Redox 5

Page 1

SHE = Standard Hydrogen Electrode

Reference Electrode (since the potential of an electrode can NOT be measured by itself) = hydrogen

The hydrogen electrode = 0V

CONDITIONS FOR 0V:

Temperature: 25˚C

Pressure: 1 atm

[H+]: 1 mol/dm3

Electrode Potential = Reduction Half Cells

Use Table 14 in IB Data Booklet

NEGATIVE Electrode Potential:

Oxidation happens at the METAL

Stronger reducing agent than H2 (g)

POSITIVE Electrode Potential:

Reduction happens at the METAL

Weaker reducing agent than H2 (g)

VS

METHOD 1: HALF STEP EQUATIONS

Steps:

Write Half Cell Equations

Flip (if necessary) to balance electrons [Therefore, E˚ x -1]

Add the cell potential together

NOTE:

Standard Electrodes ≠ Moles

Positive E˚ Cell Potential = Spontaneous

Negative E˚ Cell Potential = Non- Spontaneous

METHOD 2: FORMULA

Oxidation: Half cell with MORE reactive metal

Reduction: Half cell with LESS reactive metal

Nature of Electrode

Temperature

Concentration of Electrolyte

Ov

Over time, the voltaic cell will be dead (e.g. a dead battery)

SHE

Predicting Cell Potentials

Factors affecting Cell Potentials

Dead Cell