Walther Nernst

Walther Nernst was a foundational figure in physical chemistry whose pioneering work bridged the disciplines of physics and chemistry. He is best known for formulating the Nernst equation, which describes the voltage of an electrochemical cell, and for his statement of the third law of thermodynamics. For his contributions to thermochemistry, Nernst was awarded the Nobel Prize in Chemistry in 1920.

Biography

Walther Hermann Nernst was born in Briesen, West Prussia, then part of the Kingdom of Prussia. He studied physics and chemistry at the University of Zurich, the University of Graz under Ludwig Boltzmann, and the University of Würzburg, where he completed his doctorate under Friedrich Kohlrausch. His academic career began at the University of Leipzig working with Wilhelm Ostwald, a key founder of physical chemistry. In 1890, he married Emma Lohmeyer, with whom he had two sons and three daughters. Nernst later held prestigious professorships at the University of Göttingen and the University of Berlin, where he succeeded the renowned Heinrich Rubens. During World War I, he served as a volunteer driver and was involved in the development of chemical weapons, a fact he later regretted. He retired in 1933 but remained in Germany during the rise of the Nazi Party, passing away at his country estate in Zibelle in 1941.

Scientific contributions

Nernst made seminal contributions across several domains of physical chemistry and physics. Early in his career, he developed the theory of electrolytic dissociation and introduced the concept of the solubility product. His work on electrochemistry led to the fundamental Nernst equation. In the field of photochemistry, he formulated the Nernst–Thomson rule, explaining the behavior of ions in different solvents. He also invented the Nernst lamp, an early incandescent lamp that used a ceramic glower, which was later supplanted by the tungsten filament. His later research focused intensely on chemical equilibrium and the behavior of matter at very low temperatures, culminating in his heat theorem, now known as the third law of thermodynamics.

Nernst equation

The Nernst equation is a fundamental relationship in electrochemistry that calculates the electrode potential of a half-cell in an electrochemical cell. It connects the reduction potential of an electrochemical reaction to the standard electrode potential, temperature, and the activities of the chemical species involved. Derived from the principles of thermodynamics, the equation is crucial for understanding galvanic cells, batteries, and biological membrane potentials. It provides the theoretical foundation for pH measurement using glass electrodes and is indispensable in fields ranging from analytical chemistry to biophysics.

Third law of thermodynamics

Nernst's heat theorem, formally established as the third law of thermodynamics, posits that the entropy change for any isothermal process approaches zero as the temperature approaches absolute zero. This implies that the entropy of a perfect crystal at absolute zero is exactly zero. This law has profound implications, providing a definitive reference point for entropy and explaining the unattainability of absolute zero. It resolved longstanding discrepancies in chemical thermodynamics predicted by the van 't Hoff equation and was a crowning achievement for which he received the Nobel Prize in Chemistry. The law's validity was later reinforced by the quantum statistical mechanics of Max Planck and Albert Einstein.

Awards and honors

In recognition of his thermochemical work, Nernst was awarded the Nobel Prize in Chemistry in 1920. His other major honors included the Bunsen Medal of the German Bunsen Society for Physical Chemistry and the Franklin Medal from the Franklin Institute. He was a member of numerous prestigious academies, including the Royal Swedish Academy of Sciences, the Prussian Academy of Sciences, and the Royal Society in London, which awarded him the Hughes Medal in 1928. The Nernst crater on the Moon and the similarly named crater on Mars are named in his honor.

Legacy

Walther Nernst's legacy is firmly embedded in the core of modern physical chemistry. The Nernst equation remains a staple in textbooks and laboratory work worldwide. His statement of the third law of thermodynamics completed the foundational laws of thermodynamics alongside the work of Rudolf Clausius and Lord Kelvin. As a teacher and mentor at Göttingen and Berlin, he influenced a generation of scientists. His innovative spirit, exemplified by inventions like the Nernst lamp, and his theoretical rigor helped to define the emerging discipline of physical chemistry in the late 19th and early 20th centuries, securing his place as one of its principal architects. Category:German chemists Category:Nobel Prize in Chemistry winners Category:1864 births Category:1941 deaths