Initian mass of copper electrode 1.3163 g Final mass of copper electrode 1.0765g
ID: 827627 • Letter: I
Question
Initian mass of copper electrode 1.3163 g
Final mass of copper electrode 1.0765g
Initial mass of key 11.0326 g
Final mass of Key 11.2829 g
Average current 0.2707 A
Time of current application 1800 sec
1. Calculate the number of coulombs of charge passed through the electrolytic cell.
2. Calculate the theoretical number of moles of copper that should have plated out onto the
brass key.
3. Calculate the actual number of moles of copper that plated out.
4. Calculate the percent yield of copper.
5. Write the oxidation and reduction half-reactions for this process.
Explanation / Answer
a) Charge = I*t
= 0.2707 * 1800
= 487.26 C
b) theoretical no of moles = (1.3163 - 1.0765) / 63.5
= 0.003776
c)actual moles = (11.2829 - 11.0326) / 63.5
= 0.003941
d) % yirld = (0.003776 / 0.003941) * 100
= 95.81%
e) Oxidation half-
Cu ---> Cu2+ + 2e-
reduction half-
Cu2+ + 2e- ---> Cu