Function Of Acid Concentration Research Articles

Temperature jump kinetics of the binding of imidazole to ferriprotoporphyrin IX

The kinetics of binding of imidazole to ferriprotoporphyrin IX (hemin) in aqueous ethanol has been studied at 25° using the temperature jump technique. The reaction was studied quantitatively as a function of acid concentration using the pH scale developed by Bates et al. for mixed solvent systems. The results can be explained by a mechanism in which the imidazolium ion binds to hemin with a specific rate constant of (4 ± 2) × 106 M−1 s−1 and imidazole binds with a rate constant of (3 ± 0.3) × 104 M−1 s−1. The dissociation constant for the imidazolium ion was determined by acid–base titration to be 1.8 × 10−7 M, and a dissociation constant for the hemin of 2.3 × 10−7 M was determined by spectrophotometric titration in a solvent containing 44.5 weight % of ethanol. The latter dissociation involves the proton on a solvent ligand.

Verteilungsgleichgewichte und Eigenschaften der organischen Phase im System Salzsäure — Wasser — Diisobutylcarbinol

The distribution of hydrochloric acid, water and diisobutylcarbinol (DIBC) between the aqueous and organic phase has been studied at 20°C as a function of acid concentration ranging from 0 to 12 N in the aqueous phase. The density, viscosity, electric conductivity, and dielectric constant of the organic phase have also been measured at 20°C as a function of acid concentration. The acid is extracted as an undissociated ion pair HCl(H2O)2 (DIBC)2 whose composition is derived from the distribution data. The molecular volume of the extracted species obtained from both densities and viscosities, as well as the center-to-center distance of the ion pair derived from conductivities and dielectric constants are in agreement with this formula. With increasing acid concentration, the organic phase behaves more and more like a strongly polar solvent. Hence, the dissociation constant of the acid in that phase increases by more than 20 orders of magnitude. Beyond 8 N aqueous acid, a second species of lower DIBC-content is extracted in addition to the former one.

The kinetics of hydrogen isotope exchange reactions. Part XIV. Acid-catalysed tritium exchange and its relationship to the dehydration of t-butyl alcohol

The rate of hydrogen exchange between tritium-containing aqueous perchloric acid and the C–H bond of dissolved t-butyl alcohol has been measured at 25° as a function of acid concentration. The logarithm of the rate constant is a linear function of H0 with slope –1·35. On the assumption that exchange takes place by dehydration to isobutene followed by re-addition of labelled water, the results are used to obtain the rate constant for dehydration of t-butyl alcohol in 0·5M-perchloric acid. The value found agrees with one calculated by combining the previously determined rate constant for hydration of isobutene with the equilibrium constant for the hydration reaction evaluated from thermodynamic data. This agreement supports the view that the route via olefin is the most significant mechanism of hydrogen exchange of t-butyl alcohol in moderately dilute aqueous acid at 25°.

A study of transference and solvation phenomena—VI: Hydrochloric acid in water and water-ethanol solvents

Transference and solvation phenomena for the ions of hydrochloric acid in water, 99·7 weight per cent ethanol, and water-ethanol solvents have been studied. The transference number of the cation as a function of acid concentration in water and in 99·7 weight per cent ethanol and as a function of solvent composition are presented graphically and discussed in relation to Grotthus and ordinary conduction of the hydrogen ion and in relation to relative solvation of hydrogen and chloride ions. The amount of solvent transferred from anode to cathode is also presented graphically and discussed in relation to the transference numbers of the ions.

520. The dissolution of beryllium in aqueous solutions of mineral acids and ammonium fluoride

The rates of dissolution of beryllium metal in aqueous solutions of nitric sulfuric hydrochloric and hydrofluoric acid, and of ammonium fiuoride, were measured, and the relative rates for equimolar concentrations of the acids under similar conditions were found to be HF > H/sub 2/SO/sub 4/ approx equal HCl> HNO/sub 3/. The rate varies with the source and method of fabrication of the metal. Dissolution of beryllium in nitric acid was examined in detail as a function of acid concentration, temperature, surface properties of the metal, and the presence of hydrofluoric acid. (auth)

Substituted 1,10-Phenanthroline Ferrous Complex Oxidation-Reduction Indicators Potential Determinations as a Function of Acid Concentration

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSubstituted 1,10-Phenanthroline Ferrous Complex Oxidation-Reduction Indicators Potential Determinations as a Function of Acid ConcentrationG Frederick. Smith and Frederic P. RichterCite this: Ind. Eng. Chem. Anal. Ed. 1944, 16, 9, 580–581Publication Date (Print):September 1, 1944Publication History Published online1 May 2002Published inissue 1 September 1944https://doi.org/10.1021/i560133a014RIGHTS & PERMISSIONSArticle Views208Altmetric-Citations32LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (254 KB) Get e-Alerts