Étude physico-chimique des solutions concentrées en acide phosphorique par voie électrochimique. Propriétés acido-basiques et oxydo-réductrices

Louis, C. Nirmala; Bessière, J.

doi:10.1139/v85-151

Cited by 16 publications

(16 citation statements)

References 10 publications

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“…We take, by convention, 2.OM H3P04 with RI(H) = R i ( H ) = -0.2 [15] as standard solution. R f ( H ) is then calculated by: (9) The Table 3 regroups the average values of R i ( H ) function.…”

Section: R F ( H )mentioning

confidence: 99%

In Situ Determination of Acidity Level in Concentrated Phosphoric Acid Solutions by Potentiometric Method at Imposed Current Intensity

Hammouti

Oudda

Elmaslout

et al. 1997

Ber Bunsenges Phys Chem

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The device constituted by two past electrodes: ferrocene and orthochloranil at fixed current potentiometry, can be used as a good sensor for the in‐situ determination of phosphoric acid concentration (2.0–14.7 M). Good agreement was observed regarding the values obtained with our method and the spectrophotometric values in synthetic phosphoric media. Different factors affecting the variation of potential at imposed current such as current intensity, temperature, stirring rate of solution and H+ ion concentrations are studied. The potential variations measured by our device between ferrocene and orthochloranil electrodes have the same values as those obtained by the voltamperometric curves. A new acidity function Ri(H), which represents the determination of the H+ activity has been introduced and compared to Strehlow Ro(H) and Hammet Ho functions. A good agreement has been observed between the Ro(H) and Ri(H) functions.

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Section: R F ( H )mentioning

confidence: 99%

In Situ Determination of Acidity Level in Concentrated Phosphoric Acid Solutions by Potentiometric Method at Imposed Current Intensity

Hammouti

Oudda

Elmaslout

et al. 1997

Ber Bunsenges Phys Chem

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“…Lorsque l'on utilise le systkme quinone/hydroquinone (Q (s)/QH,(s)), la fonction R (H) est donnCe par la relation : (9,28).…”

Section: Fonction D'acidite' R(h) Des Milieux H20-h3p04-naohunclassified

“…Plusieurs auteurs (7,9) ont signal6 l'importance du facteur activitC de l'eau dans la fixation du niveau dlaciditC des milieux eau-acide.…”

Section: Introductionunclassified

Détermination par voie électrochimique des propriétés acido-basiques et oxydo-réductrices des solutions concentrées en acide phosphorique progressivement neutralisées par la soude

Bessière¹,

Aroua²

1992

Can. J. Chem.

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Acid–base properties in 7 M H3PO4 medium neutralized by soda are characterized with an R(H) acidity function and R(H2PO4−), R(HPO42−), R(PO43−) basicity functions, which respectively represent the H+ activity in these media and their ability to donate H2PO4−, HPO42−, PO43− ions. The acidity level of these media (Na/P = 0.0–1.6), changes from R(H) = −2.7 to R(H) = +7.5. The accessible potential domain for the media studied is close to 1.23 V. Activities of these solutions in water vary between 0.66 and 0.81. The ranges of electroactivity for platinum, carbon, and mercury electrodes are also determined.

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“…It has been shown recently that concentrated solutions of mineral acids (phosphoric, hydrochloric, perchloric, sulfuric) having the same water activity, are characterized by an equal value of the Ro(H) acidity function (1). By mixing these solutions, we prepare what we call iso-acidic mixtures which have the same acidity level as the constitutive solutions, whatever the proportions (2).…”

Section: Introductionmentioning

confidence: 99%

Solvation properties in iso-acidic media involving phosphoric acid

Louis¹,

Bebba²,

Bessière³

1988

Can. J. Chem.

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Concentrated solutions of mineral acids (phosphoric, hydrochloric, perchloric, sulfuric) are characterized, for an equal value of their water activity, by an equal Ro(H) acidity level (iso-acidic solutions). By mixing them, we prepare what we call iso-acidic mixtures which keep the same acidity level as the constitutive solutions whatever the proportions; their redox and solvating properties depend both on the nature and on the ratio of the constitutive solutions. Reactivity variations for ionic species: Cl-, Br-, I-, diethyldithiophosphate (LET-), S~( W~O ,~)~~-, ~i ( w 3 0 1~) 4~-, Cu2+, CU+, Pb2+, Sn2+, c d 2 + , Zn2+, Ag+, Fe3+, Fe2+, UOz2+, U4+ in the iso-acidic mixtures are characterized by their f solvation-transfer activity coefficients. Relations between f coefficient values and complexation properties are established and it is shown that phosphoric acid has comparatively weak solvating properties toward most species. The possibility for anticipating reaction changes with the iso-acidic mixture composition by using the f coefficients is demonstrated in the case of cadmium ionic flotation with diethyldithiophosphate and silver extraction with dithizone in carbon tetrachloride.C. Louu, A. BEBBA et J. BESSIBRE. Can. J. Chem. 66, 2422 (1988).On a caracttrist des solutions concentrkes d'acides mineraux (phosphorique, chlorhydrique, perchlorique, sulfurique), ayant la m&me activitk dans l'eau et le m&me niveau d'acidite Ro(H) (solutions iso-acides). En les mtlangeant, on a prtpare ce que l'on peut appeler des melanges iso-acides qui gardent le m&me niveau d'aciditt que les solutions qui les constituent quelles que soient les proportions. Leurs propriktts de solvatation et redox dependent i la fois de la nature et du rapport des solutions de depart.On a caracterist les variations de rtactivitk des espkces ioniques C1-, Br-, I-, diethyldithiophosphate (LET-), Si(W3010)44-, c u 2 + , Cu+, pb2+, ~n " , Cd2+, Zn2+, ~g + , ~e~+ , ~e~+ , uOZ2+, u'+, des melanges iso-acides en se basant sur leur coefficient d'activitt de transfert de solvatation f . On a etabli des relations entre les valeurs du coefficient f et les proprietts de complexation et on montre que de tous les acides, c'est l'acide phosphorique qui solvate moins bien la plupart des espkces. Utilisant la flottation de I'ion cadmium par le diethyldithiophosphate d'ethyle et I'extraction i l'argent avec la dithizone dans le tttrachlorure de carbone, on dCmontre qu'il est possible de se servir du coefficient f , pour prtvoir le comportement des reactions en fonction de la composition du melange iso-acide.[Traduit par la revue]

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Étude physico-chimique des solutions concentrées en acide phosphorique par voie électrochimique. Propriétés acido-basiques et oxydo-réductrices

Cited by 16 publications

References 10 publications

In Situ Determination of Acidity Level in Concentrated Phosphoric Acid Solutions by Potentiometric Method at Imposed Current Intensity

In Situ Determination of Acidity Level in Concentrated Phosphoric Acid Solutions by Potentiometric Method at Imposed Current Intensity

Détermination par voie électrochimique des propriétés acido-basiques et oxydo-réductrices des solutions concentrées en acide phosphorique progressivement neutralisées par la soude

Solvation properties in iso-acidic media involving phosphoric acid

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