W2003ExpA101 - page 7 of 14

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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

solution by carefully adding 6.0 mL of 6.0 M H2SO

(2 additions(pumps) of 3 mL

each) 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 I and 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

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.