Lab 5 Essay

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Lab #5 – Exp #2: Evidence for Chemical Change Name: 
Period: 2
 Date Due: 1/27/12 Lab Partners: ______________________ Objective: • To observe the types of evidence that indicate a chemical change has taken place. • Infer from the observation of chemical change that a new substance has been formed. Procedures: 1. In the 250ml beaker, make a water bath by heating until boiling approximately 125 ml of water. 2. While the water bath is heating make three marks that are 1cm apart on a 13 x 100mmtest tube. Make the marks from the bottom up. 3. Add 1.0M copper (II) nitrate to the first mark on the test tube. 4. Add 1.5M sodium hydroxide to the second mark on the test tube. Mix with the stirring rod. Touch the bottom of the outside of the test tube to see if heat has been released. The copper-containing product is copper (II) hydroxide. The other product is sodium nitrate. 5. Put the test tube in the water bath begun in step 1. Heat it until no more change occurs. The products are copper (II) oxide and water. 6. Remove the test tube from the hot water bath. Turn off the burner. Cool the test tube and its contents for 2 minutes in room temperature water. Add 1.5 M hydrochloric acid to the third mark. Mix with the stirring rod. Rinse the stirring rod. The products are copper (II) chloride and water. 7. Place a 12 cm piece of aluminum wire in the test tube. Leave it until no more reaction is observed. Touch the bottom of the test tube to check for temperature change. Two reactions take place. Copper (II) chloride and aluminum produce copper and aluminum chloride. The aluminum also reacts with hydrochloric acid to form hydrogen and aluminum chloride. 8. Remove the write from the test tube. Compare the copper formed to a sample of copper wire. 9. Dispose of the solids and the liquids formed in
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