Chem 142 Lab 4

Weigh a sample of your unknown. Record the mass in your notebook and transfer all of the sample to a beaker. You will need to do this in duplicate, so each lab partner can weigh out a sample and follow all of the steps for the reaction.

Add water and HCl and stir with the uncovered end of the glass stirring rod to dissolve the sample completely.

Weigh the Mg turnings onto a piece of weigh paper. Add all of the Mg turnings you weighed out to the copper-containing solution.

As you continue to stir and the reaction proceeds, solid Cu will form and a dark brown solid will form on the bottom of the beaker. This solid Cu will also coat the Mg turnings, preventing them from further reaction with the copper in solution. For this reason, you need to continue stirring and gently breaking up the Mg turnings so that fresh Mg is exposed until all of the copper has precipitated (the solution will no longer be blue)..

Label and weigh two pieces of filter paper. Set up the filter with one of the labeled weigh papers and a waste beaker so that you can discard the liquid and isolate the Cu product. You will have two beakers of product and liquid, so you'll just have to filter one at a time.

Carefully filter the Cu product from your first beaker so that all of the solid Cu is trapped on the inside of the filter cone.

Rinse product with ethanol and then acetone, according to the directions in your manual. Acetone is a hazardous chemical and needs to be handled carefully and disposed of properly.

Carefully remove the filter paper for further drying. The wet paper will be quite fragile, so try not tear it as this can lead to spilling of your product.

Carefully unfold the filter paper on the watch glass.

Place the watch glass under the heat lamp to fully dry your product, making sure the lamp is not too close - your paper could char while your product is drying and negatively affect your data. Repeat the filtering process with the contents of the second beaker.