Lecture 26 3/30/07

E°

F2 (g) + 2e - ↔ 2F- +2.87

Ag+ + e- ↔ Ag (s) +0.80

Cu2+ + 2e- ↔ Cu (s) +0.34

Zn2+ + 2e- ↔ Zn (s) -0.76

Quiz

1. Consider these half-reactions1. Which is the strongest oxidizing agent?

2. Will F2(g) oxidize Ag(s) to Ag+?

3. Will Zn2+ reduce Ag+ to Ag(s)?

2. Calculate the equilibrium constant for:

Ag+ (aq) + Cu (s) ⇆ Ag(s) + Cu2+ (aq)

Kln 0257.0

En

K 298at Qlnn

0257.0EE

K 298at Qlogn

0592.0EE

1.50 amps flow through a Ag+(aq) solution for 15.0 min.

What mass of Ag metal is deposited?

The anode reaction in a lead storage battery is:

Pb(s) + HSO4-(aq) PbSO4(s) + H+(aq) + 2e-

If a battery delivers 1.50 amp, and you have 454 g of Pb, how long will the battery last?

Corrosion

http://www.gordonengland.co.uk/img/corr5.gif

http://awesomegems.com/jewelry/Cleaner-Ionic-tarnish2.jpg

E°

F2 (g) + 2e - ↔ 2F- +2.87

Au3+ + 3e- ↔ Au (s) +1.50

Cl2 (g) + 2e- ↔ 2 Cl- +1.36

O2 (g) + 4 H+ + 4e- ↔ 2 H2O +1.23

Hg2+ + 2e- ↔ Hg (l) +0.85

Ag+ + e- ↔ Ag (s) +0.80

Fe3+ + e- ↔ Fe2+ +0.77

Cu 2+ + 2 e- ↔ Cu (s) +0.34

Sn4+ + 2e- ↔ Sn2+ +0.15

2H+ + 2 e- ↔ H2 (g) 0.00

Pb2+ + 2e- ↔ Pb (s) -0.13

Sn2+ + 2e- ↔ Sn (s) -0.14

Ni2+ + 2e- ↔ Ni (s) -0.26

Zn2+ + 2 e- ↔ Zn (s) -0.76

Cr2+ + 2 e- ↔ Cr (s) -0.91

Mg2+ + 2 e- ↔ Mg (s) -2.37

Na+ + e- ↔ Na (s) -2.71

Ca2+ + 2 e- ↔ Ca (s) -2.87

Li+ + e- ↔ Li (s) - 3.04

Recap

Balancing Redox reactions Electrochemical cells Batteries Standard Reduction Potential table

Corrosion Nernst equation Electrolysis

Molten aqueous

Counting electrons

www.state.sd.us/denr/DES/mining/P000106.jpg

http://www.nelpi.org/tarcreek/slides/5s.html

Acid Mine DrainageREDOX in the real world

FeS2 (pyrite) + O2 SO42- + Fe2+