September 26, 2012
The Copper Cycle
The Copper Cycle is a popular experiment used to determine if an element, in this instance, copper, reverts to its elemental form after a chain of reactions. This experiment is very dangerous because of the reactions between the strong acids and bases. In this experiment I performed a series of reactions starting with copper metal and nitric acid to form copper (II) nitrate. Then I reacted copper and several other solutions such as, sodium hydroxide, sulfuric acid, ammonium hydroxide, and hydrochloric acid to form precipitates. In conclusion my percent recovery of copper was 100% due to the adequate amounts of solutions and achievement of proper chemical reactions.
Equipment and Materials:
← Copper Metal (penny)
← Nitric Acid (HNO3)(aq)
← Sodium Hydroxide (NaOH)(aq)
← Sulfuric Acid (H2SO4)(aq)
← Ammonium Hydroxide (NH4OH)(aq)
← Hydrochloric Acid (HCl)(aq)
← Zinc powder
← 2 100 ml Beakers
← 250 ml Waste Beaker
← 400 ml Beaker
← Filter paper
← Plastic Dropper
← 250 ml Erlenmeyer Flask
← Plastic Funnel
← Red Litmus paper
← Steel Wool
← Glass stirring rod
← Small test tube
← Wash bottle
← Watch Glass
I. Weigh a pre-1982 penny (should be around 3 grams)
II. Measure 2mL of concentrated nitric acid, HNO3(aq), into a 100 ml beaker under a fume hood. Place penny into the beaker of nitric acid and observe the reaction. After 5 seconds remove penny with forceps and place into second beaker.
III. Add approximately 25mL of deionized water into second beaker to remove any remaining copper ion traces and place rinse into first beaker with nitric acid. Record your observations of the copper (II) nitrate, Cu(NO3)2. Dry and weigh the penny to see how much of the copper mass was removed.
IV. Pour the solution from the first beaker into a clean 250 ml beaker while inside the fume hood. Rinse the first beaker thoroughly and pour the rinse with the solution in the 250 ml beaker.
V. Add 6 drops of Sodium Hydroxide, NaOH(aq), to the 250 ml beaker until a precipitate is formed. Test the solution with litmus paper by adding small amounts of sodium hydroxide to the solution until the solution is basic. Record your observations of copper (II) hydroxide, Cu(OH)2.
VI. Place the 250 ml beaker on a hot plate and occasionally stir the mixture during heating. Heat mixture until the solution turns completely black. Additional heating will help indicate a chemical reaction has occurred. Record your observations of copper (II) oxide, CuO. Turn off hot plate and carefully remove the beaker with the forceps. Allow the mixture to cool to room temperature. While waiting for the mixture to cool prepare a suction filtration set.
VII. Once cooled, pour the mixture into the Buchner funnel to filter the precipitate. Rinse out the beaker and pour the rinse into the Buchner funnel. (Filtrate, solution that goes through the filter, should be clear) Empty the filtrate and rinse the filter flask with deionized water (while the precipitate is still in the Buchner Funnel) Replace the funnel over the cleaned filter flask.
VIII. Carefully add 6 drops of Sulfuric Acid, H2SO4(aq), and gently stir the Buhner Funnel until the precipitate is completed reacted away. Then wash the filter paper with a small amount of deionized water. Remove the Buchner Funnel and pour the filtrate into a clean 250 ml beaker. Record your observations of copper (II) sulfate, CuSO4.
IX. Add a spatula tip quantity of zinc powder to the filtrate in the 250 ml beaker under the fume hood. (Do not inhale the fumes) Add zinc powder until the solution turns clear. (reaction is complete,...