1. Schedule Today (4/10): Chapter 11 Friday (4/12): Chapter 11
Should have finished reading Chapter 11
Friday (4/12): Chapter 11
Be ready with any questions
Monday (4/15): Chapter 21
Start reading Chapter 21
No office hours Monday, April 15

2. Concentration Cells
Note the electrodes.

3. Concentration Cells – Ksp
1.0M NaCl and M Ag+(aq) excess AgCl(s)

4. Clicker Question a) 0.54 V b) 0.83 V c) 0.97 V d) 1.23 V e) 1.52 VNi
M Ni2+
1.0 M HCl Ag
AgCl(s) M HCl
Determine Ɛ for this cell.
Ksp for AgCl = 1.6 x 10–10
Ni2+ + 2e–  Ni –0.23 V
Ag+ + e–  Ag V
a) 0.54 V b) 0.83 V c) 0.97 V d) 1.23 V e) 1.52 V

5. Batteries

6. Corrosion
0.44 V 0.40 V Blue from KFe[Fe(CN)6]•H2O Pink from OH– and phenolphthalein

7. Prevention of Corrosion
Find a metal more reactive than Fe (a “sacrificial metal”). Fe  Fe2+ + 2e– (0.44 V) Mg  Mg2+ + 2e– (2.37 V) Zn  Zn2+ + 2e– (0.76 V)

8. Galvanic vs. Electrolytic
Naturally occurs to reduce Cu2+ and oxidize Zn. But what if we want to form Zn? Zn2+ + 2e–  Zn (–0.76 V) Cu2+ + 2e–  Cu (0.34 V)

9. Electroplating
Get silver metal from dissolved silver ions. To reduce silver ions, an oxidation must occur. Ag+ + e–  Ag (0.80 V)