Interactions and structure in aqueous NaNO3 solutions

Caminiti, Ruggero; Licheri, G.; Paschina, G.; Piccaluga, G.; Pinna, G.

doi:10.1063/1.439694

Cited by 85 publications

(62 citation statements)

References 13 publications

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“…In almost every case tested, we found that the V0 values corresponded to n, = 4, 6, 8, or 9, as would be anticipated on geometrical grounds. For example, for Nab(aq), we calculate V: , , = 23.7, 6.5, -9.9, -17.9, and -31.2 cm3 mol-' for coordination numbers 4, 5, 6, 7, and 8 respectively; the observed value of -6.6 cm' mol-' is consistent with n, = 6, in agreement with a recent X-ray diffraction study (40). Simi--0 .…”

Section: Theoretical Interpretation Of Absol~lte Molar Volumes Of M2+supporting

confidence: 78%

The partial molar volumes of aqueous metal cations: their prediction and relation to volumes of activation for water exchange

Swaddle¹,

Mak²

1983

Can. J. Chem.

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. J. Chcm. 61, 473 (1983).Partial molar volumes V" of the Fe", ~i " , Fe3', ~r " , ~h " , and M(NH,),0HZ3' (M = Cr, Co, Rh, Ir) aqueous ions have been obtained by extrapolation from density measurements at 298.15 K on the perchlorate salt solutions containing added HCIO, where ncccssary to suppress hydrolysis or oxidation. The values for thcsc high-spin aqua-ions and others in the literature can be represented satisfactorily for ionic chargcs z = I through 4 by whcre ?:,, is thc absolute partial molar volume in cm3 mol-' of MT'(aq) rclativc to ?:,, = -5.4 cm' mol-' for H'(aq), and r-is the Shannonradius in pm of M" with coordination number n,. Volumcs of activation AV,,:Vor watcr exchange correlate inversely with V" within the series ~" ( a q ) and M ( N H~) ~O H~" (~~) at least, allowing predictions of AV,,:!: to be made from V" or the above equation. The physical origin of these correlations is considcrcd. Our interest in the precision measurement of volume properties of aqueous metal ions stems from the observation (1, 2) that volumes of activation AV,," for the exchange of coordinated water on M2+(aq), M(NH3),OH:+(aq), and possibly M3+(aq) seem to correlate inversely with the apparent molar volumes 4, or partial molal volumes at infinite dilution V0 of the respective aqueous ions within each of these series. If this observation has any general validity, the transition states volumes must be much less sensitive to the nature of M than are either AV,,* or vO, i.e., the transition states must resemble each other relatively closely within a series despite some differences in reaction mechanism which AV,," is thought to reveal (1). Furthermore, the correlations themselves would permit prediction of unknown AV,," values from known V0 data (or vice-versa). Finally, if a physically meaningful model is available for the prediction of VO, we have the prospect of predicting AV,,*, and so arguably the mechanistic predisposition of a metal aqua-ion, from basic principles and quantities.The establishment and subsequent application of such correlation and models. however. require values of V0 that are . * accurate to within 2 dm3 mol-I or better. Good modern data are available for aqueous Mn2+, Co2+, and ~i " (3-7), but for Fe2+(aq) there exist only older V0 values which range from -17.7 to -26.4 cm3 mol-' (8-10) (relative to v0 = 0 for H+(aq)), possibly because of the rapidity of aerial oxidation of Fe2+(aq) in the absence of added acid (1 1). For Fe3+(aq), the V0 value cited in Millero's comprehensive review (10) can be traced back to density data of precision no better than 1 part in 10" which implies uncertainties in the derived molar volume of at least + 2 cm3 mol-I at 0.05 mol L-I; solution densities reproducible to about 2 parts in lo6 are now routinely measurable. In any case, addition of substantial amounts of acid is necessary to suppress hydrolysis and polymerization of iron(111) (pK, -2).[I] Fe3+(aq) + H 2 0 S H+ + Feo~"(aq) S polymers Suppression of hydrolysis is also important for Rh3+(aq), -3), for which n...

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Section: Theoretical Interpretation Of Absol~lte Molar Volumes Of M2+supporting

confidence: 78%

The partial molar volumes of aqueous metal cations: their prediction and relation to volumes of activation for water exchange

Swaddle¹,

Mak²

1983

Can. J. Chem.

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“…20,21 On the other hand, Caminiti et al investigated the hydrated structure of ions in NaNO 3 solution of 5-7 mol dm 23 by using the X-Ray diffraction technique. 22 Their results show the number of water molecules in the first hydrated shell of NO hydration is only 1-3 in their reports, while it is 3-6 even in very concentrated solution. 22 Thus, the calculations above can only provide the foundational theoretical models of hydrated nitrate but can not explain the experimental phenomena quantificationally.…”

Section: Introductionmentioning

confidence: 93%

“…22 Their results show the number of water molecules in the first hydrated shell of NO hydration is only 1-3 in their reports, while it is 3-6 even in very concentrated solution. 22 Thus, the calculations above can only provide the foundational theoretical models of hydrated nitrate but can not explain the experimental phenomena quantificationally. In this article, we optimize the nitrate clusters with 1-6 hydrated water molecules to obtain their geometries, relative energies, binding energies, and vibrational frequencies and compare the results with those in experiments.…”

Section: Introductionmentioning

confidence: 93%

Ab initio investigation on the ion‐associated species and process in Mg(NO₃)₂ solution

Zhang

2010

J Comput Chem

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In the present article, two focal subjects, i.e., hydration of the NO(3)(-) and associated ion species in the Mg(NO(3))(2) solution are researched by using the ab initio method. Nitrate ions with the hydration number of 1-6 are optimized at the HF/6-31+G* level. Their relative energies, binding energies, and v(1)-NO(3)(-) frequencies are also presented. The investigation of the binding energies shows the hydration number is 3-6 in the solvent abundant environment. The associated species, including ion pairings, triple- and multiple-ion clusters, are also optimized at the same level and their v(1)-NO(3)(-) frequencies are calculated for comparing with the results in experiments. From the comparison, the new associated process via aqueous free ions → solvent-shared ion pairings → solvent-shared triple and multiple ion clusters → contact multiple ion clusters → amorphous crystal is proposed.

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“…Sequential polymerization of ionic pair results in formation of associations having n=2-4. It is to be noted that cluster structure [14], ionic pairs and ionic triplets [11] were experimentally observed in concentrated aqueous solutions of NaNO 3 . At 15-45 °C in KNO 3 solutions hydration degree of contact ion pairs seems to be higher [4]; this might be indirectly proved by empirical compositions of KNO 3 .…”

Section: →Brmentioning

confidence: 98%

“…Pseudocompounds may be represented as hydrated contact ion pairs and their associates, as was done in the case of KNO 3 solutions [4]. This conclusion is proved by computer simulation of ion coordination based on X-ray studies of concentrated aqueous salt solutions [11][12][13]. Figure 5 shows one of the possible sequential changes of composition and structure of nNaNO 3 .…”

Section: →Brmentioning

confidence: 99%

Temperature‐concentration oscillations as a result of nanoheterophase structure of concentrated aqueous solutions of salts

Kir'yanova

2010

Cryst. Res. Technol.

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Key words crystal-solution phase equilibria, saturation temperature oscillations, nanostructure of aqueous salt solutions.Detailed precision investigation of aqueous solutions of NaBr . 2Н 2 О, KBr, RbNO 3 , and K 2 SO 4 salts showed oscillations of crystal-solution phase equilibria in the temperature range of 15-45 °C. The maximum deviations from the smooth correlation between the saturation temperature and the salt concentration (up to 4% of concentration and up to 10 °C) were found to correspond to simplest salt-water ratios. Recently, similar trends were observed for NaNO 3 , KNO 3 and K 2 CrO 4 solutions. Oscillation amplitudes for saturation temperature in the investigated series decreased in the following orders: Na -(sodium systems). Increase in total content of impurities (2-4-fold) in solution results in 1.5-2-fold elevation of the oscillation amplitudes. A concept of nanoheterophase solution was suggested to account for the observed temperature-concentration oscillations. The concept is based on the original experimental data on interrelated variation of different properties of aqueous salt solutions depending on their concentrations. Characteristic features of the phase diagrams are discussed and influence of the oscillations on crystal growth is elucidated.

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Interactions and structure in aqueous NaNO3 solutions

Cited by 85 publications

References 13 publications

The partial molar volumes of aqueous metal cations: their prediction and relation to volumes of activation for water exchange

The partial molar volumes of aqueous metal cations: their prediction and relation to volumes of activation for water exchange

Ab initio investigation on the ion‐associated species and process in Mg(NO₃)₂ solution

Temperature‐concentration oscillations as a result of nanoheterophase structure of concentrated aqueous solutions of salts

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Interactions and structure in aqueous NaNO3 solutions

Cited by 85 publications

References 13 publications

The partial molar volumes of aqueous metal cations: their prediction and relation to volumes of activation for water exchange

The partial molar volumes of aqueous metal cations: their prediction and relation to volumes of activation for water exchange

Ab initio investigation on the ion‐associated species and process in Mg(NO3)2 solution

Temperature‐concentration oscillations as a result of nanoheterophase structure of concentrated aqueous solutions of salts

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Ab initio investigation on the ion‐associated species and process in Mg(NO₃)₂ solution