| MHS Chemistry The Copper Cycle - Analysis |
Name: _____________________ |
| Description | Value | Units |
| Initial mass of copper | ||
| Mass of filter paper | ||
| Final mass of filter paper + copper |
ANALYSIS
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
| Cu(s) | + | H1+(aq) | + | NO31–(aq) | ---> | Cu2+(aq) | + | N2O4(g) | + | H2O(l) |
| 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.