Berzelius definition

Berzelius Definition of catalysis, catalyst, catalytic force... 

A definition of catalysis similar to that given above was stated first in about 1895 by Wilhelm Ostwald, whose work on catalysis was recognized with a Nobel prize. Sixty years before, Jakob Berzelius had coined the tenn... 

In 1814, J.J. Berzelius succeeded for the first time in systematically naming chemical substances by building on the results of quantitative analyses and on the definition of the term "element by Lavoisier. In the 19th century, the number of known chemical compounds increased so rapidly that it became essential to classify them, to avoid a complete chaos of trivial names (see Section 2.2.4). 

In 1836 Jons Jakob Berzelius considered eight seemingly unrelated experimental results and concluded that there was a common thread among them. The commonality he defined as catalysis. In doing tliis, Berzelius proposed that a catalytic force was responsible for catalytic action. The concept of catalysis is today considered by most researchers to be due to Berzelius, probably because of the popularity of his annual Handbook of Chemistiywhere he published his definition of catalytic action. For the next one hundred years many referred to the phenomenon as contact catalysis or contact action, as proposed by Mitscherlich. 

In 1835 Berzelius coined the term catalysis to describe the influence of certain substances on the nature of diverse reactions, the substances themselves apparently being unchanged by the reaction. He imbued these materials with a catalytic force capable of awakening the potential for chemical reaction between species that would normally be nonreactive at a given temperature. In more modern terms the following definition is appropriate. 

Berzelius, J. (1814, 1815). Experiments to determine the definite proportions in which the elements of organic nature are combined. Annals of Philosophy 4 409-510, 5 93-101, 174-184, 260-275. 

Although Berzelius had not considered high molecular weight substances, his definition contained the necessary elements to account for the isomerism that workers would find a few years later. The concept was, thus, not challenged through the middle Nineteenth Century, and with the establishment of... 

A series of observations in which the presence of an apparently unaffected substance initiated the progress of a chemical reaction prompted the Swedish chemist Berzelius in 1835 to introduce the term catalyst , but it was only towards the end of the last century that a dear definition could be given by Ostwald, namely a catalyst is a substance which affects the rate of a chemical reaction without appearing in the final products . This is achieved through the formation of intermediate compounds between the catalyst and the molecules involved in the reaction whereby an alternative path is offered which may be passed through with higher probability, i.e. 

The term catalysis was coined by Berzelius over 150 years ago when he had noticed changes in substances when they were brought in contact with small amounts of certain species called "ferments". Many years later in 1895 Ostwald came up with the definition that we use until today A catalyst is a substance that changes the rate of a chemical reaction without itself appearing into the products. This means that according to Ostwald a catalyst can also slow down a reaction The definition used today reads as follows A catalyst is a substance which increases the rate at which a chemical reaction approaches equilibrium without becoming itself permanently involved. 

At the time of his sixty-eighth birthday, Gahn received a novel congratulatory note from Berzelius, which read "From Herr Assessor s last letter I was happy to find new support for the doctrine of definite proportions. Heir Assessor was 68 on August 19 the following day (the 20th) I became 34 now 34X2=68, from whence it follows that Herr Assessor is equal to a multiple of me by two. .." (56). 

A catalyst was defined by J. J. Berzelius in 1836 as a compound, which increases the rate of a chemical reaction, but which is not consumed by the reaction. This definition allows for the possibility that small amounts of the catalyst are lost in the reaction or that the catalytic activity is slowly lost. 

The phenomenon under consideration was studied systematically in the beginning of the 19th century. In 1815, Davy performed experiments that dealt with catalytic combustion on platinum gauzes. The term catalysis , however, was introduced by Berzelius in 1836. He first defined a catalyst (Berzelius, 1836) as a compound, which increases the rate of a chemical reaction, but which is not consumed during the reaction. This definition was later amended by Ostwald (1853-1932) in 1895 to involve the possibility that small amounts of the catalyst are lost in the reaction or that the catalytic activity is slowly decreased A catalyst is a substance that increases the rate of approach to equilibrium of a chemical reaction without being substantially consumed in the reaction. It was more than a century after Berzelius first definition that Marcel Prettre s introduced the notion of yield The catalyst is a substance that increases the rate of a chemical transformation without modifying the yield, and that is found intact among the final products of the reaction. ... 

Berzelius introduced the term catalysis as early as 1836 to explain various decomposition and transformation reactions. He later referred to the special power that some substances (catalysts) have for influencing the affinity of chemical substances. According to the Ostwald definition of catalyst (1895), it was assumed that the catalyst remained unchanged in the course of the reaction but now it is known that it is involved in chemical bonding with the reactants during the catalytic cycle. Thus, catalysis is a process in which the rate of a reaction is enhanced under... 

When iodine is dissolved in hydriodic acid or a soln. of a metallic iodide, there is much evidence of chemical combination, with the formation of a periodide. A. Baudrimont objected to the polyiodide hypothesis of the increased solubility of iodine in soln. of potassium iodide, because he found that an extraction with carbon disulphide removed the iodine from the soln. but S. M. Jorgensen showed that this solvent failed to remove the iodine from an alcoholic soln. of potassium iodide and iodine in the proportion KI I2, and an alcoholic soln. of potassium iodide decolorized a soln. of iodine in carbon disulphide. The hypothesis seemed more probable when, in 1877, G. S. Johnson isolated cubic crystals of a substance with the empirical formula KI3 by the slow evaporation of an aqueous-alcoholic soln. of iodine and potassium iodide over sulphuric acid. There is also evidence of the formation of analogous compounds with the other halides. The perhalides or poly halides—usually polyiodides—are products of the additive combination of the metal halides, or the halides of other radicles with the halogen, so. that the positive acidic radicle consists of several halogen atoms. The polyiodides have been investigated more than the other polyhalides. The additive products have often a definite physical form, and definite physical properties. J. J. Berzelius appears to have made the first polyiodide—which he called ammonium bin-iodide A. Geuther called these compounds poly-iodides and S. M. Jorgensen, super-iodides. They have been classified 1 as... 

As early as 1828 the resemblance of sulphur to selenium was recognised both by Dumas and Berzelius, and the investigations of the latter into the clicmieal behaviour of tellurium definitely placed this element in a triad with the other two. Dumas, however, observed that oxygen, although so exceptional in its properties, approaches more closely to... 

A tellurium di-iodide has been described by Berzelius as obtained when tellurium and iodine are sublimed together, but its existence as a definite compound appears doubtful.2 Damiens 3 has shown that the so-called tellurium di-iodide is a mixture of the tetra-iodide and a solid solution of tellurium with the tetra-iodide. 

Tellurium Sulphates.—By heating a mixture of powdered tellurium and concentrated sulphuric acid until a dry residue remained, Berzelius obtained a white, earthy mass, which after analysis he concluded to be a disulphate, Te02.2S03 or Te(S04)2.8 The composition of the product, however, is somewhat uncertain on heating it yields a more definite compound of composition 2Te02..S03, which can be regarded as a basic tellurium sulphate or as a pyrotelluryl sulphate. The latter compound... 

Jince the time of Berzelius, chemists have proposed structures for the amorphous, black substance known as humic acid. In the past 150 years, much experimental work has appeared on the nature of humic acid, most of it based on classical chemical and microbiological studies. Very little information about the molecular structure of humic add has resulted from these studies however. Some of the problems plaguing investigators in this field have been (a) variation in the source of humic acid, (b) variation in the definition of humic fractions of soil and coal, (c) lack of crystallinity of the samples, (d) uncertainty of molecular weight measurements, (e) variation in extraction techniques, and (f) variation in elemental composition. The little unambiguous information that exists today is based on extensive degradation of the humic acid polymer and represents only a small fraction of the total molecule. 

These definitions were essentially the same as those put forward by Berzelius. Mulder considered, however, that, besides humus substances, products from the decomposition of organic residues, such as leucine, butyric acid, valeric acid, and formic and ethanoic acids, could exist in soil. These observations are of interest because of the information that has emerged in the past half-century about growth inhibitors and stimulators from low-molecular-weight extracts from SOM and composts. 

In 1834 Faraday proposed that the reactants have to adsorb simultaneously at the surface, but he did not really explain the catalytic action. Of course, neither did Berzelius give an explanation, but he nicely generalized many results in a simple description. Later, Ostwald gave the definition that a catalyst does not influence the thermodynamic equilibrium of reactants and products but affects the rates of the chemical reactions. The conclusions of Berzelius and Faraday proved to be correct. 

---