Electrochemistry — Redox Reactions & Cells

Oxidation-Reduction (Redox):

OIL RIG — Oxidation Is Loss (of electrons), Reduction Is Gain

Oxidizing agent — causes oxidation of another, gets reduced itself

Reducing agent — causes reduction of another, gets oxidized itself

Galvanic (Voltaic) cell — spontaneous, generates electricity:

Anode — oxidation occurs (negative electrode)

Cathode — reduction occurs (positive electrode)

Salt bridge maintains electrical neutrality

Electrons flow from anode to cathode through external circuit

Electrolytic cell — nonspontaneous, requires electrical input:

Used in electroplating, electrolysis of water

Anode still = oxidation; Cathode = reduction

Nernst equation:

E = E° − (RT/nF)ln Q

At standard conditions (25°C): E = E° − (0.0592/n)log Q

Standard cell potential: E°cell = E°cathode − E°anode

E°cell > 0 → spontaneous (ΔG < 0)

ΔG° = −nFE° (n = moles of electrons transferred, F = Faraday's constant 96,485 C/mol)

Reference:

Wikipedia: Electrochemistry

https://en.wikipedia.org/wiki/Electrochemistry