Reformation of Copper Through the Copper Cycle
Authors:
Lauren Yarborough* and Alex Farish; Chemistry 112 Section 505.
Introduction:
Copper is a very important element due to both its chemical and physical properties but has its down sides when it comes to being earth-friendly. Since copper isn’t biodegradable, it just accumulates over time. In this experiment, both my lab partner and I looked at the chemical reactions of copper as it underwent the copper cycle.
Materials and Methods:
In the first part of this experiment, we obtained 0.2497 grams of copper turnings and placed it into a 50mL beaker. We then obtained 5mL of 6 M HNO3 and placed it into the beaker with a magnetic stir bar to stir the solution throughout the experiment. As the copper was reacting with the chemical, we noticed the copper had started to slowly dissolve. As it dissolved, the reaction produced heat which made the beaker fog up and create a brownish yellow gas. In the Second step of the experiment, we added 10mL of distilled water to the beaker and added 6 M NaOH dropwise to the solution until it turned the litmus paper blue. In step three, we heated the solution until we noticed the color change from light blue to black and then let it sit until it reached room temperature. When it reached room temperature, it looked like black sand settled to the bottom of the beaker, separating from the water. In the fourth step, the liquid was decanted before adding 10mL of distilled water. We then added about 9mL of 3 M H2SO4 dropwise to the solution until the color changed from black to the light blue we saw in the beginning of the experiment and the solid that settled at the bottom had vanished. In step five, we added 5mL of distilled water to the mixture with the stir bar, mixing the solution around. Then 0.7133 grams of 20 mesh zinc was added. The reaction between the two created heat and made the copper float to the top of the solution. After waiting about 15-20 minutes, the solution was supposed to be colorless but our solution stayed light blue. We then retrieved our magnetic stir bar before decanting most of the liquid and adding 5mL of 6 M HCl to rid of any excess zinc. In the copper recovery, a vacuum apparatus was created and used to dry out the copper from the wet filter paper. We then weighed out our copper to be about 0.6807 grams without the weight of the glass and filter paper.
Results and Discussion:
In the first part of the cycle, it involves reacting copper with nitric acid to form copper nitrate, nitrogen dioxide gas, and water. The mass of the copper we used was 0.2497 grams. The unbalanced equation for this reaction is:
Cu(s) + HNO3(aq) Cu(NO3)2(aq) + NO2(g) + H2O(l)
When you balanced it, it gives you:
Cu(s) + 4HNO3(aq) Cu(NO3)2(aq) + 2NO2(g) + 2H2O(l)
The reaction types were redox reaction, gas formation, and precipitation with observations to prove this being the copper dissolved, moisture built up on the sides of the beaker, and there was a brownish yel...
