salt bridge (K+) Cation flow → (Cl-) flow ←

Zn Cu

Brief Activity Series

Strong Reducing Agent.

Strong Oxidizing Agent

How many moles of Cu can be plated out of a solution containing Cu2+ ions if a 1.50 amp current is passed through for 300 s? RXN: Cu2+ + 2e- → Cu(s) Notes: 1 amp = C/s F = 9.65 x 104 c/ mole e- Find: c → moles e-s → moles Cu 1.50 c s 300 s mole e- 9.65 x 104 C 1 mole Cu 2 mole e-s = moles Cu 2.33 x 10-3

Dividing by –nF gives Rise to the Nerst Equation. Effect of Concentration on EMF A Battery going dead. ∆G = ∆Go + RT lnQ -nFE = -nFEo + RT ln Q Dividing by –nF gives Rise to the Nerst Equation.

The Nerst Equation: Q: aA + bB ↔ cC + dD n = # of e- s transferred

The Nerst Equation allows us to find voltage under nonstandard conditions Example: Determine E (voltage) for: Fe(s) + Cd2+(aq) → Fe2+(aq) + Cd(s) When [Fe2+] = 0.10 M and [Cd2+] = 1.0 M @ 298K Half RXNs: Fe(s) → Fe2+ + 2e- Eo = +0.44 V Cd2+ + 2e- → Cd(s) Eo = -0.40 V Eo = +0.04 V + Value means spontaneous

Now try: [Fe2+] = 1.0 M and [Cd2+] = 0.01 M @ 298K - Value means non spontaneous and will go in opposite direction

What does an E = 0 value mean? For: Fe(s) + Cd2+(aq) → Fe2+(aq) + Cd(s) Eo = +0.04V K = 22