The Copper Cycle - Analysis
|Initial mass of copper|
|Mass of filter paper|
|Final mass of filter paper + copper|
Answer each of the following questions clearly and completely. You must show your work for the questions with a * in order to get credit.
*1. Determine the mass of copper recovered.
*2. Determine the percent recovered of your original mass.
*3. Briefly explain why your percentage was or was not 100 %.
*4. How many moles of copper did you start with?
In step 2, you added nitric acid to the copper wire. The reaction was
|copper||nitric acid||copper (II)||dinitrogen tetroxide||water|
*5. Assuming all the oxygen atoms in this reaction are oxide ions (O2–), what is the charge on each nitrogen atom before the reaction?
*6. What is the charge on each nitrogen nitrogen after the reaction?
7. Was nitrogen oxidized or reduced? Explain your reasoning.
In step 9 (step 1 one on day 2), aluminum foil was added to the blue-green
copper solution until the solution was clear. The reaction was:
3Cu2+(aq) + 2Al(s) ---> 3Cu(s) + 2Al3+(aq)
*8. What were the minimum number of moles of aluminum needed to react all your copper (according to your answer to #4)?
*9. Calculate what this mass of aluminum was.
10. Was aluminum oxidized or reduced in the is reaction? Explain your reasoning.
[Copper Cycle lab][MHS