Chemistry: 1920

Nernst, Walther Hermann (1864-1941), a German physical chemist, made important contributions to the study of the thermodynamics of chemical reactions. Thermodynamics is the study of various forms of energy, such as heat and work, and of the conversion of energy from one form to another.

Thermodynamics is based chiefly on two laws that describe how energy behaves in a system, which may be anything from a simple object to a complex machine. In 1906, Nernst developed a third law of thermodynamics while working on calculations to predict the efficiency of chemical reactions. For this work, he was awarded the 1920 Nobel prize in chemistry.

The third law deals with the entropy of a system-that is, the amount of disorder or randomness in the system. The law is usually stated in terms of a system consisting of a perfect crystal of a chemical element. According to the law, the entropy of such a crystal is zero if the temperature of the crystal is absolute zero (-459.67 °F, or -273.15 °C). However, the third law also indicates that absolute zero can be approached but never reached.

The third law of thermodynamics has important applications in science and industry. For example, chemists can use it as a starting point to calculate the conditions under which certain chemical reactions are possible.

Some reactions occur spontaneously, or on their own. Such reactions always result in an increase in entropy. However, one must calculate entropy changes in both the chemicals involved in the reaction and in surrounding substances that are in contact with the chemicals. One way a chemical reaction can increase the entropy of other substances is to produce heat and raise the temperature of surrounding substances.

Nernst was born in Briesen, West Prussia (now Wabrzezno, Poland). He studied physics and mathematics at the universities of Zurich, Berlin, and Graz before earning his doctorate at the University of Wurzburg in 1887. In 1889, he developed the Nernst equation, which is used in electrochemistry, a science that deals with reactions involving electric energy. In 1894, Nernst was appointed to the department of physics at the University of Gottingen. In 1905, he was appointed professor of chemistry, and later physics, at the University of Berlin. He retired in 1933.