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B-7
C. Copper metal from copper(II) sulfate.
Pour the rest of the copper(II) sulfate from Part I into the evaporating dish of
Part III B. Wash the beaker with 1 or 2 mL of deionized water and add the washings to the evaporating
dish. The solution should be slightly acidic at this point. Add 4 mL of
6.0 M H2SO
4
to the solution and fill the evaporating dish with deionized water about two thirds full. Place
the evaporating dish on the hot plate and heat the solution to near boiling (i.e. steaming). Then add one
strip of metallic zinc into the dish and continue to gently heat the solution until the solution is colorless. If
the zinc strip becomes heavily coated with copper metal, gently stir the solution with a plastic stir rod to
dislodge the copper metal and expose the zinc metal surface or wash the copper off the zinc metal using a
fast stream of water from a wash bottle.
NOTE: If the solution is not colorless after all of the zinc has reacted, see your laboratory instructor.
If the volume of liquid in the evaporating dish drops below two thirds full, add deionized water to replace
the volume of liquid lost. Identify the substance that is lost as the liquid level decreases while the solution
is heated. Record your observations on your Observations Sheet.
D. Recovery of the copper metal.
Remove any unreacted zinc metal from the reaction solution and then add 2 mL of
6.0 M H2SO
4
and 5 mL of deionized water to the evaporating dish and heat on the hot plate for 5 minutes.
All of the zinc should have reacted with the H2SO
4
. Once gas evolution has stopped, isolation of the
copper metal can begin.
Set up a vacuum filtration system similar to the one used in Experiment A-Part II substituting a tiny
Hirsch funnel for the Buchner funnel and attaching the system to the water aspirator outlet rather than
the house vacuum. Pour the solution and the copper metal from the evaporating dish onto the center of
the filter paper. Use the plastic stir rod to push the metal onto the filter paper if necessary. Use deionized
water to remove all of the copper metal from the evaporating dish. When all of the liquid has drained
through the filter, wash the copper metal with 6 mL of 3.0 M HCl. Next, wash the copper thoroughly
with 20 - 30 mL of deionized water rapidly squeezed from a wash bottle to obtain a fast stream of
water.
