Evidence for a Chemical Change

Evidence for a Chemical Change

Names______

Evidence for a Chemical Change

Materials needed:

1 M HCl (hydrochloric acid)Iron Ring and Wire Gauze

1 M NaOH (sodium hydroxide)Permanent Marker

1 M Cu(NO3)2 (copper II nitrate) Ring Stand

Aluminum foil squareRuler

2 100 mL BeakersTest Tube

Bunsen BurnerGlass Stirring Rod

Procedure

  1. Place 50 mL of tap water into the 100 mL beaker and heat it until boiling, this will be the water bath used in step 5.
  1. While the water bath is heating, use the permanent marker and ruler to make 3 marks on the test tube. The first one should be 1 cm from the bottom. The second 2.5 cm from the bottom, and the third 4.5 cm from the bottom. Make the marks from the bottom of the test tube (closed end) moving towards the top. Be careful not to wipe these off.
  1. Add 1.0 M copper II nitrate to the first mark on the test tube.
  1. Add 1.0 M NaOH to the 2nd mark on the test tube. Caution sodium hydroxide is corrosive be extremely careful! Mix the solutions with a glass stirring rod. Rinse the stirring rod thoroughly before setting it down. The products of this reaction are copper II hydroxide and sodium nitrate. Touch the bottom to see if heat has been released by this reaction. Record any changes that occur in this reaction. ______
  1. Put the test tube into the water bath you prepared in step 1. Heat until no more change occurs. The product of this reaction are copper II oxide and water. Record any changes that occur in this reaction. ______
  1. Remove the test tube from the hot water bath. Turn off the burner. Cool the test tube and its contents for 2 min in room temperature water. Add 1 M HCl to the 3rd mark. Caution hydrochloric acid is corrosive be extremely careful! Mix with the stirring rod. Continue until no precipitate remains in solution. Rinse the stirring rod the new products are copper II chloride and water. Record any changes that occur in this reaction. ______
  1. Place a square of aluminum foil into the test tube, roll it into a cylinder but keep a lot of surface area (do NOT roll it into a ball). Leave it until no more reaction is observed (no more bubbling). Touch the bottom and check for temperature change. Two reactions take place. Copper II chloride and aluminum produce copper and aluminum chloride. The aluminum also reacts with HCl to form hydrogen and aluminum chloride. The hydrogen gas bubbles out, the aluminum chloride stays in the solution. Record any changes that occur in the test tube. ______
  1. Remove the aluminum foil from the test tube, compare the copper formed to the copper of a new penny. ______
  1. Dispose of the liquid and aluminum foil in a waste beaker. Clean all beakers and test tube and return everything to its proper place. Do not move anything that is still hot (ring stand and Bunsen burner). Wash your hands thoroughly before leaving the classroom.

Questions

  1. What are some of the causes of chemical changes?
  1. In what two ways is heat involved in a chemical change? Cite some specific examples from this lab.
  1. After step 7 of this experiment, where is the aluminum chloride?
  1. What is the color of copper containing solutions?
  1. Complete the following word equations (READ the procedure)
  2. copper II nitrate + sodium hydroxide 
  1. copper II hydroxide + heat 
  1. copper II oxide + hydrochloric acid 
  1. copper II chloride + aluminum 
  1. hydrochloric acid + aluminum 

  1. Balance each equation, and write the type of equation
  2. Cu(NO3)2 + NaOH  Cu(OH)2 + NaNO3
  1. Cu(OH)2  CuO + H2O
  1. CuO + HCl  CuCl2 + H2O
  1. CuCl2 + Al  Cu + AlCl3
  1. HCl + Al  AlCl3 + H2
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