Coulometric-potentiometric determination of autoprotolysis constant and relative acidity scale of water

The autoprotolysis constant and relative acidity scale of water were determined by applying the coulometric-potentiometric method and a hydrogen/palladium (H2/Pd) generator anode. In the described procedure for the evaluation of autoprotolysis constant, a strong base generated coulometrically at the platinum cathode in situ in the electrolytic cell, in presence of sodium perchlorate as the supporting electrolyte, is titrated with hydrogen ions obtained by the anodic oxidation of hydrogen dissolved in palladium electrode. The titration was carried out with a glass-SCE electrode pair at 25.0?0.1?C. The value obtained pKw = 13.91 ? 0.06 is in agreement with literature data. The range of acidity scale of water is determined from the difference between the halfneutralization potentials of electrogenerated perchloric acid and that of sodium hydroxide in a sodium perchlorate medium. The halfneutralization potentials were measured using both a glass-SCE and a (H2/Pd)ind-SCE electrode pairs. A wider range of relative acidity scale of water was obtained with the glass-SCE electrode pair.

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Determination of relative acidity scales for some dipolar aprotic solvents by coulometry using a hydrogen-palladium electrode

Journal of the Serbian Chemical Society ◽

10.2298/jsc0809871d ◽

2008 ◽

Vol 73 (8-9) ◽

pp. 871-878 ◽

Cited By ~ 1

Author(s):

Radmila Dzudovic ◽

Ljiljana Jaksic

Keyword(s):

Perchloric Acid ◽

Supporting Electrolyte ◽

Sodium Perchlorate ◽

Electrode Pair ◽

Tetrabutylammonium Perchlorate ◽

Palladium Electrode ◽

The Difference ◽

Acidity Scale ◽

Relative Acidity

A coulometric-potentiometric procedure for the determination of relative acidity scales of acetone, methylethyl ketone, methyl-isobutyl ketone and propylene carbonate is described. The range of the relative acidity scale of a solvent was determined from the difference between the half-neutralization potential of perchloric acid and that of tetrabutylammonium hydroxide. The perchloric acid was generated in situ from a hydrogen-palladium electrode in presence of sodium perchlorate or tetrabutylammonium perchlorate as the supporting electrolyte. The electrode pairs glass-SCE and (H2/Pd)ind-SCE were applied for the measurement of the half-neutralization potentials of the acid and base. A wider range of relative acidity scale of the solvents was obtained with the glass-SCE electrode pair and tetrabutylammonium perchlorate as the supporting electrolyte.

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The application of hydrogen-palladium electrode for potentiometric acid-base determinations in tetrahydrofuran

Journal of the Serbian Chemical Society ◽

10.2298/jsc120927018j ◽

2013 ◽

Vol 78 (8) ◽

pp. 1203-1212

Author(s):

Anja Jokic ◽

Radmila Dzudovic ◽

Ljiljana Jaksic ◽

Snezana Nikolic-Mandic

Keyword(s):

Maleic Acid ◽

Glass Electrode ◽

Indicator Electrode ◽

Electrode Pair ◽

Acid Base ◽

Palladium Electrode ◽

The Individual ◽

Acidity Scale ◽

Relative Acidity

The application of the hydrogen-palladium electrode (H2/Pd) as the indicator electrode for the determination of relative acidity scale (Es, mV) of tetrahydrofuran (THF) and the potentiometric titrations of acids in this solvent was investigated. The relative acidity scale tetrahydrofuran was determined from the difference half-neutralization potentials of perchloric acid and tetrabutylammonium hydroxide (TBAH), which were measured by using both H2/Pd-SCE and glass-SCE electrode pairs. The experimentally obtained value of Es scale THF with a H2/Pd-SCE electrode pair was 1155 mV, and those obtained with glass-SCE electrode pair 880 mV. By using a H2/Pd indicator electrode, the individual acids (benzoic acid, palmitic acid, maleic acid, acetyl acetone, ?-naphthol) and two component acid mixtures (benzoic acid + ?-naphthol, palmitic acid + ?-naphthol, maleic acid + ?-naphthol and maleic acid + ftalic acid) were titrated with a standard solution of TBAH. In addition, sodium methylate and potassium hydroxide proved to be very suitable titrating agents for titrating of the individual acids and the acids in mixtures, respectively. The relative error of the determination of acids in mixture was less than 3%. The results are in agreement with those obtained by a conventional glass electrode. The advantages of H2/Pd electrode over a glass electrode in potentiometric acid-base determinations in tetrahydrofuran lie in the following: this electrode gives wider relative acidity scale THF, higher the potential jumps at the titration end-point and relatively fast response time; furthermore, it is very durable, simple to prepare and can be used in the titrations of small volumes.

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ChemInform Abstract: THE REDUCTION MECHANISM AT THE MERCURY ELECTRODE IN A 0.9 M SODIUM PERCHLORATE + 0.1 M PERCHLORIC ACID SUPPORTING ELECTROLYTE OF A HYDROXYTRIPHENYLMETHANE: ERIOCHROME CYANINE R

Chemischer Informationsdienst ◽

10.1002/chin.198013094 ◽

1980 ◽

Vol 11 (13) ◽

Author(s):

J. F. C. BOODTS ◽

M. SLUYTERS-REHBACH ◽

J. H. SLUYTERS

Keyword(s):

Perchloric Acid ◽

Supporting Electrolyte ◽

Mercury Electrode ◽

Sodium Perchlorate ◽

Reduction Mechanism

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Electrochemical synthesis and characterization of BaB6 from molten melt

Journal of Mining and Metallurgy Section B Metallurgy ◽

10.2298/jmmb0901101j ◽

2009 ◽

Vol 45 (1) ◽

pp. 101-109 ◽

Cited By ~ 7

Author(s):

T.P. Jose ◽

L. Sundar ◽

L.J. Berchmans ◽

A. Visuvasam ◽

S. Angappan

Keyword(s):

Molten Salt ◽

Lithium Fluoride ◽

Barium Carbonate ◽

Supporting Electrolyte ◽

Eutectic Point ◽

Graphite Crucible ◽

Electrolytic Cell ◽

Phase Identification ◽

X Ray Diffraction ◽

Micron Size

Barium hexaboride (BaB6) crystals were electrochemically synthesized using molten salt technique. Barium carbonate (BaCO3) and boron trioxide (B2O3) was used as reactants. Lithium fluoride (LiF) was used as the supporting electrolyte. The molten electrolyte consisted of 50 wt % BaCO3 and B2O3 with different stiochiometric ratios of Ba and B and 50 wt % lithium fluoride. DTA/TGA studies were made to determine the eutectic point of the melt and it was found to be around 821oC. The electrolytic cell had a high purity graphite crucible, which served as the electrolyte holding vessel and also as the anode for the electrolysis. An electro-polished molybdenum rod was employed as the cathode. The electrolysis was performed at 870?C under argon atmosphere, at current densities ranging from 0.2-0.5 A/cm2. The electrodeposited crystals were examined for the phase identification using X-ray diffraction technique. The AAS and the chemical analysis were made for the determination of chemical composition of the synthesized crystals. The purity of the crystals was also assessed using ICP-MS, XRF and EDX, which reveal that the crystals were associated with trace amount of impurities like oxygen, carbon and iron. The compound is found to be more than 99 % pure. The morphology of the crystals was examined using Scanning Electron Microscopy (SEM). From the above studies, it is concluded that the molten salt process is a simple preparative procedure for the synthesis of sub-micron size barium hexaboride crystals.

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THE RELATIVE ACID STRENGTHS OF SUBSTITUTED PICRIC ACIDS

Canadian Journal of Chemistry ◽

10.1139/v64-171 ◽

1964 ◽

Vol 42 (5) ◽

pp. 1106-1109 ◽

Cited By ~ 1

Author(s):

John W. Elder ◽

Raymond P. Mariella

Keyword(s):

Acetic Acid ◽

Inorganic Acids ◽

Aqueous Method ◽

Aqueous Conditions ◽

Acidity Scale ◽

Relative Acidity

The relative acidity of substituted picric acids has been determined using special non-aqueous titration techniques. Other organic and inorganic acids, whose acidities in water are well known, were also determined using this non-aqueous method. A correlation of the relative acidities of known acids in water with the relative acidities of these same acids, as measured under the non-aqueous conditions used, was excellent. Using this technique a single relative acidity scale was determined ranging from acids as strong as perchloric to acids as weak as acetic acid.

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Coulometric-potentiometric determination of pKA of several organic bases in propylene carbonate

Journal of the Serbian Chemical Society ◽

10.2298/jsc0806655j ◽

2008 ◽

Vol 73 (6) ◽

pp. 655-659

Author(s):

Ljiljana Jaksic ◽

Radmila Dzudovic

Keyword(s):

Propylene Carbonate ◽

Supporting Electrolyte ◽

Sodium Perchlorate ◽

Potentiometric Method ◽

Potentiometric Determination ◽

Pka Values ◽

Reference Base ◽

Organic Bases ◽

Standard Base

The pKA values of protonated triethylamine, pyridine and 2,2'-dipyridyl in propylene carbonate (PC) were determined by applying the coulometric-potentiometric method and a hydrogen/palladium generator anode (H2/Pd). The investigated and reference base were titrated to 50 % with protons electro-generated from hydrogen-saturated palladium, in the presence of sodium perchlorate as the supporting electrolyte. The half-neutralization potentials E1/2(x) and E1/2(st.) of the investigated and standard base, respectively, were measured using a glass-SCE pair. The obtained pKA values were compared with those reported in the literature.

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Hydrogen Bond Studies

Zeitschrift für Naturforschung A ◽

10.1515/zna-1977-0206 ◽

1977 ◽

Vol 32 (2) ◽

pp. 134-139 ◽

Cited By ~ 1

Author(s):

Bo Berglund ◽

Jörgen Tegenfeldt

Keyword(s):

Asymmetry Parameter ◽

Room Temperature ◽

Sodium Perchlorate ◽

Quadrupole Coupling Constant ◽

Water Molecules ◽

Coupling Constant ◽

Nmr Spectrum ◽

Quadrupole Coupling ◽

Constant E ◽

The Difference

The quadrupole splittings in the deuterium NMR spectrum from single crystals of deuterated sodium Perchlorate monohydrate, NaClO4-D2O, have been measured at 25 °C and - 55 °C. At room temperature, the 180° flip frequency of the D2O molecules is large compared to the difference between the splittings for the two deuterons. The average quadrupole coupling constant (e2 q Q/h) and asymmetry parameter η are 134.1(4) kHz and 0.621(5), respectively. At -55 °C, the electric field gradient tensors for each of the two deuterons were observed corresponding to slowly flipping water molecules, and e2 qQ/h and η for the two deuterons are 231.5(6) and 226.7(6) kHz and 0.196(4) and 0.195(5), respectively. The results indicate that the hydrogen positions in NaClO4-H2O are dynamically disordered

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Reduced Mechanism for the Oxidation of Hydrogen Sulfide

Volume 2: 29th Computers and Information in Engineering Conference, Parts A and B ◽

10.1115/detc2009-86497 ◽

2009 ◽

Cited By ~ 1

Author(s):

H. Selim ◽

A. K. Gupta ◽

M. Sassi

Keyword(s):

Hydrogen Sulfide ◽

Oil And Gas ◽

Sulfide Oxidation ◽

Harmful Effect ◽

Reaction Conditions ◽

Efficient Manner ◽

Detailed Chemistry ◽

Reduced Mechanism ◽

Oxidation Of Hydrogen ◽

The Difference

Hydrogen sulfide is one of the most common gases accompanying fuels in oil and gas refinery processes. This gas has very harmful effect on the human health and environment so that it must be removed in an effective and efficient manner before using this fuel. These problems triggered the interest to study the chemistry of hydrogen sulfide oxidation, as it is mainly treated by chemical reactions. Simplification of the reaction mechanism will enable us to understand the properties of the chemical processes that occur during the process of hydrogen sulfide treatment. Reduction strategy is carried out here in order to reduce the detailed mechanism, where the direct relation graph and error propagation methodology (DRGEP) has been used in this paper. The results obtained from the resulting reduced mechanism showed very good agreement with the detailed chemistry results under different reaction conditions. However, some discrepancies have been found for some species, especially in the hydrogen and oxygen mole fractions. The reduced mechanism is also capable of tracking the difference in chemical kinetics that takes place due to the change in reaction conditions.

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