Germain Henri

Propanil is one of a group of amide herbicides (made from aniline treated with organic acids), and is used extensively to control weeds in rice crops. Rice itself contains an enzyme that hydrolyzes propanil to 3,4-dichloroani-line and propionic acid, and so it is resistant to the herbicide. Weeds, lacking this enzyme, are adversely affected by it. (Mammalian liver cells also have an enzyme that causes this hydrolysis.) 

(2002). Synthesis and Chemistry of Agrochemicals, Vol. VI. Symposium Series 800. Washington, DC American Chemical Society. 

Carson, Rachel (1962). Silent Spring. Boston Houghton Mifflin. 

(1986). Dioxin, Agent Orange The Facts. New York Plenum. 

Klaassen, C. D., ed. (2001). Casarett and Doull s, 6th edition. New York McGraw-Hill. 

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Germain Henri Hess is noted today for two fundamental principles of thermochemistry the law of constant summation of heat (known simply as Hess s law) and the law of thermoneutrality. These discoveries were remarkable in that they were postulated without any supporting theoretical framework and took place in a field of study almost totally neglected by his contemporaries. Hess s law is of immense practical importance and is used to this day to determine heats of reaction when their direct measurements are difficult or impossible. 

Leicester, Henry M. (1951). Germain Henri Hess and the Foundation of Thermochemistry. Journal of Chemical Education 28 581-583. 

Germain Henri Hess developed Hess s Law in 1840 after studying the heat required or emitted from reactions composed of several steps. 

This laN was first formulated by the Swiss-Russian chemist Germain Henri Hess (180 "" 1 50), who is generally regarded as the founder of the field of thermochemistry. The law follows from the principle of conservation of energy. Thus, if reactions (a) arid (bf occur there is a net evolution of 30 fccal when 1 mol of Y is produced. We can then reconvert Y into 2A + B by the reverse of reaction (c). If the heat required to do this differed from 30 kcal, we would have obtained the starting materials with a net gain or loss of heat, which would violate the principle of conservation of energy. 

Germain Henri Hess a Swiss chemist and doctor, Germain Henri Hess (1892-1850), was bom in Geneva and... 

Hess s law A derivative of the first law of thermodynamics. It states that the total heat change for a given chemical reaction involving alternative series of steps is independent of the route taken and is sometimes known as the law of constant heat summation. The law is named for the Swiss-Russian chemist Germain Henri Hess (1802-50). 

It was in 1840 that the worlds of physics and chemistry met and began to fuse in the work of a Swiss-Russian chemist, Germain Henri Hess (1802-50). He announced the results of careful measurements he had made of the actual quantity of heat evolved in the chemical reactions, of fixed quantities of some substances. He was able to demonstrate that the quantity of heat produced (or absorbed) in going from one substance to another was the same no matter by what chemical route the change occurred. 

Germain Henri Hess (Geneva, 7 August 1802-St. Petersburg, 30 November... 

Germain Henri Hess (1802-1850). Swiss chemist. Hess was bom in Switzerland but spent most of his life in Russia. For formulating Hess s law, he is called the father of thermochemistry. 

N,ESS T, GERMAiN-HENRY M and NAAS K E (1995) First feeding of Atlantic halibut Hippoglossus hippoglossus) using different combinations of Artemia or wild zooplankton. Aquaculture 130 235-250. 

Little further thermochemical work was performed until the 1830s, when Germain Henri Hess (1802-1850) embarked upon an extensive series of experimental investigations. As a result of his work he was able to formulate in 1840 the law named after him, often known as the law of constant heat summation. This states that the total heat change in a reaction depends only on the initial and final states of the system, and is independent of the path taken. This law is a... 

Hess, Germain Henri (1802-50) Swiss-born Russian chemist who... 

Russian chemist Germain Henri Hess articulates Hess s... 

Go to a suitable site and find the answers to the next two questions about Germain Henri Hess. 

Hess was a Russian chemist and physician whose calorimetric measurements led him to formulate the law of constant heat summation, now known as Hess s law. His given name had several versions Germain Henri in French, as shown above Hermann Heinrich in German and German Iwanowitsch in Russian. 

Enthalpy, you may recall, is a state function (Section 6.3). This means that the enthalpy change for a chemical reaction is independent of the path by which the products are obtained. In 1840, the Russian chemist Germain Henri Hess, a professor at the University of St. Petersburg, discovered this result by experiment. Hess s law of... 

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