Nernst, (Walther) Hermann (1864–1941)

German physical chemist who was awarded the Nobel Prize for Chemistry in 1920 for work on heat changes in chemical reactions. He proposed in 1906 the principle known as the Nernst heat theorem or the third law of thermodynamics: chemical changes at the temperature of absolute zero involve no change of entropy (disorder).

Nernst was born in Briesen, Prussia (now Wabreźno, Poland), and studied at Graz and Würzburg. He became professor of chemistry at Göttingen in 1894, moving to Berlin in 1905. During World War I, he was the first scientist to propose using chemical agents as a weapon.

In solution chemistry, every pH measurement depends on theories Nernst presented in the 1880s, as does the use and theory of indicators and buffer solutions.

In 1911, with British physicist Frederick Lindemann (later Lord Cherwell), Nernst constructed a special calorimeter for measuring specific heats at low temperatures.

With German chemist Fritz Haber he studied equilibria in commercially important gas reactions, such as the reversible reaction between hydrogen and carbon dioxide to form water and carbon monoxide. In 1918, Nernst investigated reactions that are initiated by light.

Having invented a substitute for the carbon filament in an electric lamp in 1897, Nernst used the money from his patent to become a pioneer motorist. Many early automobiles had difficulty climbing hills, but Nernst devised a method of injecting nitrous oxide (dinitrogen monoxide) into the cylinders when the engine got into difficulties. In the 1920s he invented a ‘Neo-Bechstein’ piano which amplified sounds produced at low amplitudes.

His Theoretische Chemie/Theoretical Chemistry (1895) became a standard textbook.