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P-8
NOTE: The H2SO
4
solution must be replaced between each run. If the copper ion concentration builds
up in the H2SO
4
solution, Cu
2+
will be preferentially reduced at the nichrome cathode since copper ions are
more easily reduced than hydrogen ions. You should perform a third run if there were any problems with
either of the first two runs.
Part II. Spontaneous Reactions
A.
Place a tiny strip of zinc foil in one well of a spot test dish and add 4-5 drops of 0.10 M Cu(NO3)2
solution. Record your observations. What would you expect if you placed a small strip of copper foil
in 0.10 M Zn(NO3)2? Try this in another clean well to be sure. A more reactive metal displaces a less
reactive metal (ion) from solution. Which is more reactive, Cu or Zn? Record your conclusion on the
Observations Sheet.
B.
If a metal dissolves in acid, then it has displaced H2; it is more reactive than H2. To determine whether
Zn and Cu are more reactive than H2, put a tiny piece of each Zn and Cu into clean wells of the spot
test dish and add 4-5 drops of 6.0 M HCl to each metal. Record your conclusions on the
Observations Sheet.
Before leaving the laboratory, check to make sure that all of your equipment is clean, and in your drawer. As
well, all communal equipment must be clean and returned to the designated location in the laboratory.
