Report Form: Electrochemistry

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Name__________________________TA_______________________

Date ________________ Lab Section___________

Note: In preparing this report you are free to use references and consult with others. However, you may not copy from other students' work (except to compile the group data set) or misrepresent your own data.

Initial mass of cathode ___________________g

Final mass of cathode ___________________g

Mass of copper plated out ___________________g

Resistor (if used for current measurement) ___________________ohms (W )

Time (min) Voltage (V) Current (A) Time (min) Voltage (V) Current (A)

5 __________ ___________ 35 __________ __________

10 __________ ___________ 40 __________ __________

15 __________ ___________ 45 __________ __________

20 __________ ___________ 50 __________ __________

25 __________ ___________ 55 __________ __________

30 __________ ___________ 60 __________ __________

Total charge through cell ______________C

Number of moles e^- through cell ______________mol

Molar mass of copper ______________g/mol

Please answer the following questions:

1. Why is it important not to touch the cleaned cathode?

2. What is the purpose of KNO₃ in this experiment?

3. How would your results for the molar mass of copper be affected if hydrogen gas were also observed at the cathode?

4. What part of this procedure limits the accuracy of the molar mass determination?

 Alchemy: Copper into gold

1. Is this reaction an oxidation-reduction reaction?

    

    

2.  Why did the penny turn "silver"?

    

    

3. Why did it turn "gold"?

    

    

4. Why did we heat the penny to turn it "gold"?