An Infrared Study of Monosulfatopentaaquochromium(III) Chloride

Finholt, James E.; Anderson, Roger W.; Fyfe, James A.; Caulton, Kenneth G.

doi:10.1021/ic50023a009

Cited by 39 publications

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“…3 X 10~3 M and I = 1.00 M; ionic strength was maintained with lithium perchlorate to be 1.00 M at 25°. 6 The hydrogen ion concentration was corrected for the expansion of the solution with increasing temperature. = The [Cr-S04+] of the first point in these experiments was corrected using eq 3. d In these experiments [CrS04+]o = 1.5 X 10-3 M.…”

Section: Resultsmentioning

confidence: 99%

The rate of aquation of sulfatopentaaquochromium (III) ion in acidic, aqueous solution

Finholt¹,

Deming²

1967

Inorg. Chem.

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Section: Resultsmentioning

confidence: 99%

The rate of aquation of sulfatopentaaquochromium (III) ion in acidic, aqueous solution

Finholt¹,

Deming²

1967

Inorg. Chem.

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“…Figure 7 shows some proposed structural units of contact pairs of SO 4 2and Mg 2+ to form monodentate, bidentate, and bridgebidentate complexes, which have been observed in some sulfate crystals. [38][39][40][41][42] The formation of a chain structure of the contact ion pairs can explain the reduction in the evaporation rate in concentrated MgSO 4 droplets observed by Chan et al. 7 A proposed chain structure of MgSO 4 based on the structural unit of bidentate is shown in Figure 7.…”

Section: Discussionmentioning

confidence: 99%

Study of Contact Ion Pairs of Supersaturated Magnesium Sulfate Solutions Using Raman Scattering of Levitated Single Droplets

2000

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Significant retardation of the evaporation rate of levitated aqueous MgSO4 droplets has been found at high concentrations using an electrodynamic balance. Raman spectroscopy was used to study the structural changes, in particular, the formation of contact ion pairs, in supersaturated aqueous MgSO4 droplets at ambient temperatures. As the relative humidity (RH) decreases, single levitated droplets lose water and become supersaturated. A molar water-to-solute ratio as low as 1.54 was obtained, facilitating the study of contact ion pairs of unhydrated Mg2+ and SO4 2- ions in MgSO4 solutions. The characteristics of the ν1-SO4 2- band change as a function of the water-to-solute ratio. Overall, a frequency shift from 983 to 1007 cm-1 and an increase of the full width at half-height from 12 to 54 cm-1 of the ν1-SO4 2- band were observed when the water-to-solute molar ratio decreased from 17.29 to 1.54. Most of the changes occur at a ratio smaller than 6, instead of at the saturation ratio of 15.60. These changes are attributed to the formation of contact ion pairs with different structures. A chain structure based on the contact ion pair of bidentate was proposed. Formation of close contact ion pairs and chain structures can explain the retardation of evaporation of supersaturated MgSO4 droplets observed in previous experiments. On the basis of the comparisons of the Raman spectra of MgSO4 and (NH4)2SO4, we assigned the shoulder appearing at 995 cm-1 in bulk MgSO4 studies to the contact ion pairs instead of the solvent-separated ion pairs.

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“…20,21 Sulfate has been found to be coordinated with metal ions in the form of monodentate, bidentate as well as bridge-bidentate forms in solid sulfate salts, as shown in Chart 1. [22][23][24][25][26] Spectroscopic techniques, including Raman scattering, infrared spectroscopy, and NMR, provide information about contact ion pairs on a molecular level. [27][28][29][30][31][32][33][34][35][36] However, most of the studies are limited to diluted concentrations because of the constraints of saturation in bulk samples.…”

Section: Introductionmentioning

confidence: 99%

“…The formation of contact ion pairs in aqueous sulfate salt solutions has been associated to the crystal growth of double sulfate salts, such as LiASO 4 (A = Na, K, Rh, Ag, etc. ), which have applications in ionic conductors and ferroelectric materials. − Classical experimental methods such as freezing point measurements, potentiometric measurements, ultrasonic absorption, and solubility measurements, which measure the macrophysical bulk properties of solutions in which the contact ion pairs may exist, cannot yield direct information about contact ion pairs at the molecular level. − Although there are many studies on the equilibrium distributions of free ions, outer sphere ion pairs, outer−inner ion pairs and contact ion pairs in salt solutions in the literature, there has not yet been an agreement on the association constants of sulfate salts such as MgSO 4 , ZnSO 4 and CdSO 4 , especially those at higher concentrations. , Sulfate has been found to be coordinated with metal ions in the form of monodentate, bidentate as well as bridge-bidentate forms in solid sulfate salts, as shown in Chart . − Spectroscopic techniques, including Raman scattering, infrared spectroscopy, and NMR, provide information about contact ion pairs on a molecular level. − However, most of the studies are limited to diluted concentrations because of the constraints of saturation in bulk samples. By using an electrodynamic balance in which single supersaturated droplets were levitated in an electric field, we found that both monodentate and dibentate exist in supersaturated MgSO 4 droplets .…”

Section: Introductionmentioning

confidence: 99%

Understanding the Hygroscopic Properties of Supersaturated Droplets of Metal and Ammonium Sulfate Solutions Using Raman Spectroscopy

2001

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The hygroscopic properties of sulfate-containing particles are important to understanding the behavior of atmospheric aerosols. At high concentrations, chemical interactions between sulfate ions with the countercations are significant and lead to the formation of contact pairs. In this paper, Raman spectroscopy was used to study the structural changes of single aqueous droplets of equal molar Na2SO4/MgSO4 mixture, Na2SO4, (NH4)2SO4, MgSO4, ZnSO4, and CdSO4 in relation to their hygroscopic properties in an electrodynamic balance. The molar water-to-solute ratio (WSR) and the Raman spectra of droplets equilibrated at different ambient relative humidities were measured. When RH is reduced, the WSR of the Na2SO4/MgSO4 droplet decreases from 25.3 to 4.2 without crystallization but with two distinct transition points. The first one appears at WSR = 18.9, where the WSR is more sensitive to RH and the shoulder at 995 cm-1 of the ν1-SO4 2- band of the Raman spectrum shows an abrupt change in the ratio of the intensity at 995 cm-1 to that at 984 cm-1. This WSR is close to the minimum ratio (18) required to support the hexaaquo structures for both Mg2+ and Na+ ions. A mixture of the contact ion pairs of Mg2+O6 - x (SO4 2-)O x (H2O)·Na+O6 - y (SO4 2-)O y (H2O) (y < x < 6), which change the spectral characteristic of the shoulder at 995 cm-1, is formed. These contact ion pair mixtures share sulfate ions and water molecules, which invalidate empirical mixing rules of water activity of atmospheric aerosols such as the ZSR model. As RH is further reduced, the second transition point appears at WSR = 7.7, where the WSR becomes almost insensitive to RH and another shoulder at 1002 cm-1 appears in the spectrum. The mixture of the contact ion pairs finally evolves into the double salt of MgSO4·Na2SO4·4H2O, giving two new Raman peaks at 1007 and 1043 cm-1. Transitions of the hygroscopic properties coinciding with the formation of monodentates were also observed for MgSO4 and ZnSO4 droplets.

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An Infrared Study of Monosulfatopentaaquochromium(III) Chloride

Cited by 39 publications

References 1 publication

The rate of aquation of sulfatopentaaquochromium (III) ion in acidic, aqueous solution

The rate of aquation of sulfatopentaaquochromium (III) ion in acidic, aqueous solution

Study of Contact Ion Pairs of Supersaturated Magnesium Sulfate Solutions Using Raman Scattering of Levitated Single Droplets

Understanding the Hygroscopic Properties of Supersaturated Droplets of Metal and Ammonium Sulfate Solutions Using Raman Spectroscopy

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