The Nobel Prize in Chemistry 1992

The simplest chemical reaction

Oxidation of a molecule means the removal of electrons whereas reduction means the adding of electrons. In a reaction between two compounds an electron jumps from the donor (D), which is oxidized, to the acceptor (A), which is reduced: D + A D⁺ + A^-. The simplest reaction (self-exchange reaction) is obtained if an electron leaps between two identical molecules: A^- + A A + A^-.

During the 1950's chemists gained access to radioactive(*) isotopes. Thus it became possible to study the progress of a great number of electron transfer reactions with surprising results. It seems that electrons transfer at very different rates, the difference being up to a factor of a billion from one compound to another.

When a solution containing the green manganate ion (A^-=Mn0₄^2-) is mixed with a solution containing the violet permanganate ion (A=MnO₄^-) an electron leaps from MnO₄^2- to MnO₄^-. This happens 100 000 times per second!

Contents:
Introduction » The Marcus model » The simplest chemical reaction » Oxidation of metals » Photosynthesis » Electron transfer in living matter » Gemstones » Further reading »
Based on materials from the 1992 Nobel Poster for Chemistry. Credits and references for the poster »

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The Nobel Prize in Chemistry 1992

Rudolph A. Marcus

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