scholarly journals V.—On the Heat Developed in the Combination of Acids and Bases. Second Memoir.

1870 ◽  
Vol 26 (1) ◽  
pp. 85-95
Author(s):  
Thomas Andrews
Keyword(s):  
The State ◽  
Dilute Solution ◽  
Acid Salt ◽  
Royal Irish Academy ◽  
Basic Salt ◽  
Acids And Bases ◽  
Quantity Of Heat

In a paper communicated to the Royal Irish Academy in 1841, I gave an account of a large number of experiments on the heat disengaged when acids and bases, taken in the state of dilute solution, enter into combination, and when bases, insoluble in water, are dissolved in dilute acids. The following general conclusions or laws were deduced from those experiments:—Law 1.—The heat developed in the union of acids and bases is determined by the base and not by the acid, the same base producing, when combined with an equivalent of different acids, nearly the same quantity of heat; but different bases, different quantities.Law 2.—When a neutral is converted into an acid salt, by combining with one or more atoms of acid, no change of temperature occurs.Law 3.—When a neutral is converted into a basic salt, by combining with an additional proportion of base, the combination is accompanied with the evolution of heat.

V. On the heat disengaged during metallic substitutions

1848 ◽  
Vol 138 ◽  
pp. 91-103
Keyword(s):  
Thermal Effects ◽  
The State ◽  
The Other ◽  
Dilute Solution ◽  
Present Communication ◽  
Philosophical Magazine ◽  
Negative Element ◽  
General Law ◽  
Metallic Element ◽  
Quantity Of Heat

In the present communication I propose to give an account of some new investiga­tions on the heat disengaged in chemical actions, which may be considered a continuation of my former inquiries on the same subject. The greater number of the experiments to be detailed in this paper were made some years ago, and the con­clusion at which I arrived was briefly announced in the Philosophical Magazine for August 1844. More recently, I have taken an opportunity to repeat many of my former experiments and to add new ones on the same subject, all of which confirm the general results formerly obtained. Having originally observed that although a very limited number of bases (potash, soda, barytes and strontia) develope nearly the same quantity of heat, when a chemical equivalent of each enters into combination with an acid, yet that the greater number of bases differ most widely from one another, when so treated, while on the other hand, that different acids (taken in the state of dilute solution) produce with the same base nearly the same amount of heat, I ventured to draw the general inference that the thermal effects produced are more intimately connected with the basic, or electro-positive, than with the acid, or electro-negative element. In conformity with this view, it appeared probable that in the decomposition of solutions of neutral salts by the addition of bases or metallic bodies, the nature of the acid or electro-negative element of the compound would exercise no special influence on the result. I have already endeavoured to establish by experiment the truth of this principle in the case of basic substitutions, and, in the present memoir, I propose to extend the same general law to the other case, in which one metallic element re­places, or is substituted for another.

scholarly journals II. On the thermal changes accompanying basic substitutions

1844 ◽  
Vol 134 ◽  
pp. 21-37 ◽  
Keyword(s):  
Simple Relation ◽  
Slight Variation ◽  
Dilute Acid ◽  
Royal Irish Academy ◽  
Thermal Changes ◽  
Chemical Knowledge ◽  
Series Of Experiments ◽  
Acids And Bases ◽  
Quantity Of Heat ◽  
Acid Element

In a communication made to the Royal Irish Academy, nearly three years ago, I described a series of experiments on the heat evolved during the mutual reaction of acids and bases upon one another, from which the general conclusion was deduced, that when the influence of all extraneous circumstances is eliminated, the heat is determined by the basic and not by the acid element of the combination. Nearly at the same time an important memoir was published by M. Hess on thermo-che­mistry, in which an opposite result was arrived at, deduced however from a very limited number of experiments, and merely announced by its author, as a probable generalization, the accuracy of which could only be determined by further researches. The principle, as stated by M. Hess, is this, that different bases disengage the same quantity of heat in combining with the same acid. In the present state of chemical knowledge we cannot attempt the resolution of this problem by direct experiments on the anhydrous acids and bases, even if we adopt the hypothesis, no longer universally admitted by chemists, that the proximate constituents of neutral salts are the ordinary acids and bases. Experiments per­formed with the concentrated acids are not adapted to yield simple results, since the mere circumstance of dilution with water produces the evolution of large quantities of heat in the case of some acids, and none, or a very slight variation of temperature in the case of others. It is for this reason that when an alkaline solution is neutral­ized by the addition of an equivalent of nitric acid, the heat disengaged is very dif­ferent, according to the state of concentration of the acid; while the same circum­stance produces little or no effect, when the tartaric acid is employed. If we insti­tute a further comparison between the results, it will be found that while no simple relation exists between the temperatures obtained with different acids in a concen­trated state, there is a very close approximation to an equal development of heat when the same base is neutralized by any dilute acid.

scholarly journals On the thermal changes accompanying basic substitutions

1851 ◽  
Vol 5 ◽  
pp. 497-498
Keyword(s):  
General Principle ◽  
Dilute Solution ◽  
Specific Heats ◽  
General Law ◽  
Thermal Changes ◽  
Series Of Experiments ◽  
Acids And Bases ◽  
In The Beginning ◽  
Solid Form ◽  
Acid Element

The author gives an account of a series of experiments which he made on the heat evolved during the mutual reaction of acids and bases upon one another, from which he draws the general conclusion that when the influence of all extraneous circumstances is eliminated from the result, the change of temperature is determined by the na­ture of the base, and not by the acid element of the combination. Hence he deduces the general law that, when one base displaces another from any of its neutral combinations with an acid, the heat evolved or abstracted is always the same, whatever the acid element may be, provided the bases are the same. The base employed in the first set of experiments for displacing others was the hydrate of potash in a state of dilute solution of known strength; this was rapidly mixed, in a suitable apparatus, with an equivalent solution of the salt to be decomposed; the change of temperature which re­sulted was accurately determined, and the due corrections for the influence of the vessels and the specific heats of the solutions and of the precipitates produced, were applied. The experimental results are stated in various tables, from which it appears that the changes of temperature, referred to 1000 parts of water, were, with salts of The differences in the results of experiments with different acids, the author observes, are not greater than usually occur in chemical reactions, in consequence of the uncertainty that exists with regard to the accurate proportions of chemical equivalents. He points out various circumstances in experiments of this nature, which tend to affect the results and lead to inaccurate conclusions, if care be not taken to guard against these sources of error. One of the principal of these is the heat which is generally evolved by the separation of a base, or new compound, in a solid form: and the author discusses the influence of this change on the results deduced from his experi­ments. He considers that these experiments sufficiently establish the general principle announced in the beginning of his paper.

scholarly journals 2. On the Heat Disengaged in the Combination of Acids and Bases. Second Memoir

1872 ◽  
Vol 7 ◽  
pp. 174-175
Author(s):  
Thomas Andrews
Keyword(s):  
Royal Society ◽  
Royal Irish Academy ◽  
The Subject ◽  
Acids And Bases ◽  
In The Beginning ◽  
Royal Society Of London

In the beginning of this paper the author recapitulates the five fundamental laws of the heat of combination, which he had deduced from his previous researches, and which form the subject of several memoirs published in the Transactions of the Royal Irish Academy and of the Royal Society of London, from 1841 to 1848.

scholarly journals THE COLLOIDAL BEHAVIOR OF EDESTIN

1922 ◽  
Vol 4 (5) ◽  
pp. 597-615 ◽  
Author(s):  
David I. Hitchcock
Keyword(s):  
Salt Concentration ◽  
Potential Difference ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Acid Salt ◽  
Salt Solutions ◽  
Hydrogen Ion Concentration ◽  
Egg Albumin ◽  
Acids And Bases ◽  
Colloidal Behavior

1. It has been shown by titration experiments that the globulin edestin behaves like an amphoteric electrolyte, reacting stoichiometrically with acids and bases. 2. The potential difference developed between a solution of edestin chloride or acetate separated by a collodion membrane from an acid solution free from protein was found to be influenced by salt concentration and hydrogen ion concentration in the way predicted by Donnan's theory of membrane equilibrium. 3. The osmotic pressure of such edestin-acid salt solutions was found to be influenced by salt concentration and by hydrogen ion concentration in the same way as is the potential difference. 4. The colloidal behavior of edestin is thus completely analogous to that observed by Loeb with gelatin, casein, and egg albumin, and may be explained by Loeb's theory of colloidal behavior, which is based on the idea that proteins react stoichiometrically as amphoteric electrolytes and on Donnan's theory of membrane equilibrium.

Practical Picture Processing

1974 ◽  
Vol 32 ◽  
pp. 338-339
Author(s):  
T. A. Welton
Keyword(s):  
Radiation Damage ◽  
Coherence Length ◽  
Spatial Information ◽  
State Of The Art ◽  
Coherent Radiation ◽  
The State ◽  
Energy Spread ◽  
Electron Micrograph ◽  
Picture Processing ◽  
Molecular Skeleton

Various authors have emphasized the spatial information resident in an electron micrograph taken with adequately coherent radiation. In view of the completion of at least one such instrument, this opportunity is taken to summarize the state of the art of processing such micrographs. We use the usual symbols for the aberration coefficients, and supplement these with £ and 6 for the transverse coherence length and the fractional energy spread respectively. He also assume a weak, biologically interesting sample, with principal interest lying in the molecular skeleton remaining after obvious hydrogen loss and other radiation damage has occurred.

Computer averaging of lattice images of poly-4-methyl-pentene-1 (P4mp1): Noise created artifacts

1987 ◽  
Vol 45 ◽  
pp. 388-389
Author(s):  
P. Pradère ◽  
J.F. Revol ◽  
R. St. John Manley
Keyword(s):  
Low Dose ◽  
Polymer Concentration ◽  
Processing System ◽  
Limiting Factor ◽  
Dilute Solution ◽  
New Techniques ◽  
Dose Unit ◽  
Lattice Images ◽  
Dose Imaging ◽  
Imaging Conditions

Although radiation damage is the limiting factor in HREM of polymers, new techniques based on low dose imaging at low magnification have permitted lattice images to be obtained from very radiation sensitive polymers such as polyethylene (PE). This paper describes the computer averaging of P4MP1 lattice images. P4MP1 is even more sensitive than PE (total end point dose of 27 C m-2 as compared to 100 C m-2 for PE at 120 kV). It does, however, have the advantage of forming flat crystals from dilute solution and no change in d-spacings is observed during irradiation.Crystals of P4MP1 were grown at 60°C in xylene (polymer concentration 0.05%). Electron microscopy was performed with a Philips EM 400 T microscope equipped with a Low Dose Unit and operated at 120 kV. Imaging conditions were the same as already described elsewhere. Enlarged micrographs were digitized and processed with the Spider image processing system.

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