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A-7
While the copper(II) carbonate is forming, set up a Buchner funnel to filter the precipitate. A model of the
apparatus is displayed on the instructor’s laboratory bench. Put a sheet of filter paper (5.5 cm) in the
Buchner funnel, dampen it with a small volume of cold deionized water from your wash bottle and turn on
the vacuum so that the filter paper seals the holes in the Buchner funnel. The filter paper must remain damp
to keep any solid from being washed into the filter flask (the edges of the filter paper will curl up if it dries).
Precipitate will be lost if the paper is not sealed properly onto the funnel. Swirl the precipitate and
solution and quickly pour the copper(II) carbonate onto the the dampened filter paper, allowing the solution
to filter through by suction. If any precipitate is left in the beaker, add 5 mL of cold deionized water to the
beaker, swirl and pour onto the filter paper. Examine the filtrate. This liquid should be nearly colorless. If
it is not colorless, what could be the origin of the color? When all the liquid has passed through the Buchner
funnel, rinse the beaker and wash the precipitate three times with
30 mL portions of cold deionized water. Do this by adding the 30 mL portions of water to the beaker and
then pouring it over the precipitate. Is there any difference in the filtrate? Leave the vacuum connected to
the flask, and allow the copper(II) carbonate to air-dry for 10 minutes by continuing to draw air through the
precipitate. Disconnect the vacuum, take off the Buchner funnel, and discard the filtrate in the appropriate
waste container. Keep the copper(II) carbonate precipitate for Part III.
Part III. Copper(II) sulfate from Copper(II) carbonate.
Prepare a dilute H2SO
4
solution by carefully adding 5.0 mL of 6.0 M H2SO
4
to 15 mL of water in a small
beaker. (DANGER!! ALWAYS POUR ACID INTO WATER).
Carefully transfer the solid copper(II) carbonate from the filter paper into the rinsed original 150 mL beaker
(from Part II) as follows: first, use the rounded end of your stirring rod to loosen the copper(II) carbonate
precipitate from the surface of the filter paper, then. scrape the precipitate into the beaker. Put the filter
paper with any remaining copper(II) carbonate residue back into the Buchner funnel and place the funnel
inside the 150 mL beaker.
To dissolve the remaining copper(II) carbonate on the filter paper and funnel, use a Pasteur pipet to slowly
drop the dilute H2SO
4
solution onto the filter paper and sides of the funnel. Allow the liquid to drain into the
150 mL beaker. The reaction should remove nearly all of the copper(II) carbonate from the filter paper
and the funnel.
