Electrochemistry

Redox

Oxidation / Reduction

Potato Clock

Leo Ger

“Lose electron oxidation” Zn 2e- + Zn2+

“Gain electron reduction”2e- + Cu2+ Cu

My name is Leo. Grr-rrrr…

Rules for assigning oxidation states

Redox Reaction

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 591

Electron Flow

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 592

Ion flow keeps the charge neutral

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 592

The salt bridge contains a strong electrolyte

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 592

The porous disk allows ion flow

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 592

Schematic of a Battery

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 593

Simple Battery

Kelter, Carr, Scott, Chemistry A Wolrd of Choices 1999, page 487

Redox of a Battery

Kelter, Carr, Scott, Chemistry A Wolrd of Choices 1999, page 487

Standard Electrode Potentials

Types of Batteries

• Lead• Ni-cad• Alkaline• Rechargeable• Mercury• Lithium

One Cell of a Lead Battery

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 595

The First Battery

Alessandro Volta (1745 – 1827)

Generate electricity by putting a layer of cardboard soaked in brine between discs of copper and zinc – a voltaic cell.When he made a ‘pile’ of these cells, heincreased the amount of electricity generated. This was the first battery – a collection of cells.

Newmark, CHEMISTRY, 1993, page 46

Zinc disc

Copper disc

A Mercury Battery

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 596

A Common Dry Cell Battery

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 596

Electroplating

Cathodic Protection of an Underground Pipe

Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 598