Chemical and Physical Changes Procedures
Post date: Nov 07, 2013 6:55:22 PM
Pre-Lab Procedures 3-3
1. Prepare a table to record your observations. Observations will basically describe before and after the procedure is completed. Below is an example. You should have produced this in class. (Here is a sample, which you should have started to create in class and should have finished for lab.
Procedure Observation Type of change
Heat Tooth picks
Sodium Chloride in water
Heat salt water
2. Break 5 tooth picks into small pieces and place them into a large test tube. Heat strongly. Record your observations.
3. Put 3g of sodium chloride into a small test tube. Add 2 mL of distilled water. Record your observations.
4. Setup a ring stand, iron ring, clay triangle, and crucible as seen on the front lab table.
5. Pour the salt solution from the test tube into a crucible and heat it until the water evaporates. Record your observations.
6. Let the crucible cool and add 2 mL of distilled water.
7. Use a thin-stem pipette to add 10 drops of silver nitrate. Use a magnifying glass to observe the resulting mixture. Record your observations.
8. Heat the solution until water evaporates. Observe the results with a magnifying glass. Record your observations.
9. Add 15 mL of ammonium hydroxide to the crucible. Record your observations.
10. Determine the mass of copper wire. Record the mass.
11. Place the copper wire in a small test tube. Add silver nitrate to cover the wire completely. Observe this reaction about 15 minutes before the end of the period. Record your observations.
12. After your observations have been recorded, determine the mass of the copper wire again. Record this mass.
13. Rinse and dry the crucible.
14. Place 1 g of CoCl2·6H2O (cobalt (II) chloride hexahydrate). Heat slowly and then more strongly. Record your observations.
15. Allow the crucible to cool.
16. Add 10 drops of water to material in the crucible. Record your observations.
Dispose everything but the cobalt solution down the drain. Place the cobalt solution in the marked beaker identified by the instructor.