Discussion
Many of the transition metals form coordination compounds or complex salts. In this experiment you will prepare a complex salt of copper and from your data determine the theoretical yield, percentage yield, and the relative error of the procedure. The formula equation for the reaction is:
Cu(SO4).5H2O + 4NH4OH ----> Cu(NH3)4SO4. H2O + 8H2O
Procedure
Crush up a crystal of copper (II) sulfate with a mortar and pestle and mass out about 2.5 to 3.0 grams of copper (II) sulfate. Return the unused, crystals to the bottle indicated by your instructor. Place the massed crystals of copper (II) sulfate in a 150 mL beaker and add 10 mL of distilled water. Warm the mixture over a low flame until all of the crystals have dissolved. If they do not dissolve add five more milliliters of distilled water. Cool the solution down to near room temperature, 30-37 °C, and carefully add about 10 mL of 15M ammonium hydroxide in the hood. CAUTION: DO NOT SPILL THE AMMONIUM HYDROXIDE ON YOU. Stir the solution for a few minutes and then add 10-12 mL of methanol.
Cover the beaker containing the crystals and set it in your drawer over night. Filter the crystals making sure to transfer all of them to the filter paper. Rinse the crystals twice with ten milliliter portions of a cold solution of 50% distilled water and 50% methanol. Dry the crystals on a piece of paper and determine their mass. Make sure the crystals are thoroughly dry before massing.
Questions
1. Determine the theoretical yield from from the amount of copper (II) sulfate used and the information given in the introduction above.
2. Determine the percentage yield of the procedure.
3. Determine the relative error involved in the procedure.
4. Discuss any possible sources of errors.
| Questions? Comments?? |
|
|