Acid-alkali theory

Nicholas Lemery (1645-1715 CE) was a corpuscularian who favored a five-element theory (water, spirit, oil, salt, and earth). His acid/alkali theory invoked spikes on an acid that interacted with the pores of the base. In 1675 CE in Paris, he published Cours de Chymie, a textbook that was translated into English, German, Italian, Latin, and Spanish and was popular for more than fifty years. In this book, he espoused the Cartesian corpuscular mechanism (45). 

Lemery s defense of the five principles and his corpuscular account of the acid-alkali reactions (quoted above) raise the possibility that he was aware of Boyle s critique of chemists principles and of the acid-alkali theory. As a leading Protestant apothecary employed in the royal household, Lemery should have been acquainted with other Protestant chemists in Paris. He returned to Paris in 1672, soon after Du Clos s critique of Boyle caused a stir within the Academy. He also knew Wilhelm Homberg, who had worked briefly in Boyle s laboratory. " It seems quite likely that Lemery incorporated Boyle s critique of chemical principles into the French didactic tradition, creating a unique blend of chemical philosophy. His limited yet flexible use of the corpuscular imagery illustrates well the fluidity of French didactic discourse in accommodating the current philosophical fashion. 

While both Tachenius role in the acid-alkali theory and the use of this theory by Lemery have previously been recognized,15 what has not been noted is that Tachenius system, when joined with the corpuscular reasonings present in chymistry from the thirteenth-century Geber down to early seventeenth-century Daniel Sennert and others is sufficient on its own to explain the whole background to Lemery s mechanical explanations, without recourse to Descartes. 

One of Boerhaave s predecessors at the University of Leyden, a prominent participant in chemical discussions in the later seventeenth century, was Franciscus de le Boe Sylvius (1614-1672). Sylvius had practiced medicine both at Hanau and Amsterdam before joining the medical faculty at Leyden in 1658. From that position he represented both experimental anatomy and medical chemistry, and he made use of chemical explanations to describe both the nature of disease and the functions of the body. Like van Helmont before him, Sylvius gave his attention to fermentation and concluded that the process of fermentation was essential to the physiological process of digestion. Van Helmont had also suggested that the fermentation that accounted for digestion, although due ultimately to a spiritual force, was also affected by the operation of acid in the body and, indirectly, by the presence of alkali. In that muted moment, a new view of the basic components of the chemical operation of the body was born—the acid/alkali theory. What bubbled up from this theoretical mixture continued to interest chemical writers for several decades thereafter. 

It was a nice theory and, even though uncontaminated by alchemical speculation, one that would hardly last the century. Moreover, taking Lemery s mechanical interpretation of the acid/alkali theory at face value and characterizing his description of matter as a radical break from previous chemical approaches is, some have claimed, not only to undervalue the persistence of preceding alchemical ideas but to distort the extent to which the mechanical... 

Numerous measurements of the conductivity of aqueous solutions performed by the school of Friedrich Kohhansch (1840-1910) and the investigations of Jacobns van t Hoff (1852-1911 Nobel prize, 1901) on the osmotic pressure of solutions led the young Swedish physicist Svante August Arrhenius (1859-1927 Nobel prize, 1903) to establish in 1884 in his thesis the main ideas of his famous theory of electrolytic dissociation of acids, alkalis, and salts in solutions. Despite the sceptitism of some chemists, this theory was generally accepted toward the end of the centnry. 

Van Helmont, the most prominent of the seventeenth-century iatro-chemists, made the acid-alkali reaction the chemical model for a theory of animal digestion. One of his pupils, Sylvius by name, carried this idea into a total system by claiming that all bodily functions were acid-alkali reactions, and that all body fluids were either acidic or alkaline. This theory... 

Paris, becoming the outstanding chemist of the Paris Academy at the end of the seventeenth century. His work was focused on the behavior and composition of neutral salts, an investigation derived from the recently popular medical theory of acid/alkali. Earlier experience in the century had established the pattern of neutralization of an acid by an alkali, a pattern of mutual destruction of properties. The available acids were the vitriolic or spirit of sulphur, spirit of nitre, spirit of sea salt, and acid of vinegar. The only alkali was salt of tartar (potassium carbonate). Lime was known but possessed a separate identity, not clearly classed as either alkali or earth. 

It is well known that Robert Boyle was the major proponent of the apphcation of particulate or corpuscular theories to chemical phenomena in the 17th-centuiy, though neither he nor his contemporaries were able to develop a specific form of the theoiy which could be meaningfully related to quantitative chemical data. As a consequence, the trae impact of mechanical corpuscularism on 17th-centuiy chemistry was largely indirect and is best illustrated, as J. E. Marsh observed many years ago, in terms of its application to the acid-alkali theoiy of salt formation. 

Superbase — This term is used for reagents which possess an extremely strong - proton affinity. Alkali-organyls, e.g., butyl-potassium, and methyl-lithium are examples for that group. Superbases have been known since the mid-19th century however, the name has been only created following the discovery of - superacids. See also - acid-base theories. 

It is important to note that those substances (alkali hydroxides) which are, according to the classical acid-base theory, strong bases are in fact not forming uncharged molecules, but are invariably ionic in nature even in the solid state. Thus, the formula NaOH is illogical, the form Na+, OH" or Na+ + OH" would really express the composition of sodium hydroxide. The basic nature of these strong bases is due to the OH- ions which are present in the solid state or aqueous solution. 

Chemistry (Theoretical and Applied).—Air. Water. Chemical theory. Acids, alkalies and salts. Carbon and its oxides fuels. Soaps. Textile fabrics. Water softeners. Sugars, starch, alcohol, acetic acid. Proteins. Fats. Yitamines. Yeasts, moulds and bacteria. Study of certain foods. Preservation and sterilisation of food stuffs. The practical work will be partly illustrative of the lectures, and partly experimental craft work, i.e. —... 

This theory of electrolytic dissociation, or the ionic theory, attracted little attention until 1887 when vanT IIoff s classical paper on the theory of solutions was published. The latter author had shown that the ideal gas law equation, with osmotic pressure in place of gas pressure, was applicable to dilute solutions of non-electrolytes, but that electrolytic solutions showed considerable deviations. For example, the osmotic effect, as measured by depression of the freezing point or in other ways, of hydrochloric acid, alkali chlorides and hydroxides was nearly twice as great as the value to be expected from the gas law equation in some cases, e.g., barium hydroxide, and potassium sulfate and oxalate, the discrepancy was even greater. No explanation of these facts was offered by vanT Iloff, but he introduced an empirical factor i into the gas law equation for electrolytic solutions, thus... 

Taking his cue from Boyle, Boerhaave treated the chemical principles in the same way that he treated Sylvius s acid and alkali theory as theoretical speculations. Boerhaave accepted Boyle s arguments found in the Sceptical Chymist and elsewhere that asserted that the so-called principles or elements chemists claimed to isolate through their analyses were, in fact, not the primary constituents of bodies, but rather were artifacts of the chemists operations themselves. He presented this argument as a thesis in his very first chemistry course (1702) as follows ... 

Textbooks of analytical chemistry should be consulted for further details concerning the ionization of weak acids and bases and the theory of indicators, buffer solutions, and acid-alkali titrations. 

For the explanation of hydrolytic dissolution processes currently is widely used activated-complex theory, which is also called transition state theory or absolute reaction rate theory. According to this theory, at hydration and protonation on the surface of the mineral form functional groups X-OH, X-OH and X-0 , which have acid-alkali properties dependent on pH of the solution. However, not the entire specific surface of the mineral participates in dissolution reactions but only its effective portion, which is taken by the... 

Under the activated complex theory, chemical interaction of most minerals with a solution has mostly acid-alkali nature and depends on relative concentrations of complexes X-OH, X-OH and X-O" on their surface. That is why ions H " (HjO" ) and OH" are most active components in water composition, which serves as catalyst or inhibitor. Their relative role is defined by the pH value of the solution. As a rule, this correlation rate of dissolution vs. pH has a trough-like shape (Figure 2.33). At the same temperature, the slowest dissolution rate is usually observed in neutral water (pH = 7 2). As pH decreases or increases, the dissolution rate increases... 

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