough or chute
2. Load about 4g of finely ground copper(II) sulfate pentahydrate in this trough, spreading it evenly along the length of the trough
3. Clam a dry 25x200mm hard-glass test tube so that its mouth is 15-20 degrees above the horizontal
4. Inrt the loaded trough into the tube
5. Rotate the tube to a nearly vertical position to deposit copper(II) sulfate in the bottom of the tube
6. Tap the paper chute gently if necessary, but make sure that no copper sulfate is spilled and adhering to the sides of the upper part of tube
7. Remove the chute and turn the tub until it slants mouth downward at an angle of 15-20 degrees below the horizontal
8. Make sure that all of the copper(II) sulfate remains at the bottom of the tube
9. To obtain a sample of the liquid that will conden in the cooler part of the tube, place a small clean, dry test tube, held in an upright position in either a rack or an Erlenmeyer flask, just below the mouth of the tube containing the hydrate
10. Gradually increa the rate of heating, noting any changes that occur and collecting some of the liquid that condens in the cooler part of the tube
11. Continue heating until the blue color of the hydrate has disappeared
12. Finally warm the tube over its entire length, without directly applying the flame to the c
lamp, for a minute or two to drive off most of the liquid that has condend on the inner wall of the tube普通话分级
汤圆怎么做好吃13. Allow the tube and contents to cool
14. 儿童的高跟鞋Obrve the appearance and odor of the liquid that has been collected
15. While the tube is cooling, dry a piece of cobalt chloride test paper by holding about 20 to 25 cm above a burner flame; that is clo enough to heat but not clo enough to char or ignite the paper. When properly dried, the test paper should be blue.
16. Using a clean stirring rod, place a drop of the liquid collected from the hydrate on the dried cobalt chloride test paper
17. For comparison place a drop of distilled water on the cobalt chloride paper. Record the obrvations
18. Empty the anhydrous salt residue in the tube onto a watch glass and divide it into two portions
19. Add 3 or 4 drops of the liquid collected form the hydrate to one portion and 3 or 4 drops of distilled water to the other.
20. Compare and record the results of the tests.
IV. Cautions
1. 贵用英语怎么说Wear protective glass
2. Heat the hydrate gently at first to avoid excessive spattering
3. Do not heat until the residue in the tube has turned black
4. At excessively high temperatures (above 600°C) copper(II) sulfate decompos; sulfur trioxide is driven off and the black copper(II) oxide remains as a residue
V. Hypothesis
The collected liquid from the dehydrated copper(II) sulfate will be result in the obrvation of the hydrate being 40% water
B. Quantitative Determination of Water in a Hydrate
I. Purpo
The purpo of experiment B is to determine the quantity of water in an unknown hydrate.
II. Materials
1. Unknown hydrate
2. Clay triangle
形容速度快的诗句3. Crucible
4. Crucible cover
III. Procedures
1. Obtain a sample of an unknown hydrate, as directed by your instructor
2. Be sure to record the identifying number
3. Accurately weigh a clean, dry crucible and over
4. Place between 3 and 4g of the unknown in the weighed crucible, cover, and accurately weight the crucible and contents
5. Place the covered crucible on a clay triangle; adjust the cover so that it is slightly ajar to allow the water vapor to escape; very gently heat the crucible for about 5 minutes
6. Readjust the flame so that a shapr, inner-blue cone is formed
7. Heat for another 12 minutes, with the tip of inner-blue cone just touching the bottom of the crucible
8. The crucible bottom should become dull red during this period
9. After this first heating is completed, clo the cover, cool (about 10 minutes) , and weight
10. Heat the covered crucible and contents for and additional minutes at maximum temperatures; cool and reweigh
11. The results of the last two weightings should agree within 0.05g
12. If the decrea in weight between the two weightings was greater than this amount, repeat the heating and weighing until the results of two successive weightings agree to within 0.05g
