Tuesday, May 08, 2007

Nobel Laureate: Walther Hermann Nernst


The Nobel Prize in Chemistry 1920.

"in recognition of his work in thermochemistry"

Walther Hermann Nernst won the Nobel Prize in 1920 for his work in understanding the energy of reactions. The main work is summarized in the presentation speech,
Before Nernst began his actual thermochemical work in 1906, the position was as follows. Through the law of the conservation of energy, the first fundamental law of the theory of heat, it was possible on the one hand to calculate the change in the evolution of heat with the temperature. This is due to the fact that this change is equal to the difference between the specific heats of the original and the newly-formed substances, that is to say, the amount of heat required to raise their temperature from 0° to 1° C. According to van't Hoff, one could on the other hand calculate the change in chemical equilibrium, and consequently the relationship with temperature, if one knew the point of equilibrium at one given temperature as well as the heat of reaction.

The big problem, however, that of calculating the chemical affinity or the chemical equilibrium from thermochemical data, was still unsolved.

With the aid of his co-workers Nernst was able through extremely valuable experimental research to obtain a most remarkable result concerning the change in specific heats at low temperatures.

That is to say, it was shown that at relatively low temperatures specific heats begin to drop rapidly, and if extreme experimental measures such as freezing with liquid hydrogen are used to achieve temperatures approaching absolute zero, i.e. in the region of -273° C, they fall almost to zero.

This means that at these low temperatures the difference between the specific heats of various substances comes even closer to zero, and thus that the heat of reaction for solid and liquid substances practically becomes independent of temperature at very low temperatures.
Today, Nernst is known for his other contributions to thermodynamics. In biochemistry he is responsible for the Nernst equation that relates standard reduction potentials and Gibbs free energy.

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