Transcript PowerPoint - Galvanic Cells Lab Answers - Half-Cell

Making Galvanic Cells Lab
No bridge
Cu – Al
0V
Cu – Zn
0V
Al – Zn
0V
Voltage Points to Deposit
2.0 V
Cu
Cu
1.1 V
Cu
Cu
0.9 V
Zn
Zn
3) The salt bridge allows the cell to continue to
function. K+ or NO3– can move into one of the
half cells to balance the charge created by +
metal ions forming or leaving solution.
4) No. We did not get the same values in the lab
Cu – Zn cell
Electron flow
Cu (+) Salt bridge
Cu2+
Zn (–)
Zn2+
Zn  Zn2+ + 2e– (oxidation - LEO)
Cu2+ + 2e–  Cu (reduction - GER)
Cu2+ +ZnCu+Zn2+
Al – Zn cell
Electron flow
Al (–)
Al3+
Salt bridge Zn (+)
Zn2+
Zn2+ + 2e–  Zn (reduction - GER)
Al  Al3+ + 3e– (oxidation - LEO)
2Al+3Zn2+  2Al3+ +3Zn
Making Galvanic Cells Lab
Cu-Zn
No bridge
voltage
0
Al-Zn
No bridge
voltage
0
0 sec
30 sec
Deposit
Points to
 0.9
 0.9
Cu
Cu
0 sec
30 sec
Deposit
Points to
 0.5
 0.5
Al
Al
3) The salt bridge allows the cell to continue to
function. K+ or NO3– can move into one of the
half cells to balance the charge created by +
metal ions forming or leaving solution.
4) No. We did not get the same values in the lab
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