Dissolution Thermodynamics of 1,2,3-Triazole Nitrate in Water

The enthalpies of dissolution of 1,2,3-triazole nitrate in water were measured using a RD496-2000 Calvet microcalorimeter at four different temperatures under atmospheric pressure. Differential enthalpies (Δ_dif H) and molar enthalpies (Δ_diss H) of dissolution were determined. The corresponding kinetic equations that describe the dissolution rate at the four experimental temperatures are \fracdadt / s ^{- 1} = 10 ^{- 3.75}( 1 - a)^0.96\frac{d\alpha}{dt} / \mathrm{s}^{ - 1} =10^{ - 3.75}( 1 - \alpha)^{0.96} (T=298.15 K), \fracdadt /s ^{- 1} = 10 ^{- 3.73}( 1 - a)^1.00\frac{d\alpha}{dt} /\mathrm{s}^{ - 1} = 10^{ - 3.73}( 1 - \alpha)^{1.00} (T=303.15 K), \fracdadt / s ^{- 1} = 10 ^{- 3.72}( 1 - a)^0.98\frac{d\alpha}{dt} / \mathrm{s}^{ - 1} = 10^{ - 3.72}( 1 - \alpha)^{0.98} (T=308.15 K) and \fracdadt / s ^{- 1} = 10 ^{- 3.71}( 1 -a)^0.97\frac{d\alpha}{dt} / \mathrm{s}^{ - 1} = 10^{ - 3.71}( 1 -\alpha)^{0.97} (T=313.15 K). The determined values of the activation energy E and pre-exponential factor A for the dissolution process are 5.01 kJ⋅mol⁻¹ and 10^−2.87 s⁻¹, respectively.     

Studies on electron transfer reactions: reduction of heteropoly 10-tungstodivanadophosphate by <Emphasis Type="SmallCaps">l</Emphasis>-cysteine in aqueous acid medium

l-cysteine undergoes facile electron transfer with heteropoly 10-tungstodivanadophosphate, [ \textPV^\textV \textV^\textV \textW _{1 0} \textO _{4 0} ]^{5 -} , \left[ {{\text{PV}}^{\text{V}} {\text{V}}^{\text{V}} {\text{W}}_{ 1 0} {\text{O}}_{ 4 0} } \right]^{5 - } , at ambient temperature in aqueous acid medium. The stoichiometric ratio of [cysteine]/[oxidant] is 2.0. The products of the reaction are cystine and two electron-reduced heteropoly blue, [PV^IVV^IVW₁₀O₄₀]⁷⁻. The rates of the electron transfer reaction were measured spectrophotometrically in acetate–acetic acid buffers at 25 °C. The orders of the reaction with respect to both [cysteine] and [oxidant] are unity, and the reaction exhibits simple second-order kinetics at constant pH. The pH-rate profile indicates the participation of deprotonated cysteine in the reaction. The reaction proceeds through an outer-sphere mechanism. For the dianion ⁻SCH₂CH(NH₃ ⁺)COO⁻, the rate constant for the cross electron transfer reaction is 96 M⁻¹s⁻¹ at 25 °C. The self-exchange rate constant for the ^- \textSCH₂ \textCH( \textNH₃ ⁺ )\textCOO ^- \mathord

Kinetics and mechanism of oxidation of aquaethylenediaminetetraacetatocobaltate(II) by <Emphasis Type="Italic">N</Emphasis>-bromosuccinimide in aqueous acidic solution

The oxidation of aquaethylenediaminetetraacetatocobaltate(II) [Co(EDTA)(H₂O)]⁻² by N-bromosuccinimide (NBS) in aqueous solution has been studied spectrophotometrically over the pH 6.10–7.02 range at 25 °C. The reaction is first-order with respect to complex and the oxidant, and it obeys the following rate law:

Dissolution properties of hexanitrohexaazaisowurtzitane (CL-20) in ethyl acetate and acetone

The enthalpies of dissolution in ethyl acetate and acetone of hexanitrohexaazaisowurtzitane (CL-20) were measured by means of a RD496-2000 Calvet microcalorimeter at 298.15 K, respectively. Empirical formulae for the calculation of the enthalpy of dissolution (Δ_diss H), relative partial molar enthalpy (Δ_diss H _partial), relative apparent molar enthalpy (Δ_diss H _apparent), and the enthalpy of dilution (Δ_dil H _1,2) of each process were obtained from the experimental data of the enthalpy of dissolution of CL-20. The corresponding kinetic equations describing the two dissolution processes were \frac\textda\textdt = 1.60 ×10 ^{- 2} (1 - a)^0.84 {\frac{{{\text{d}}\alpha }}{{{\text{d}}t}}} = 1.60 \times 10^{ - 2} (1 - \alpha )^{0.84} for dissolution process of CL-20 in ethyl acetate, and \frac\textda\textdt = 2.15 ×10 ^{- 2} (1 - a)^0.89 {\frac{{{\text{d}}\alpha }}{{{\text{d}}t}}} = 2.15 \times 10^{ - 2} (1 - \alpha )^{0.89} for dissolution process of CL-20 in acetone.     

Solubility Measurements of Crystalline NiO in Aqueous Solution as a Function of Temperature and pH

Results of solubility experiments involving crystalline nickel oxide (bunsenite) in aqueous solutions are reported as functions of temperature (0 to 350 °C) and pH at pressures slightly exceeding (with one exception) saturation vapor pressure. These experiments were carried out in either flow-through reactors or a hydrogen-electrode concentration cell for mildly acidic to near neutral pH solutions. The results were treated successfully with a thermodynamic model incorporating only the unhydrolyzed aqueous nickel species (viz., Ni²⁺) and the neutrally charged hydrolyzed species (viz., Ni(OH)₂⁰)\mathrm{Ni(OH)}_{2}^{0}). The thermodynamic quantities obtained at 25 °C and infinite dilution are, with 2σ uncertainties: log₁₀K_s0^o = (12.40 ±0.29),\varDelta_rG_m^o = -(70. 8 ±1.7)\log_{10}K_{\mathrm{s0}}^{\mathrm{o}} = (12.40 \pm 0.29),\varDelta_{\mathrm{r}}G_{m}^{\mathrm{o}} = -(70. 8 \pm 1.7) kJ⋅mol⁻¹; \varDelta_rH_m^o = -(105.6 ±1.3)\varDelta_{\mathrm{r}}H_{m}^{\mathrm{o}} = -(105.6 \pm 1.3) kJ⋅mol⁻¹; \varDelta_rS_m^o = -(116.6 ±3.2)\varDelta_{\mathrm{r}}S_{m}^{\mathrm{o}} =-(116.6 \pm 3.2) J⋅K⁻¹⋅mol⁻¹; \varDelta_rC_p,m^o = (0 ±13)\varDelta_{\mathrm{r}}C_{p,m}^{\mathrm{o}} = (0 \pm 13) J⋅K⁻¹⋅mol⁻¹; and log₁₀K_s2^o = -(8.76 ±0.15)\log_{10}K_{\mathrm{s2}}^{\mathrm{o}} = -(8.76 \pm 0.15); \varDelta_rG_m^o = (50.0 ±1.7)\varDelta_{\mathrm{r}}G_{m}^{\mathrm{o}} = (50.0 \pm 1.7) kJ⋅mol⁻¹; \varDelta_rH_m^o = (17.7 ±1.7)\varDelta_{\mathrm{r}}H_{m}^{\mathrm{o}} = (17.7 \pm 1.7) kJ⋅mol⁻¹; \varDelta_rS_m^o = -(108±7)\varDelta_{\mathrm{r}}S_{m}^{\mathrm{o}} = -(108\pm 7) J⋅K⁻¹⋅mol⁻¹; \varDelta_rC_p,m^o = -(108 ±3)\varDelta_{\mathrm{r}}C_{p,m}^{\mathrm{o}} = -(108 \pm 3) J⋅K⁻¹⋅mol⁻¹. These results are internally consistent, but the latter set differs from those gleaned from previous studies recorded in the literature. The corresponding thermodynamic quantities for the formation of Ni²⁺ and Ni(OH)₂⁰\mathrm{Ni(OH)}_{2}^{0} are also estimated. Moreover, the Ni(OH)₃ ^-\mathrm{Ni(OH)}_{3}^{ -} anion was never observed, even in relatively strong basic solutions (m_{OH ^-} = 0.1m_{\mathrm{OH}^{ -}} = 0.1 mol⋅kg⁻¹), contrary to the conclusions drawn from all but one previous study.     

Electrocatalytic oxidation of nitrite at a terpyridine manganese(II) complex modified carbon past electrode

A carbon past electrode modified with [Mn(H₂O)(N₃)(NO₃)(pyterpy)], ( \textpyterpy = 4￠- ( 4 - \textpyridyl ) - 2,2￠:\text6￠,\text2￠￠- \textterpyridine ) \left( {{\text{pyterpy}} = 4\prime - \left( {4 - {\text{pyridyl}}} \right) - 2,2\prime:{\text{6}}\prime,{\text{2}}\prime\prime - {\text{terpyridine}}} \right) complex have been applied to the electrocatalytic oxidation of nitrite which reduced the overpotential by about 120 mV with obviously increasing the current response. Relative standard deviations for nitrite determination was less than 2.0%, and nitrite can be determined in the ranges of 5.00 × 10⁻⁶ to 1.55 × 10⁻² mol L⁻¹, with a detection limit of 8 × 10⁻⁷ mol L⁻¹. The treatment of the voltammetric data showed that it is a pure diffusion-controlled reaction, which involves one electron in the rate-determining step. The rate constant k′, transfer coefficient α for the catalytic reaction, and diffusion coefficient of nitrite in the solution, D, were found to be 1.4 × 10⁻², 0.56× 10⁻⁶, and 7.99 × 10⁻⁶ cm² s⁻¹, respectively. The mechanism for the interaction of nitrite with the Mn(II) complex modified carbon past electrode is proposed. This work provides a simple and easy approach to detection of nitrite ion. The modified electrode indicated reproducible behavior, anti-fouling properties, and stability during electrochemical experiments, making it particularly suitable for the analytical purposes.     

Curing reaction of <Emphasis Type="Italic">o</Emphasis>-cresol-formaldehyde epoxy/LC epoxy(<Emphasis Type="Italic">p</Emphasis>-PEPB)/anhydride(MeTHPA)

The curing kinetics of a bi-component system about o-cresol-formaldehyde epoxy resin (o-CFER) modified by liquid crystalline p-phenylene di[4-(2,3-epoxypropyl) benzoate] (p-PEPB), with 3-methyl-tetrahydrophthalic anhydride (MeTHPA) as a curing agent, were studied by non-isothermal differential scanning calorimetry (DSC) method. The relationship between apparent activation energy E _a and the conversion α was obtained by the isoconversional method of Ozawa. The reaction molecular mechanism was proposed. The results show that the values of E _a in the initial stage are higher than other time, and E _a tend to decrease slightly with the reaction processing. There is a phase separation in the cure process with LC phase formation. These curing reactions can be described by the Šesták–Berggren (S–B) equation, the kinetic equation of cure reaction as follows: \frac\textda\textdt = Aexp( - \fracE_\texta RT )a^m ( 1 - a )ⁿ {\frac{{{\text{d}}\alpha }}{{{\text{d}}t}}} = A\exp \left( { - {\frac{{E_{\text{a}} }}{RT}}} \right)\alpha^{m} \left( {1 - a} \right)^{n} .     

Modeling of a voltammetric experiment in a limiting diffusion space

A voltammetric experiment confined in a limiting diffusion space is analyzed theoretically governed by conventional or time-anomalous factional diffusion under conditions of cyclic and square-wave voltammetry. The solution for conventional diffusion is derived by means of the Jacobi theta function Q( a²/p²t )( a = LD ^{- 1/2} \Theta \left( {{a^2}/{\pi^2}t} \right)\left( {a = L{D^{ - 1/2}}} \right. , where L is the thickness of the finite diffusion space, D is the diffusion coefficient, and t is the time of the experiment) and compared with the solution frequently used in the literature expressed in the form Θ(a ⁻² t). For L → ∞, the present solution converges to the one for the semi-infinite diffusion, thus being of a general applicability for both finite and semi-infinite diffusion. Hence, the mathematical model for simulation of both cyclic and square-wave voltammetric experiment provides significant advances in terms of simulation time and accuracy compared to the previous model based on the modified step-function method Mirčeski (J Phys Chem B 108:13719, 2004). For the fractional diffusion experiment, the solution is derived by combining an infinite series and the Wright function f( - a/2,a/2; - 2ax ^{- 1/2}t ^{- a/2} ) \phi \left( { - \alpha /2,\alpha /2; - 2a{\xi^{ - 1/2}}{t^{ - \alpha /2}}} \right) , where α is the time fractional parameter ranging over the interval 0 < a < 1 0 < \alpha < {1} , and ξ = 1 s^1−α is the auxiliary constant. The voltammetric properties of the experiment controlled by fractional diffusion are comparable for both finite and semi-infinite diffusion.     

Thermal decomposition kinetics of magnesite from thermogravimetric data

Thermal decomposition kinetics of magnesite were investigated using non-isothermal TG-DSC technique at heating rate (β) of 15, 20, 25, 35, and 40 K min⁻¹. The method combined Friedman equation and Kissinger equation was applied to calculate the E and lgA values. A new multiple rate iso-temperature method was used to determine the magnesite thermal decomposition mechanism function, based on the assumption of a series of mechanism functions. The mechanism corresponding to this value of F(a), which with high correlation coefficient (r-squared value) of linear regression analysis and the slope was equal to −1.000, was selected. And the Malek method was also used to further study the magnesite decomposition kinetics. The research results showed that the decomposition of magnesite was controlled by three-dimension diffusion; mechanism function was the anti-Jander equation, the apparent activation energy (E), and the pre-exponential term (A) were 156.12 kJ mol⁻¹ and 10^5.61 s⁻¹, respectively. The kinetic equation was

Calculating activation energy of amorphous phase with the Lambert W function

A new approach for determining the activation energy of amorphous alloys is developed. Setting the second order differential coefficient of heterogeneous reaction rate equation of non-isothermal heating as zero at extreme points of DSC curve, we obtain the new correlation taking form:

Ion-Solvation Behavior of Pyridinium Dichromate in Water–N,N-Dimethyl Formamide Solvent Mixtures

The electrical conductances of pyridinium dichromate have been measured in N,N-dimethyl formamide–water mixtures of different compositions in the temperature range 283–313 K. The limiting molar conductance, Λ₀, association constant of the ion pair, K _A, and dissociation constant K _C have been calculated using the Shedlovsky and Kraus–Bray equations. The effective ionic radii (r _i ) of C₅H₅NH⁺ and Cr₂O₇ ^-\mathrm{Cr}_{2}\mathrm{O}_{7}^{ -} have been determined from the L_i⁰\Lambda_{i}^{0} values using Gill’s modification of Stokes’ law. The influence of the mixed solvent composition on the solvation of ions is discussed with the help of the ‘R’-factor ( R = \frachL _±⁰(solvent)hL _±⁰(water)R = \frac{\eta \Lambda_{ \pm}^{0}(\mathrm{solvent})}{\eta\Lambda_{ \pm}^{0}(\mathrm{water})}). Thermodynamic parameters are evaluated and reported. The results of this study are interpreted in terms of ion–solvent interactions and solvent properties.     

The kinetics of the reduction of tetraoxoiodate(VII) by <Emphasis Type="Italic">n</Emphasis>-(2-hydroxylethyl)ethylenediaminetriacetatocobaltate(II) ion in aqueous perchloric acid

The stoichiometries, kinetics and mechanism of the reduction of tetraoxoiodate(VII) ion, IO₄ ⁻ to the corresponding trioxoiodate(V) ion, IO₃ ⁻ by n-(2-hydroxylethyl)ethylenediaminetriacetatocobaltate(II) ion, [CoHEDTAOH₂]⁻ have been studied in aqueous media at 28 °C, I = 0.50 mol dm⁻³ (NaClO₄) and [H⁺] = 7.0 × 10⁻³ mol dm⁻³. The reaction is first order in [Oxidant] and [Reductant], and the rate is inversely dependent on H⁺ concentration in the range 5.00 × 10⁻³ ≤ H⁺≤ 20.00 × 10⁻³ mol dm⁻³ studied. A plot of acid rate constant versus [H⁺]⁻¹ was linear with intercept. The rate law for the reaction is:

Stereo-dynamics study of O + HCl → OH + Cl reaction on the <Superscript>3</Superscript>A″, <Superscript>3</Superscript>A′, and <Superscript>1</Superscript>A′ states

Using three accurate potential energy surfaces of the ³A″, ³A′, and ¹A′ states constructed recently, we present a quasi-classical trajectory (QCT) calculation for O + HCl (v = 0, j = 0) → OH + Cl reaction at the collision energies (E _col) of 14.0–20.0 kcal/mol. The three angular distribution functions—P(q_r ) P(\theta_{r} ) , P(j_r ) P(\varphi_{r} ) , and P(q_r ,j_r ) P(\theta_{r} ,\varphi_{r} ) , together with the four commonly used polarization-dependent differential cross-sections, \frac2ps \fracds₀₀ dw_t , \frac2ps \fracds₂₀ dw_t , \frac2ps \fracds_{22 +} dw_t , \textand \frac2ps \fracds_{21 -} dw_t {\frac{2\pi }{\sigma }}\,{\frac{{d\sigma_{00} }}{{d\omega_{t} }}},\,{\frac{2\pi }{\sigma }}\,{\frac{{d\sigma_{20} }}{{d\omega_{t} }}},\,{\frac{2\pi }{\sigma }}\,{\frac{{d\sigma_{22 + } }}{{d\omega_{t} }}},\,{\text{and}}\,{\frac{2\pi }{\sigma }}\,{\frac{{d\sigma_{21 - } }}{{d\omega_{t} }}} are exhibited to get an insight into the alignment and the orientation of the product OH radical. There is a similar behavior of the tendency scattering direction for the two triplet electronic states (³A″ and ³A′)—backward scattering dominates, however, forward scattering prevails for the case of ¹A′ state. Also, obvious differences have been found in the stereo-dynamical information, which reveals the influences of the potential energy surface and the collision energy. The degrees of polarization and the influence of the collision energy on the stereo-dynamics characters of the title reaction are both demonstrated in the order of ³A′ > ³A″ > ¹A′.     

Ligament-like tough double-network hydrogel based on bacterial cellulose

Using the double-network (DN) method, bacterial cellulose/polyacrylamide (BC/PAAm) DN gels able to sustain not only high elongation but also high compression have been synthesized by combining BC gel as the first network with PAAm as the second network in the presence of N,N′-methylene bisacrylamide (MBAA) as a cross-linker. This DN gel was obtained by modifying the monomer concentration of the second network, acrylamide monomer (AAm) and MBAA, and by controlling the water content of the first network, BC gel. The mechanical properties are discussed in term of the swelling degree (q), which is independent of the concentration of AAm and MBAA. It was found that, for BC/PAAm DN gels with the first network formed from BC gel with high q (BC _q=120), the tensile and compressive modulus (E) scales with q as E μ q ^{- 2} E \propto q^{ - 2} . The tensile fracture stress, σ _F, of this DN gel was almost independent of q, that is s_\textF μ q⁰, \sigma_{\text{F}} \propto q^{0}, but the compressive fracture stress, σ _F, scaled with q as E μ q ^{- 2} E \propto q^{ - 2} . Meanwhile, the tensile and compressive fracture strain (ε _F) of the gel is almost independent of q, which is caused by AAm concentration change, but linearly increased with q, which is caused by MBAA concentration change. Furthermore, by decreasing the water content of the BC gel prior to polymerization of the second (PAAm) network, a ligament-like tough BC/PAAm DN gel could be obtained with tensile strength of 40 MPa.     

Evaporation Analogies Between Light Hydrocarbons Effect of Molecular Mass of Purge gas

The evaporation of benzene, cyclohexane, n-heptane, toluene, 2-xylene, 3-xylene and 4-xylene was studied in H₂, He, N₂ or CO₂ as purge gases for control of the introduced methods of evaluation and the sensitivity limits of TG measurements. I_i as a function of (1−α) and the following equation proved very suitable for a quantitative comparison of 28 independent and different TG measurements and for a very sensitive characterization of the thermal processes, even within an energy level difference of 3 kJ mol⁻¹, in spite of the known great inconsistency in the formal kinetic parameters:

Specific adsorption of bromide and iodide ions from N-methyl formamide solutions with constant ionic strength on liquid ga electrode

The differential capacitance curves were measured with an ac bridge in the Ga/[N-MF + 0.1 m M KBr + 0.1 (1 − m) M KClO₄] and Ga/[N-MF + 0.1 m M KI + 0.1 (1 − m) M KClO₄] systems at the following fractions m of surface-active anions: 0, 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, and 1. As compared with other solvents, N-methyl formamide (N-MF) enables one to realize the largest positive charges of Ga electrode, at which it remains ideally polarizable (up to 20 μ/cm²). The data on the specific adsorption of Br⁻ and I⁻ anions in the system can be quantitatively described by the Frumkin’s isotherm; to the first approximation, free energy of halide ion (Hal⁻) adsorption DG_{adsHal ^{- 1}} \Delta G_{adsHal^{ - 1} } is a linear function of electrode charge. It is found that, in contrast to the Hg/N-MF interface, DG_{adsHal ^{- 1}} \Delta G_{adsHal^{ - 1} } at the Ga/N-MF interface varies in the reverse order: Br^t— ∼ I⁻ < Cl⁻. From the measured results, we can conclude that the energy of metal-Hal⁻ interaction increases in series: $\Delta G_{M - Cl^ - } > \Delta G_{M - Br^ - } > \Delta G_{M - I^ - } $\Delta G_{M - Cl^ - } > \Delta G_{M - Br^ - } > \Delta G_{M - I^ - } and the difference (DG_{Ga - Hal1^-} - DG_{Ga - Hal2^-} )(\Delta G_{Ga - Hal_1^ - } - \Delta G_{Ga - Hal_2^ - } ) is larger than the difference between the solvation energies of Hal^- (DG_{S - Hal1^-} - DG_{S - Hal2^-} )Hal^ - (\Delta G_{S - Hal_1^ - } - \Delta G_{S - Hal_2^ - } ).     

Thermochemistry of 2-Aminopyridine (C<Subscript>5</Subscript>H<Subscript>6</Subscript>N<Subscript>2</Subscript>)(s)

The molar enthalpies of solution of 2-aminopyridine at various molalities were measured at T=298.15 K in double-distilled water by means of an isoperibol solution-reaction calorimeter. According to Pitzer’s theory, the molar enthalpy of solution of the title compound at infinite dilution was calculated to be D_solH_m^￥ = 14.34 kJ·mol^-1\Delta_{\mathrm{sol}}H_{\mathrm{m}}^{\infty} = 14.34~\mbox{kJ}\cdot\mbox{mol}^{-1}, and Pitzer’s ion interaction parameters b_MX^(0)L, b_MX^(1)L\beta_{\mathrm{MX}}^{(0)L}, \beta_{\mathrm{MX}}^{(1)L}, and C_MX^fLC_{\mathrm{MX}}^{\phi L} were obtained. Values of the relative apparent molar enthalpies ( ^φ L) and relative partial molar enthalpies of the compound ([`(L)]₂)\bar{L}_{2}) were derived from the experimental enthalpies of solution of the compound. The standard molar enthalpy of formation of the cation C₅H₇N₂ ⁺\mathrm{C}_{5}\mathrm{H}_{7}\mathrm{N}_{2}^{ +} in aqueous solution was calculated to be D_fH_m^o(C₅H₇N₂⁺,aq)=-(2.096±0.801) kJ·mol^-1\Delta_{\mathrm{f}}H_{\mathrm{m}}^{\mathrm{o}}(\mathrm{C}_{5}\mathrm{H}_{7}\mathrm{N}_{2}^{+},\mbox{aq})=-(2.096\pm 0.801)~\mbox{kJ}\cdot\mbox{mol}^{-1}.     

The Estimation of Standard Molar Enthalpies of Solution for VOSO<Subscript>4</Subscript>⋅<Emphasis Type="Italic">n</Emphasis>H<Subscript>2</Subscript>O(s) in Water and in Aqueous H<Subscript>2</Subscript>SO<Subscript>4</Subscript>

The molar enthalpies of solution of VOSO₄⋅3.52H₂O(s) at various molalities in water and in aqueous sulfuric acid (0.1 mol⋅kg⁻¹), Δ_sol H _m, were measured by a solution-reaction isoperibol calorimeter at 298.15±0.01 K. An improved Archer’s method to estimate the standard molar enthalpy of solution, D_solH⁰_m\Delta_{\mathrm{sol}}H^{0}_{\mathrm{m}}, was put forward. In terms of the improved method, the values of D_solH⁰_m=-24.12±0.03 kJ·mol^-1\Delta_{\mathrm{sol}}H^{0}_{\mathrm{m}}=-24.12\pm 0.03~\mbox{kJ}{\cdot}\mbox{mol}^{-1} of VOSO₄⋅3.52H₂O(s) in water and D_solH⁰_m=-15.38±0.06 kJ·mol^-1\Delta_{\mathrm{sol}}H^{0}_{\mathrm{m}}=-15.38\pm 0.06~\mbox{kJ}{\cdot}\mbox{mol}^{-1} in aqueous sulfuric acid were obtained, respectively. The data indicates that the energy state of VOSO₄ in aqueous H₂SO₄ is higher than that in pure water.     

Dynamics of Hydration of Alkylsulfonate Anions in Aqueous Solutions

The ¹⁷O-NMR spin-lattice relaxation times (T ₁) of water molecules in aqueous solutions of n-alkylsulfonate (C₁ to C₆) and arylsulfonic anions were determined as a function of concentration at 298 K. Values of the dynamic hydration number, (S^-) = n_h ^- (t_c^- /t_c⁰ - 1)(\mathrm{S}^{-}) = n_{\mathrm{h}}^{ -} (\tau_{\mathrm{c}}^{-} /\tau_{\mathrm{c}}^{0} - 1), were determined from the concentration dependence of T ₁. The ratios (t_c ^-/t_c⁰\tau_{\mathrm{c}}^{ -}/\tau_{\mathrm{c}}^{0}) of the rotational correlation times (t_c ^-\tau_{\mathrm{c}}^{ -} ) of the water molecules around each sulfonate anion in the aqueous solutions to the rotational correlation time of pure water (t_c⁰\tau_{\mathrm{c}}^{0}) were obtained from the n _DHN(S⁻) and the hydration number (n_h ^-n_{\mathrm{h}}^{ -} ) results, which was calculated from the water accessible surface area (ASA) of the solute molecule. The t_c ^-/t_c⁰\tau_{\mathrm{c}}^{ -}/\tau_{\mathrm{c}}^{0} values for alkylsulfonate anions increase with increasing ASA in the homologous-series range of C₁ to C₄, but then become approximately constant. This result shows that the water structures of hydrophobic hydration near large size alkyl groups are less ordered. The rotational motions of water molecules around an aromatic group are faster than those around an n-alkyl group with the same ASA. That is, the number of water–water hydrogen bonds in the hydration water of aromatic groups is smaller in comparison with the hydration water of an n-alkyl group having the same ASA. Hydrophobic hydration is strongly disturbed by a sulfonate group, which acts as a water structure breaker. The disturbance effect decreases in the following order: $\mbox{--} \mathrm{SO}_{3}^{-} > \mbox{--} \mathrm{NH}_{3}^{ +} > \mathrm{OH}> \mathrm{NH}_{2}$\mbox{--} \mathrm{SO}_{3}^{-} > \mbox{--} \mathrm{NH}_{3}^{ +} > \mathrm{OH}> \mathrm{NH}_{2}. The partial molar volumes and viscosity B _V coefficients for alkylsulfonate anions are linearly dependent on their n _DHN(S⁻) values.     

Thermodynamic properties of the ternary oxides in the Eu–Ru–O system by using solid-state electrochemical cells

The Gibbs free energies of formation of Eu₃RuO₇(s) and Eu₂Ru₂O₇(s) have been determined using solid-state electrochemical technique employing oxide ion conducting electrolyte. The reversible electromotive force (e.m.f.) of the following solid-state electrochemical cells have been measured: