Friedrich Kohlrausch (physicist)

Friedrich Wilhelm Georg Kohlrausch (October 14, 1840 – January 17, 1910) was a German physicist who made significant contributions to the knowledge of electrolyte solutions. He is renowned for his meticulous work in determining the electrolytic conductivity of solutions and for his formulation of Kohlrausch's Law of Independent Ion Migration.

Kohlrausch's Law states that the limiting molar conductivity of an electrolyte is equal to the sum of the individual contributions of the cation and anion. This principle is foundational to understanding the behavior of ions in solution and is crucial for determining the molar conductivity of weak electrolytes which do not completely dissociate.

His early work focused on elasticity and thermoelasticity. He developed methods for measuring electrical resistance and made improvements to measuring instruments like galvanometers. He invented the Wheatstone bridge variant to measure conductivity of electrolytes.

Kohlrausch held professorships at the University of Strasbourg, the University of Würzburg, and the University of Göttingen before eventually becoming president of the Physikalisch-Technische Reichsanstalt (PTR) in Berlin, a prestigious institution dedicated to precision measurement and standardization. He oversaw the PTR's development into a leading scientific institution.

His book, Leitfaden der praktischen Physik (Guide to Practical Physics), became a standard textbook for physics students for many years and influenced generations of physicists. His research significantly advanced the fields of electrochemistry and physical chemistry, providing a foundation for understanding ion transport and solution behavior.