Ludwig Wilhelmy
Encyclopedia
Ludwig Ferdinand Wilhelmy (25 December 1812, Stargard in Pommern – 18 February 1864, Berlin
) was a German scientist who is usually credited with publishing the first quantitative study in chemical kinetics
.
from 1849 to 1854 before moving to Berlin.
Wilhelmy's work in chemical kinetics concerned the acid-catalyzed conversion of a sucrose
solution into a 1:1 mixture of fructose
and glucose
, a reaction that he followed with a polarimeter
. He wrote a differential equation to describe the reaction, integrated it, and used it to interpret his experimental results. Wilhelmy found that the reaction's rate was proportional to the concentrations of sucrose and of acid present. He also examined the influence of temperature on the reaction.
According to Moore, Wilhelmy received little credit from his contemporaries for his early investigations in the field of chemical kinetics. It has been speculated that the strong physical-chemical orientation of Wilhelmy's work, the new method of polarimetry
, and the fact that Wilhelmy was relatively unknown all led to this situation. Similar laboratory results were published by Jacobus Henricus van 't Hoff
and Svante Arrhenius
30 years later, with a much greater impact.
Wilhelmy is also known for the Wilhelmy plate
method for measuring surface tension
s.
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...
) was a German scientist who is usually credited with publishing the first quantitative study in chemical kinetics
Chemical kinetics
Chemical kinetics, also known as reaction kinetics, is the study of rates of chemical processes. Chemical kinetics includes investigations of how different experimental conditions can influence the speed of a chemical reaction and yield information about the reaction's mechanism and transition...
.
Scientific work
Wilhelmy studied at Heidelberg, earning a doctorate in 1846. He worked as a PrivatdozentPrivatdozent
Privatdozent or Private lecturer is a title conferred in some European university systems, especially in German-speaking countries, for someone who pursues an academic career and holds all formal qualifications to become a tenured university professor...
from 1849 to 1854 before moving to Berlin.
Wilhelmy's work in chemical kinetics concerned the acid-catalyzed conversion of a sucrose
Sucrose
Sucrose is the organic compound commonly known as table sugar and sometimes called saccharose. A white, odorless, crystalline powder with a sweet taste, it is best known for its role in human nutrition. The molecule is a disaccharide composed of glucose and fructose with the molecular formula...
solution into a 1:1 mixture of fructose
Fructose
Fructose, or fruit sugar, is a simple monosaccharide found in many plants. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into the bloodstream during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847...
and glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
, a reaction that he followed with a polarimeter
Polarimeter
A polarimeter is a scientific instrument used to measure the angle of rotation caused by passing polarized light through an optically active substance....
. He wrote a differential equation to describe the reaction, integrated it, and used it to interpret his experimental results. Wilhelmy found that the reaction's rate was proportional to the concentrations of sucrose and of acid present. He also examined the influence of temperature on the reaction.
According to Moore, Wilhelmy received little credit from his contemporaries for his early investigations in the field of chemical kinetics. It has been speculated that the strong physical-chemical orientation of Wilhelmy's work, the new method of polarimetry
Polarimetry
Polarimetry is the measurement and interpretation of the polarization of transverse waves, most notably electromagnetic waves, such as radio or light waves...
, and the fact that Wilhelmy was relatively unknown all led to this situation. Similar laboratory results were published by Jacobus Henricus van 't Hoff
Jacobus Henricus van 't Hoff
Jacobus Henricus van 't Hoff, Jr. was a Dutch physical and organic chemist and the first winner of the Nobel Prize in chemistry. He is best known for his discoveries in chemical kinetics, chemical equilibrium, osmotic pressure, and stereochemistry...
and Svante Arrhenius
Svante Arrhenius
Svante August Arrhenius was a Swedish scientist, originally a physicist, but often referred to as a chemist, and one of the founders of the science of physical chemistry...
30 years later, with a much greater impact.
Wilhelmy is also known for the Wilhelmy plate
Wilhelmy plate
A Wilhelmy plate is a thin plate that is used to measure equilibrium surface or interfacial tension at an air–liquid or liquid–liquid interface. In this method, the plate is oriented perpendicular to the interface, and the force exerted on it is measured...
method for measuring surface tension
Surface tension
Surface tension is a property of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects to run on the water surface...
s.
Further reading
External links
- Nobel lecture of Wilhelm Ostwald - describes and pays tribute to Wilhelmy's early work