Viscostiy of molten alkaline-earth chlorides

Toerklep, Knut; Oeye, H. A.

doi:10.1021/je00030a006

Cited by 19 publications

(6 citation statements)

References 8 publications

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“…The first uses the ratio of the cation and anion self-diffusion coefficients. For ionic liquids, based on measurements from this laboratory, this has been found to be constant for a given salt, independent of both temperature and pressure. ,− Table lists values for a number of high-temperature molten salts from the sources given in Table S1 of the Supporting Information. − Constancy is only found for KCl, KNO 3 , TlCl, PbCl 2 , and CdCl 2 . For ZnCl 2 , where ion association is known to occur, forming species such as [ZnCl 4 ] 2– bonded in a complex, labile network, − a dependence on temperature is not unexpected, but that for the self-diffusion coefficients of LiCl, NaCl, and CaCl 2 casts some doubt on the data sets for these substances.…”

Section: δ For Molten Salts and Ionic Liquidsmentioning

confidence: 99%

Can the Transport Properties of Molten Salts and Ionic Liquids Be Used To Determine Ion Association?

Harris

2016

J. Phys. Chem. B

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There have long been arguments supporting the concept of ion association in molten salts and ionic liquids, largely based on differences between the conductivity and that predicted from self-diffusion coefficients by the Nernst-Einstein equation for noninteracting ions. It is known from molecular dynamics simulations that even simple models based on charged hard spheres show such a difference due to the (anti)-correlation of ion motions. Formally this is expressed as a difference between the velocity cross-correlation coefficient of the oppositely charged ions and the mean of those for the two like-charged ions. This article examines molten salt and ionic liquid transport property data, comparing simple and model associated salts (ZnCl, PbCl, and TlCl) including weakly dissociated molecular liquids (HO, HCOOH, HSO). Analysis employing Laity resistance coefficients (r) shows that the common ion-association rationalization is flawed, consistent with recent direct measurements of the degree of ionicity in ionic liquid chlorides and with theoretical studies. However, the protic ionic liquids [PyrOMe][BF] and [DBUH][CHSO] have larger than usual NE deviation parameters (>0.5), and large negative like-ion r, analogous to those of ZnCl. Structural, spectroscopic, and theoretical studies are suggested to determine whether these are indeed genuine examples of association.

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Section: δ For Molten Salts and Ionic Liquidsmentioning

confidence: 99%

Can the Transport Properties of Molten Salts and Ionic Liquids Be Used To Determine Ion Association?

Harris

2016

J. Phys. Chem. B

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“…Table lists the data sources for the conductivity and viscosity of the high- and moderate-temperature molten salts examined, − including the recent critically examined reference correlations for the viscosity of some halides made by Tasidou et al (The Supporting Information lists the values employed.) Data sources for an intermediate-temperature molten salt (tetrabutylammonium tetrabutylborate, [NBu 4 ][BBu 4 ]); − the eutectic mixed nitrate Rb 3 Na 2 (NO 3 ) 5 ; − and three room-temperature ionic liquids, the aprotic 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][Tf 2 N]) − and the protic salts 1-methyl-2-oxopyrrolidinium tetrafluoroborate ([PyrOMe][BF 4 ]) and 1,8-diazabicyclo-[5,4,0]-undec-7-eneium methanesulfonate ([DBUH][CH 3 SO 3 ]), are also listed.…”

Section: Introductionmentioning

confidence: 99%

“…Data sources for an intermediate-temperature molten salt (tetrabutylammonium tetrabutylborate, [NBu 4 ][BBu 4 ]); − the eutectic mixed nitrate Rb 3 Na 2 (NO 3 ) 5 ; − and three room-temperature ionic liquids, the aprotic 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][Tf 2 N]) − and the protic salts 1-methyl-2-oxopyrrolidinium tetrafluoroborate ([PyrOMe][BF 4 ]) and 1,8-diazabicyclo-[5,4,0]-undec-7-eneium methanesulfonate ([DBUH][CH 3 SO 3 ]), are also listed. Table lists Walden slopes; the classification is obtained from the Angell analysis and Nernst–Einstein deviation parameters, Δ, derived from conductivity and self-diffusion data. ,− ,− …”

Section: Introductionmentioning

confidence: 99%

On the Use of the Angell–Walden Equation To Determine the “Ionicity” of Molten Salts and Ionic Liquids

Harris

2019

J. Phys. Chem. B

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In this work, the Angell analysis of Walden plots of the conductivity of ionic liquids and other electrolytes against viscosity is used to examine simple molten salts at high temperatures, a test that does not appear to have been made previously. It is found that many simple salts such as alkali metal fluorides and chlorides are predicted to be "superionic" as their Walden plots fall above the arbitrary reference line introduced by Angell, which passes through the datum point for 1 M aqueous KCl at 25 °C. This contradicts long-standing molecular dynamics evidence in the literature showing that these salts conduct simply by ion migration in an electric field. Zinc chloride is also predicted to be "ideal", whereas one would expect it to be "subionic" in Angell's terminology given that it is an associated salt. Results for certain protic ionic liquids are also contradictory. Therefore, Angell−Walden analyses of this type do not convey any useful information other than a qualitative ranking of the conductivity of similar ionic liquids at a given viscosity and their use for estimating "ionicity" is best discontinued. It cannot and should not be used for classifying the interactions in ionic liquids. Instead, it is argued that an examination of Laity resistance coefficients is more useful in any discussion of true association in molten salts and ionic liquids where known examples show negative like-ion resistance coefficients with NE deviation parameters close to unity. Such an approach could be more fruitful in understanding the transport properties of molten salts and ionic liquids rather than simple comparisons of viscosity and conductivity.

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“…The form of the torque functions D(s) for various oscillating-body viscometers are discussed in the literature (Kestin and Newell, 1957b;Newell, 1959;Azpeitia and Newell, 1959;Beckwith and Newell, 1959;Tørklep and Øye, 1982; Figure 6.2 High temperature and high pressure capillary viscometric system (Semenyuk et al, 1977b). 1: titanium viscometer; 2: high-pressure autoclave; 3: copper block; 4: cylindrical electroheater; 5: PRT; 6: separating vessel; 7: high-pressure electro-input unit; 8: removal (withdrawal); 9: electronic voltage stabilizer (Π71M); 10: auto-transformer; 11: dead-weight pressure gauge (MP-2500); 12: indicated circuit; 13: electronic oscillograph; 14: audio-frequency oscillator.…”

Section: Theoreticalmentioning

confidence: 99%

Viscosity

Abdulagatov

Assael

2008

Hydrothermal Experimental Data

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Viscostiy of molten alkaline-earth chlorides

Abstract: Precision determinations of the viscosities of four molten alkaline-earth chlorides are reported. The following equations express the results In mPa s with 0.06-0.19% standard deviation: MgCI2, = 0.17985 exp(2470.1/T);

Cited by 19 publications

References 8 publications

Can the Transport Properties of Molten Salts and Ionic Liquids Be Used To Determine Ion Association?

Can the Transport Properties of Molten Salts and Ionic Liquids Be Used To Determine Ion Association?

On the Use of the Angell–Walden Equation To Determine the “Ionicity” of Molten Salts and Ionic Liquids

Viscosity

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