Ashley Wilson
5 March 2018
General Chemistry Lab – Section 202
Experiment 7- Copper cycle
Purpose:
A series of reactions that convert a piece of copper metal, via several different copper- containing compounds, back into its original elemental form will be observed. Copper wire was dissolved in nitric acid. NaOH was then added to the dissolved copper solution, precipitating into Cu(OH)2. The precipitate was then placed on a hot plate and stirred until it became CuO. After sitting , the CuO was decanted twice, and H2SO4 was added. Zinc was then added to the solution to reduce Cu2+ back to its original form, and any excess Zinc was decanted. The liquid was decanted and the solid was washed with H2O to wash away any acid, and the solid was
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In this experiment zinc was added to the solution Cu(H2O)6. Bubbles started to form around the zinc. As the reaction continued,The solution changed from a light blue color to a clear solution and the zinc changed from silver to a red color. The decanting process was done again to remove any acid. It was expected for the Zinc to undergo a change but it was unexpected for the solution to change, from light blue to clear.
Zn(s) +2H+(aq) Zn2+(aq)+H2(g)
Reduction of copper Sulfate:
As more zinc was added, the color of the solution changed from a light blue to a foggy white. The zinc bubbled and changed from silver to red. After the solution stopped bubbling this meant that the reaction was then complete. Shown below is the final product.Usually during a chemical reaction it is understable for there to a noticeable change, which is why it was expected to see a foggy white color during the reaction. But it was unexpected for the reaction to take as long as it did (about 45 minutes) and for the zinc to start clumping together.
CuSO4(aq) +Zn(s) Cu(s) +ZnSO4(aq)
Washing with