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  • 1
    Electronic Resource
    Electronic Resource
    The volume and compressibility change for the formation of the LaSO 4 + ion pair at 25°C (1977)
    Springer
    Journal of solution chemistry 6 (1977), S. 589-607 
    Details
    ISSN: 1572-8927
    Keywords: Lanthanum sulfate ; magnetic float densimeter ; sound velocimeter ; density ; apparent molal volume ; adiabatic apparent molal compressibility ; ion pair ; electrostriction ; hydration number
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The apparent molal volumes (φv) and adiabatic compressibilities [φK(S)] of La2(SO4)3 solutions have been determined from density and sound speed data at 25°C. The large positive deviations of φv and φK(S) of La2(SO4)3 from the limiting law have been attributed to the formation of the ion pair LaSO 4 + . The observed values of φv and φK(S) have been used to estimate the change in the apparent molal volume and adiabatic compressibility for the formation of LaSO 4 + from $$\Delta \phi (LaSO_4^ + ) = [\phi (obs.) - \phi (2La^{3 + } ,3SO_4^{2 - } )]/\alpha$$ where ϕ(2La3+, 3SO 4 2− ) is the apparent molal volume or adiabatic compressibility of the free ions, and α is the degree of association. The value of $$\Delta \phi _v^o (LaSO_4^ + ) = \Delta \bar V^o (LaSO_4^ + ) = 22.8 \pm 1cm^3 - mole^{ - 1}$$ and $$\Delta \phi _{K(S)}^o (LaSO_4^ + ) = \Delta \bar K_S^o (LaSO_4^ + ) = 85 \pm 20 \times 10^{ - 4} cm^3 - mole^{ - 1} - bar^{ - 1}$$ at infinite dilution are in reasonable agreement with the values determined from the high-pressure conductance data of Fisher and Davis. The number of hydrated water molecules (ca. 11) associated with the formation of LaSO 4 + determined from the volume and compressibility data are in good agreement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00655373
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  • 2
    Electronic Resource
    Electronic Resource
    The enthalpy of formation of magnesium sulfate ion pairs (1975)
    Springer
    Journal of solution chemistry 4 (1975), S. 145-159 
    Details
    ISSN: 1572-8927
    Keywords: Enthalpy ; dilution ; ion pairs ; lithium, sodium, and potassium chlorides and sulfates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The enthalpies of dilution of lithium, sodium, potassium, and magnesium chloride and sulfate solutions in the range 0.1 to 1.0 m have been measured at 30°C with a microcalorimeter. The relative apparent enthalpies φL of these solutions have been determined with the aid of an extended form of the Debye-Hückel limiting law $$\phi _L = S_H I^{1/2} [1/(1 + I^{1/2} ) - (\sigma /3)] + {\rm B}{\rm I} + CI^{3/2} $$ whereS H is the limiting-law slope, σ = 3/I3/2 × [(1+I1/2 − 1/(1+I1/2 − 2 ln (2+I1/2)], andB andC are empirical constants. This equation fits the experimental results to within a standard deviation of 2 cal-mole−1 for all the salts. The measured φL for the MgSO4 solutions were compared to those calculated using the additivity principle, φL(MgCl2) + φL(Na2SO4) − 2φL(NaCl), and the extended Debye-Hückel equation. The results of this comparison have been used to calculate the ΔH A o for the formation of MgSO 4 0 . A value of ΔH A o = 1.15 to 1.36 was obtained, depending upon the φL estimates for the free ions Mg2+ and SO 4 2− . The results are briefly discussed and compared to the results obtained by other workers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00649155
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  • 3
    Electronic Resource
    Electronic Resource
    The partial molal volume and compressibility change for the formation of the calcium sulfate ion pair at 25°C (1977)
    Springer
    Journal of solution chemistry 6 (1977), S. 269-280 
    Details
    ISSN: 1572-8927
    Keywords: Calcium sulfate ; molal volume and compressibility ; ion pair
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The apparent molal volumes (φv) and compressibilities (φK) of CaSO4 solutions have been determined at 25°C from precise density and sound-speed measurements. The large deviations of the values of φv and φK from the limiting law and various additivity estimates for the free ions (Ca2+, SO 4 2− ) have been used to estimate the partial molal volume ( $$\Delta \bar V^\circ $$ ) and compressibility ( $$\Delta \bar K^\circ $$ ) for the formation of the CaSO 4 0 ion pair. Values of $$\Delta \bar V^\circ $$ = 25 ± 3 cm3-mole−1 and $$\Delta \bar K^\circ $$ = (54±21)×10−4 cm3-mole−1-bar−1 were found. Since these values are larger than the value for the formation of MgSO 4 0 , the results indicate that more inner-sphere ion pairs are formed when SO 4 2− complexes with Ca2+ than with Mg2+. Using a simple model for ion-water interactions, the percent of inner-sphere or contact ion pairs in CaSO4 solutions is estimated to be 36 to 37%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645458
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  • 4
    Electronic Resource
    Electronic Resource
    Heat capacity changes for the lonization of aqueous phenols at 25°C (1976)
    Springer
    Journal of solution chemistry 5 (1976), S. 263-268 
    Details
    ISSN: 1572-8927
    Keywords: Molal volume ; heat capacity ; phenol ; nitrophenols ; cyanophenols ; sodium salts ; ionization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The apparent molal heat capacities $$\phi _{{\text{C}}_p }$$ have been determined at 25°C for phenol,meta-nitrophenol,para-nitrophenol,meta-cyanophenol, andpara-cyanophenol and the corresponding sodium salts in water at several concentrations. These values have been extrapolated to infinite dilution to provide the $$\bar C_p^o$$ values from which the heat capacity changes for the ionization of the aqueous phenols have been calculated. The observed $$\Delta \bar C_{p_i }^o$$ values are virtually identical within experimental error for the phenols studied. The volume data needed to calculate the $$\phi \bar C_p$$ values from the experimental data are also reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645464
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  • 5
    Electronic Resource
    Electronic Resource
    The enthalpies of dilution of phosphate solutions at 30°C (1978)
    Springer
    Journal of solution chemistry 7 (1978), S. 877-889 
    Details
    ISSN: 1572-8927
    Keywords: Ionization of phosphoric acid ; enthalpy of dilution ; phosphate solutions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The enthalpies of dilution of aqueous solutions of HCl, H3PO4, NaOH, NaH2PO4, Na2HPO4 and Na3PO4 in the molality range 0.1 to 1.0 mole-kg−1 have been determined at 30°C. The relative apparent molal enthalpies φL of HCl, NaOH, NaH2PO4 and Na2HPO4 have been determined with the aid of an extended form of the Debye-Hückel limiting law. The relative apparent molal enthalpies for Na3PO4 solutions have been corrected for hydrolysis. A value of ΔH H o =9525±150 cal-mole−1 was determined for the heat of hydrolysis of PO 4 −3 . This value gives ΔH 3 o =3815±150 cal-mole−1 for the ionization of H2PO 4 − , which is in good agreement with the value of ΔH 3 o =3500±500 cal-mole−1 determined directly by Pitzer at 25°C. The relative apparent molal enthalpies for H3PO4 solutions have been corrected for ionization. A value of ΔH 1 o =−1900±150 cal-mole−1 was obtained for the heat of ionization of H3PO4 to H++H2PO 4 − . This value is in good agreement with the value of ΔH 1 o =−2031 cal-mole−1 at 30°C determined by Harned and Owen from the temperature coefficient of the equilibrium constant and ΔH 1 o =−1950±80 cal-mole−1 at 25°C determined from calorimetry by Pitzer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645297
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