Wilhelmy, Ludwig

Wilhelmy, Ludwig. Ueber das Gesetz, nach welchem die Einwirkung des Sauren auf den Rohrzucker stattfindet. Annalen der Physik 81, 1850, 413-... 

Ludwig Wilhelmy, Ueber das Gesetz, nach welchem die Einwirkung der Sauren auf den Rohrzucker stattfindet, Annalen derphysik 81,1850, 413-526 Alexander Williamson, Suggestions for the Dynamics of Chemistry derived from the Theory of Aetherification, Chemical Gazette 9, 1851, 294-298 and 334-339 Marcellin Berthelot, Essai d une Theorie sur la Formation des ethers, Annales de chimie 66, 1862, 110-128. 

To calculate the impact of changing reactant concentrations, temperature, or pressure on a chemical reaction rate, a reliable quantitative measure of the change in the concentration of a reactant or product chemical species versus the change in time is needed. The first quantitative reaction rate study, carried out by Ludwig Wilhelmy in 1850, illustrates this. He followed the course of the inversion of sucrose in aqueous solution... 

One of the fathers of chemical kinetics, Louis Jacques Thenard, discovered hydrogen peroxide and measured its decomposition rates. He demonstrated for the first time, that rates of chemical reactions varied with the concentrations of the reactants. In later study Ludwig Ferdinand Wilhelmy investigated the inversion of cane sugar in the presence of acids and... 

But the possibilities have always been enough to intrigue chemists, and Thenard in the early 1800s was already attempting to measure the rate of a chemical reaction. The measurements made by Ludwig Wilhelmy around 1850 were more quantitative The quantity that he measured was the ability of sugar to rotate polarized light. 

Ludwig Ferdinand Wilhelmy (1812-1864), a German physicist published in 1850 an important paper on the kinetic on the inversion of sugar with adds (Wilhelmy, 1850, Fig. 5). 

The results of the first thorough kinetic study were published in 1850 by Ludwig Ferdinand Wilhelmy (1812-1864). He investigated the hydrolysis of sucrose in the presence of acid. This reaction could be followed with ease, since the optical rotation of the solution decreased and then changed its sign as the sucrose was hydrolysed (or inverted) to glucose and fructose. Wilhelmy showed that the rate of decrease of the sucrose concentration at a particular time was equal... 

Ludwig Ferdinand Wilhelmy (1812 1864) was born in Poland but studied in Berlin and Heidelberg. He was a skilled businessman who devoted himself to chemistry and physics. 

Kinetics—the measurement and analysis of rates of reaction—also finds its origin in the early nineteenth century. We already mentioned Thenard s measurements of the rate of hydrogen peroxide decomposition, around 1818. The first systematic analysis of reaction rates is attributed to Ludwig Wilhelmy. Around 1850 he measured the rate of inversion of cane sugar in the presence of different acids, by means of a polarimeter. He noted that the rate of change in sugar concentration was proportional to the concentrations of both the sugar and the acid. To analyze the data, he set up differential equations for the reaction rate. He even proposed an empirical relation to express the influence of temperature on the rate of reaction. 

The first person to measure the rate of a chemical reaction carefully was Ludwig Wilhelmy. In 1850, he measured how fast sucrose, upon treatment with add, hydrolyzed into glucose and fmctose. This reaction occurred over several hours, and Wilhelmy was able to show how the rate depended on the initial amount of sugar present— the greater the initial amount, the faster the initial rate. Today we can measure the rates of reactions that occur in times as short as several femtoseconds (femto = 10 ). The knowledge of reaction rates is not only practically important— giving us the ability to control how fast a reaction occurs—but also theoretically important. As you will see in Section 13.6, the rate of a reaction can tell us much about how the reaction occurs on the molecular scale. 

The Wilhelmy plate method (Ludwig Ferdinand Wilhelmy [1812-1864]) can be used to measure surface or interfacial tension at an air-liquid or liquid-liquid interface. In this method, a thin plate is oriented perpendicular to the interface, and the force exerted on it is measured. The plate is often made from glass or platinum which may be roughened to ensure complete wetting. The plate is cleaned thoroughly and attached to a scale or balance via a thin metal wire. The force on the plate due to wetting is measured via a tensiometer or microbalance and used to calculate the surface tension (y) using the Wilhelmy equation ... 

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