The Effect of Hydroxyl Ion Concentration (or ofpH) on the Film Potentials of Multilayers

1939 ◽  
Vol 55 (3) ◽  
pp. 320-321 ◽  
Author(s):  
William D. Harkins ◽  
Richard W. Mattoon
Keyword(s):  
Ion Concentration ◽  
Hydroxyl Ion

Zeolite Syntheses from Superalkaline Reaction Mixtures

1992 ◽  
Vol 57 (4) ◽  
pp. 788-793 ◽  
Author(s):  
Falk Fischer ◽  
Marianne Hadan ◽  
Günter Fiedrich
Keyword(s):  
Ir Spectroscopy ◽  
Crystalline Phase ◽  
Ion Concentration ◽  
Single Crystalline ◽  
Hydroxyl Ion ◽  
Type Zeolite

The synthesis of faujasite-type zeolite from superalkaline reaction mixtures are described. The contribution shows the influence of component K2O added in the system Na2O-Al2O3-SiO2-H2O with H2O/(K2O + Na2O) = 13-15. The reaction course was investigated in the range K2O/(K2O + Na2O) from about 0.07 to 0.5. Under used conditions it is quite possible to isolate faujasite-type zeolite as a single crystalline phase. By means of IR spectroscopy, low SiO2/Al2O3 ratios from 2.0 to 2.1 in the faujasite framework have been indicated. The low SiO2/Al2O3 ratios are interpreted by a higher stability of the Si-O-Al- than the Si-O-Si- bond with increasing hydroxyl ion concentration.

scholarly journals OPTIMIZATION OF TIME REACTION AND HYDROXIDE ION CONCENTRATION ON FLAVONOID SYNTHESIS FROM BENZALDEHYDE AND ITS DERIVATIVES

2010 ◽  
Vol 5 (2) ◽  
pp. 163-168 ◽  
Author(s):  
Sri Handayani ◽  
Sunarto, Sunarto, ◽  
Susila Kristianingrum
Keyword(s):  
Reaction Time ◽  
Optimum Concentration ◽  
Ion Concentration ◽  
Optimum Time ◽  
Hydroxide Ion ◽  
Synthesis Time ◽  
Flavonoid Synthesis ◽  
Hydroxyl Ion ◽  
Optimum Reaction ◽  
Time Of Reaction

The aim of this research is to determine the optimum time of reaction and concentration of hydroxide ion on chalcone, 4-methoxychalcone and 3,4-dimethoxychalcone synthesis. Chalcone and its derivatives were synthesized by dissolving KOH in ethanol followed by dropwise addition of acetophenone and benzaldehyde. Then, the mixture was stirred for several hours. Three benzaldehydes has been used, i.e : benzaldehyde, p-anysaldehyde and veratraldehyde. The time of reaction was varied for, 12, 18, 24, 30 and 36 hours. Furthermore, on the optimum reaction time for each benzaldehyde the hydroxyl ion concentration was varied from 5,7,9,11 and 13%(w/v). The results of this research suggested that the optimum time of chalchone synthesis was 12 hours, while, 4-methoxychalcone and 3,4-dimethoxychalcone were 30 hours. The optimum concentration of hydroxide ion of chalcone synthesis was 13% and for 4-methoxychalcone and 3,4-dimethoxychalcone were 11%. Keywords: Chalcone synthesis, time of reaction, hydroxide ion concentration.

THE MECHANISMS OF PERMANGANATE OXIDATION VI. THE OXIDATION OF CYANIDE ION

1960 ◽  
Vol 38 (11) ◽  
pp. 2237-2255 ◽  
Author(s):  
Ross Stewart ◽  
R. Van der Linden
Keyword(s):  
Salt Effect ◽  
Ion Concentration ◽  
Cyanide Ion ◽  
Barium Ions ◽  
Ion Concentrations ◽  
Permanganate Oxidation ◽  
Parallel Processes ◽  
Hydroxyl Ion ◽  
Kinetic Expression ◽  
Tracer Experiments

Kinetic and oxygen-18 tracer experiments have been used in an attempt to elucidate the mechanism(s) of permanganate oxidation of cyanide. From pH 12 to 14.6 the oxidation is represented by the equation,[Formula: see text]From pH 12 to 6 the reaction was found to be complex and unstoichiometric yielding cyanate, carbon dioxide, cyanide ion, and finally cyanogen at pH 9 to 6.The rate of reduction of permanganate, as followed iodometrically and spectrophotometrically, is found to be markedly dependent on the pH of the medium and reactant concentration. The rate is negligible in acid solution but rapid in basic media.At pH greater than 12 two parallel processes are indicated which have been designated as reaction A and reaction B. Reaction A appears at low reactant concentrations 0.0004 M cyanide and higher hydroxyl ion concentrations pH 13 and is represented by the kinetic expression[Formula: see text]where k2 is independent of hydroxyl ion concentration and is insensitive to the presence of manganate and barium ions. A positive salt effect is observed and labeling experiments using permanganate enriched in oxygen18 showed that the oxygen introduced into the product cyanate comes mainly from the oxidant (70%–80% oxygen-18 transferred).The existence of a second process reaction B was indicated by the changing kinetics at higher reactant concentrations and lower basicities, by the non-linear Arrhenius plots, and by the observation that only 15–25% oxygen-18 transfer from permanganate to substrate had occurred at pH 13. The rate of this latter process is approximately represented by the kinetic expression[Formula: see text]These reactions are discussed in terms of mechanism

Kinetics and mechanism of the osmium-tetroxide-catalysed oxidation of mandelate ion by hexacyanoferrate(III) ion

1968 ◽  
Vol 21 (12) ◽  
pp. 2913 ◽  
Author(s):  
NP Singh ◽  
VN Singh ◽  
MP Singh
Keyword(s):  
Benzoic Acid ◽  
Oxidation Product ◽  
Osmium Tetroxide ◽  
Reaction Rate ◽  
Zero Order ◽  
Ion Concentration ◽  
First Order ◽  
First Order Kinetics ◽  
Catalysed Oxidation ◽  
Hydroxyl Ion

The osmium-tetroxide-catalysed oxidation of mandelate ion by hexacyanoferrate(111) ion has been studied kinetically. The reaction rate has been found to be independent of hexacyanoferrate(111) ion while the order with respect to both osmium tetroxide and mandelate ion comes out to be unity. The reaction rate follows first-order kinetics at low hydroxyl ion concentration and becomes zero order at higher concentrations. The course of the reaction has been considered to proceed through the formation of an activated mandelate-OsO4, complex which decomposes in alkaline medium giving reduced osmium(V1) followed by a fast oxidation by hexacyanoferrate(111) ion. The probable course of the reactions is also described with the help of its oxidation product, benzoic acid.

Functionalizing Surface Electrical Potential of Hydroxyapatite Coatings

2016 ◽  
Vol 102 ◽  
pp. 12-17 ◽  
Author(s):  
Liene Pluduma ◽  
Edijs Freimanis ◽  
Kārlis Gross ◽  
Heli Koivuluoto ◽  
Kent Algate ◽  
...  
Keyword(s):  
Surface Potential ◽  
Electrical Potential ◽  
Biological Response ◽  
Ion Concentration ◽  
Related Gene ◽  
Kelvin Probe ◽  
Hydroxyapatite Coatings ◽  
Hydroxyl Ion ◽  
Considerable Work ◽  
Osteoblast Attachment

While considerable work has been done on chemically functionalizing hydroxyapatite, little has been done on tailoring the electrical surface potential. This has been due to limitations in the available methods to impart a surface charge. Work to date has charged conventionally manufactured hydroxyapatite exhibiting a random crystal orientation. At the outset, the microstructure has not been optimized for the highest surface potential. The aim of this work was to both orient the crystals as well as fill the structure with hydroxyl ions for further increasing the surface electrical potential. We used hydroxyapatite coatings with the same topography, but different hydroxyl ion concentration; this altered the surface potential that was measured by Kelvin probe AFM. Results indicate that a greater hydroxyl ion concentration increases the surface potential of the hydroxyapatite coating. Coatings with a higher surface potential showed improved biological response, measured as osteoblast attachment and osteoblast related gene expression.

Studies on the ionization produced by metallic salts in flames. IV. The stability of gaseous alkali hydroxides in flames

1952 ◽  
Vol 211 (1104) ◽  
pp. 58-74 ◽  
Keyword(s):  
Electron Concentration ◽  
Direct Method ◽  
Stoichiometric Composition ◽  
Heat Of Formation ◽  
Ion Concentration ◽  
Radio Waves ◽  
Kcal Mole ◽  
Hydroxyl Ion ◽  
Wide Range ◽  
Alkali Hydroxides

The electron concentration produced by the addition of alkali metal salts to a wide range of hydrogen/air flames extending to the air-rich side of stoichiometric composition has been measured by the method of attenuation of centimetric radio waves. Considerable deviations from the predicted behaviour on the basis of the known ionization potentials of the metals and the measured temperatures have been observed. The main effect noted is that for two flames of the same temperature, but on opposite sides of stoichiometric composition, the air-rich one always shows a markedly lower attenuation, an effect which is by far the most pronounced in the case of caesium. The electron concentration throughout is considerably below the predicted level. Simple statistical calculations have shown that the formation of gaseous ion pair molecules of the alkali hydroxides by combination with the hydroxyl radicals in the flame is plausible, and an analysis of the electron concentrations on this basis has shown that the results are compatible with removal of a large amount of caesium as hydroxide, but not of potassium and sodium. This agrees with the expected difference in energy of formation of caesium and potassium hydroxides, from the gaseous metal and hydroxyl, of about 5 kcal/mole. It has not proved possible to explain the whole of the deviations of the electron concentration in this way, but by incorporation of a further effect, of production of hydroxyl ions, which is independent of the metal added, a complete resolution may be obtained. The concentrations of hydroxyl ion predicted by the analysis show agreement both with the observed discrepancy with the theoretical electron concentration, and with the order of magnitude of hydroxyl ion concentration obtained earlier by an independent and more direct method (Smith & Sugden 1952). The hydroxyl radical concentrations implied by this analysis show excellent agreement with those obtained from thermodynamic calculation of the burned gas composition at equilibrium. Values for the heat of formation of gaseous potassium hydroxide and gaseous caesium hydroxide, from the gaseous metal and hydroxyl, which the data require are 87.5 ± 3 and 92.5 ± 3 kcal/mole respectively. The analysis of the results further implies an electron affinity for gaseous OH of 69 ± 5 kcal/mole, which agrees reasonably with the value obtained previously from flame measurements of 62 ± 6 kcal/mole.

The Influence of Hydroxyl Ion Concentration on the Autoxidation of Hydroquinone

1941 ◽  
Vol 63 (12) ◽  
pp. 3441-3444 ◽  
Author(s):  
John R. Green ◽  
Gerald E. K. Branch
Keyword(s):  
Ion Concentration ◽  
Hydroxyl Ion
Sign in / Sign up

Export Citation Format

Share Document