Acid dissociation constants and rates as studied by ultrasonic absorption

Green, Larry W.; Kruus, Peeter; McGuire, Michael J.

doi:10.1139/v76-449

Cited by 18 publications

(16 citation statements)

References 17 publications

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“…However, we found only one study in which the proton dissociation rate of H 3 PO 4 was reported, with a value of k f,1 = 3.8 × 10 8 s −1 measured via ultrasonic absorption. 66 We used this value to determine the corresponding protonation rate constant k r,1 via the equilibrium constant K = k f /k r , the values for which are readily available in the literature (see the Supporting Information, Table S5). Thus, we were left with two unknown protonation/ deprotonation rate constants: one for H 2 PO 4 − and another for HPO 4 2− .…”

Section: ■ Discussionmentioning

confidence: 99%

Modeling Faradaic Reactions and Electrokinetic Phenomena at a Nanochannel-Confined Bipolar Electrode

et al. 2019

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We present the most comprehensive two-dimensional numerical model to date for a nanoconfined bipolar electrochemical system. By accounting for the compact Stern layer and resolving the diffuse part of the electrical double layer at the bipolar electrode (BPE) surface and channel walls, our model captures the impact of surface polarization and ionic chargescreening effects on the heterogeneous charge-transfer kinetics, as well as nonlinear electrokinetic transport phenomena such as induced-charge electroosmosis and concentration polarization. We employ the Poisson− Nernst−Planck and Stokes flow system of equations, unified with generalized Frumkin−Butler−Volmer reaction kinetics, to describe water electrolysis reactions and the resulting transport of ions and dissolved gases in the confined BPE system. Our results demonstrate that under a sufficiently large applied electric field, the rapid reaction kinetics on our Pt BPE dynamically transition from charge-transfer-limited to mass-transfer-limited temporal regimes as regions depleted of redox species form and propagate outward from the respective BPE poles. This phenomenon was visualized experimentally with a pH-sensitive fluorescein dye and showed excellent phenomenological agreement with our numerical calculations, providing a foundation for further understanding and developing bipolar electrochemical processes in confined geometries. We introduce two prospective applications arising from our work: (1) a hybrid hydrodynamic/electrochemical peristaltic pump and (2) deducing information about chemical kinetics through simulation.

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Section: ■ Discussionmentioning

confidence: 99%

Modeling Faradaic Reactions and Electrokinetic Phenomena at a Nanochannel-Confined Bipolar Electrode

et al. 2019

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“…present. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] The first dissociation equilibrium of the phosphoric acid:…”

Section: Introductionmentioning

confidence: 99%

Raman- and infrared-spectroscopic investigations of dilute aqueous phosphoric acid solutions

Rudolph

2010

Dalton Trans.

100

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Phosphoric acid in water and heavy water has been studied by Raman and infrared spectroscopy over a broad concentration range (0.00873-1.560 mol kg(-1)) at 23 °C. The vibrational modes of the PO(4) skeleton (C(3v) symmetry) of H(3)PO(4)(aq) and D(3)PO(4)(D(2)O) have been assigned. In addition to the P-O stretching modes a deformation mode has been detected, δPO-H(D) at 1250 and 935 cm(-1), respectively. In addition to the modes of the phosphoric acid and heavy phosphoric acid a mode of the dissociation product H(2)PO(4)(-) and D(2)PO(4)(-) has been detected at 1077 cm(-1) and 1084 cm(-1) respectively. H(3)PO(4) and D(3)PO(4) is hydrated in aqueous solution which could be verified by Raman spectroscopy following the νP[double bond, length as m-dash]O and ν(s)P(OH)(3) mode as a function of temperature. These modes show a pronounced temperature dependence inasmuch as νP[double bond, length as m-dash]O shifts to higher wavenumbers with temperature increase and ν(s)P(OH)(3) to lower wavenumbers. In the range between 300-600 cm(-1) the deformation modes have been observed. In very dilute H(3)PO(4) solutions however, the dissociation product is the dominant species. The dissociation degree, α for H(3)PO(4)(aq) and D(3)PO(4)(D(2)O) as a function of dilution has been measured at 23 °C. In these dilute H(3)PO(4)(aq) and D(3)PO(4)(D(2)O) solutions no spectroscopic features for a dimeric species of the formula H(6)P(2)O(8) and D(6)P(2)O(8) could be detected. Quantitative Raman measurements have been carried out to follow the dissociation of H(3)PO(4) and D(3)PO(4) over a very broad concentration range and also as a function of temperature. From the dissociation data, the pK(1) value for H(3)PO(4) has been determined to 2.14(1) and for D(3)PO(4) to 2.42(1) at 23 °C. In the temperature interval from 24.5 to 99.7 °C the pK(1) values for H(3)PO(4)(aq) have been determined and thermodynamic data have been derived.

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“…7 used in the analysis. It is of interest to note that y, varies relatively little with the value of Kt, due to counterbalancing effects in [5]. The p used and they, calculated here do not assume complete dissociation as some listings do.…”

Section: Correlation Of Ultrasonic and Conductivity Resultsmentioning

confidence: 94%

“…Next the degree of dissociation cr can be obtained, and hence the ionic strength p = crc for a 1 : 1 electrolyte. They, is next calculated from [5] and a new value Kc = y k 2 K,, is obtained. This iteration is continued until Kc is constant to within 0.1%.…”

Section: Correlation Of Ultrasonic and Conductivity Resultsmentioning

confidence: 99%

Ion association in solutions of HCl in DMSO–water mixtures: ultrasonic absorption studies

Kruus¹,

McGuire²

1978

Can. J. Chem.

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PEETER KRUUS and M. JACQUELINE MCGUIRE. Can. J. Chem. 56, 1881Chem. 56, (1978. Ultrasonic absorption measurements are reported for the system HCI -dimethylsulfoxide (DMSO) -water in the frequency range 3.5 to 140 MHz. For all solutions studied, the excess absorption due to the presence of HCI can be fitted well with a single relaxation equation. For 0.10 mol e -I solutions of HCI in DMSO-water mixtures, no further relaxations at higher frequencies are likely. Reasonable results are obtained when the ultrasonic results are analyzed assuming the process responsible for the excess absorption to be the dissociation-association equilibrium of HCI, and using equilibrium constants determined from conductivity (C. Cooke et 01. Electrochim. Acta, 20, 591 (1975)). The value of /AV,,,I is 20-25 cm3 mol-I and k,,, is approximately 3 x lo9 e mol-' s-I, as compared to a value of 10 x lo9 ! mol-' s-' calculated from limiting conductivities assuming diffusion-controlled rate theory.PEETER KRUUS et M. JACQUELINE MCGUIRE. Can. J. Cheni. 56, 1881Cheni. 56, (1978. On rapporte des niesures d'absorption d'ultrasons par le systeme HCI -dimethylsulfoxyde (DMSO) -eau a des frequences allant de 3.5 a 140 MHz. Pour toutes les solutions etudiees, I'absorption en exces due a la presence de HCI peut &tre bien expriniee par une seule equation de relaxation. Pour des solutions de 0.10 mol P -' de HCI dans des niClanges de DMSO -H 2 0 , il ne semble pas y avoir d'autres relaxations a des frtquences plus elevees. On obtient des resultats raisonnables lorsqu'on analyse les resultats d'ultrasons en faisant I'hypothtse que le processus responsable pour I'absorption en excts est dfi a I'equilibre association/dissociation de HCI et en faisant appel aux constantes d'kquilibre dkterminees par laconductivite(C.Cooke et 01. Electl'ochini. Acta, 20, 591 (1975)). La valeur de IAVCrrl est 20-25 cm3 mol-I et lc,,, est environ 3 x 10" P O I -I s-I ; on doit comparer cette valeur a celle de 10 x lo9 P mol-I s-', calculke a partir des conductivitCs limites en faisant appel a la thkorie de la vitesse contralee par la diffusion.[Traduit par le journal]

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Acid dissociation constants and rates as studied by ultrasonic absorption

Cited by 18 publications

References 17 publications

Modeling Faradaic Reactions and Electrokinetic Phenomena at a Nanochannel-Confined Bipolar Electrode

Modeling Faradaic Reactions and Electrokinetic Phenomena at a Nanochannel-Confined Bipolar Electrode

Raman- and infrared-spectroscopic investigations of dilute aqueous phosphoric acid solutions

Ion association in solutions of HCl in DMSO–water mixtures: ultrasonic absorption studies

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