Unit 10 - Chpt 18 - Electrochemistry

• Balance Redox equations

• HW set1: Chpt 18 - pg. 862-865 # 30, 32 - Due Tues. Apr 20

• HW set2: Chpt 18 - pg. 862-865 # 40, 44, 50, 54, 60, 65, 74 - Due Fri. Apr 23

Workbook Lesson pkt

• Lesson 13 - Formal Oxidation number assignments - with examples and homework

• Lesson 28 - Balancing Redox Reactions with examples and homework

Sect 18.2 - 18.5 (slides provided)

Galvanic Cell schematic

Oxidation occurs at anode (vowels)

Reduction occurs at cathode (consonants)

Oxidation produces electrons, so current flows from anode to cathode.

Types of cells

Standard Hydrogen cell platinum electrodemetal electrodes

Cell Potential & Nernst Equation

• Galvanic Cell Potentials - free energy

Go = -nFEo F is Faraday constant 96485 C/mol e-

n = moles of e- from balanced Redox eqn

• Concentration Cell Potentials

G = Go + RTlnQ or K if Ecell = 0

Cell Potential & Nernst Equation

G = Go + RT ln Q

-nFE = -nFEo +RT ln Q

E = Eo - RT/nF ln Q

E = Eo - 0.0592/n log Q

So E of a cell with concentrations not equal to 1 M is the std cell potential with the correction

remember to know electrons transferred in Redox

Equilibrium, K constant

E = Eo - RT/nF log Q

At equilibrium Ecell = 0 and Q = K

0 = Eo - 0.0592/n log K

log K = nEo / 0.0592

K example

• Example 18.10 pg 841

Battery - Dry Cell