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liuyunruoyan木虫 (著名写手)
小小木虫
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【求助】一段英文翻译，（英译汉）【有效期至2009年4月3日晚】
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Values of Sstruc for the alkali metal and halide ions as well as Ag+ and ClO4- were reported on the unusual mole fraction scale for the solution, with S∞(H+,aq) = -68.2 J K-1 mol-1 on this scale, causing K+ to appear as a structure making ion. Adjustment to the molar scale with S∞(H+,aq)= -22.2 J K-1 mol-1 corrects this unacceptable result. Abraham et al.153 noted the usual linear correlation of their ΔSstruc with the viscosity Bη coefficients as well with the BNMR coefficients (see section 5.2.1) and also with the ionic partial molar volumes or their electrostricted volumes. Bhattacharya199 inverted the correlations of ΔSstruc with Bη and BNMR, with ionic values for the latter two parameters obtained according to his method of splitting electrolyte data into ionic contributions (section 5.2.1), to calculate ionic entropies of hydration, but they did not discuss the effects of the ions on the water structure from the resulting values. Marcus and Loewenschuss200 and Marcus201 suggested yet another model for obtaining ΔSstruc values from ΔhydrS∞ ones, pointing out that ΔhydrS∞, with the standard state of 0.1 MPa for the ideal gaseous ions and 1 mol dm-3 for the aqueous ones, includes an irrelevant entropy of compression of ΔcompS =-26.7 J K-1 mol-1 that ought to be removed from the absolute ΔhydrS∞ values (based on S∞(H+,aq)=-22.2 J K-1 mol-1). The electrostatic effect beyond the first hydration shell was obtained as above, ΔSel =(NAe2/8πε0)z2(r +dW)-1εr-1(∂ ln εr/∂T)P, from the Born expression. However, within this hydration shell the n water molecules are translationally immobilized, having to move together with the ion Xz, with a concomitant reduction of their entropy. This contribution Δtr imS(Xz)=1.5R ln[M(X(H2O)n/M(X)]-26.0n (16) where the first term denotes the change of translational entropy due to the larger mass (M) of the hydrated ion and 26.0 is the molar translational entropy of water in its liquid form, does not pertain to the water structural effects either.The value of n= A|z|/(r/nm) with A = 0.355 was obtained empirically, so as to yield ΔSstruc(Na+)=ΔhydrS∞(Na+)-ΔcompS-ΔSel(Na+)-Δtr imS(Na+)=0 (17) on the supposition that sodium ions are indifferent with respect to the water structure making and breaking. In view of the cumulative errors incurred in such calculations, only values of ΔSstruc(Xz)/J K-1 mol-1 > 6 were construed as indicating the ion Xz to be definitely water structure breaking, values < -6 were construed as indicating it to be structure making, and in between values were construed to be borderline cases, including those for Na+, Ag+, and Cl-. The assignments201 of ions to such classes generally conformed to assignments by other methods, such as the signs of Bη and BNMR. Other models and approaches for obtaining the water structural effects of ions from the entropies of hydration, such as those of Uhlich, Ryabukhin, and Friedman andKrishnan,were briefly reviewed by Marcus and Loewenschuss and need not be detailed here. A final development of this concept for ΔSstruc that indicates the water structural effects of ions is due to Marcus,resembling more that of Abraham et al. than his own previous one. It is based on a model common for various thermodynamic functions of ion hydration, with the key quantity being Δr, the width of the electrostricted hydration shell, where the water molecules have a volume πdW3/6 rather than VW/NA. Thus, Δr is obtained from the volume of the hydration shell with n water molecules: (4π/3)[(r+Δr)3-r3]=nπdW3/6 (18) with n= A|z|/(r/nm) as before, A=0.36 being slightly different, and dW= 0.276 nm. Then the structural entropy is obtained from ΔSstruc=ΔhydrS∞-[ΔSnt+ΔSel 1+ΔSel 2] (19) Here the term ΔSnt takes care of the entropic effect of the creation of a cavity in the water to accommodate the ionΔSn as well as the compression term ΔcompS of the previous models. It is evaluated from the entropies of hydration of small neutral molecules or rare gas atoms, interpolated for a radius r the same as that of the ion: ΔSnt =-3 - 600(r/nm) J K-1 mol-1. In analogy with eq 15, the electrostatic effects are ΔSel 1=(NAe2/8πε0)z2[Δr(r+Δr)-1]ε-2(∂ε/ ∂ T)P (20a) ΔSel 2=(NAe2/8πε0)z2(r+Δr)-1εr-2(∂εr/ ∂ T)P (20b) The former of these two expressions (eq 20a) pertains to the electrostricted hydration shell, where the permittivity and its temperature derivative are assumed to have the infinitely large field value of ε′ =nD2= 1.776 and (∂ε′/∂T)P = 2(∂nD/∂T)P = -1 × 10-4 K-1 at 25 °C, where nD is the refractive index of water at the sodium D line. This treatment could be applied to nearly 150 aqueous cations and anions, monatomic and polyatomic, with charges -4 e z e 4. Sodium and silver cations now reverted to the structure making category and chloride to the structure breaking one, but the borderline region is widened to (20 J K-1 mol-1. The linear correlation with the viscosity Bη (except for tetraalkylammonium cations) is ΔSstruc/J K-1 mol-1=20(z2+|z|)-605(Bη/dm3 mol-1) (21) Values of ΔSstruc of representative ions obtained according to the treatments of Krestov as reported in ref 196 and by Abraham et al. and Marcus are shown in Table 7, adjusted where applicable to the M scale for the entropies of hydration and based on their absolute values with S∞(H+,aq)= -22.2 J K-1 mol-1. A treatment based on the same model, but dealing with the structural heat capacity, ΔCP struct, contribution of the effects of ions on the water structure was also repotted by Marcus. Here CP replaced S in eqs 19 and 20a, ΔCP nt =-48 + 1380(r/nm) J K-1 mol-1, and T(∂2ε′/∂T2)P and T(∂2εr/ ∂T2)P replaced the corresponding factors in eqs 20a and 20b. A negative bias occurred in ΔCP struct calculated in this manner, due to the choice of CP ∞(H+,aq)= - 71 J K-1 mol-1, and in order to show the structure making andbreaking properties of the ions, 175z J K-1 mol-1 are added here, to yield the values shown in Table 7, with positive values for structure making ions and negative ones for structure breaking ones, but allowing for a wide borderline region of (60 J K-1 mol-1. |
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6楼2009-04-03 23:40:36
mayong11
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在不同的摩尔分数范围的S ∞ （ H +，aq） = -68.2 J K - 1的溶液中，碱金属和碱土金属卤化物离子以及银离子和高氯酸离子的Sstruc值被报告，造成钾离子程现出一种发展的结构。调整溶液的摩尔范围使出现S ∞ （ H +，aq） = -22.2 J K - 1纠正了这一令人无法接受的结果。亚伯拉罕等人指出ΔSstruc同粘度Bη系数以及与BNMR系数（见5.2.1 ），并与离子部分摩尔体积或其静电体积呈通常的线性相关。 Bhattacharya通过反向的ΔSstruc与Bη和BNMR的相关性，后两个参数的离子值由它的电解质很快溶解成离子的方法获得（第5.2.1 ），计算出了离子水化熵，但他们没有通过结果讨论离子对水结构的影响。 马库斯，Loewenschuss和Marcus建议从ΔhydrS ∞获得ΔSstruc值的又一模型，指出ΔhydrS∞ ，是具有0.1兆帕的理想气体分子离子和1mol/dm3的水的标准状态的，包括一个无关紧要压缩熵ΔcompS =- 26.7 J K - 1 ，应该从绝对ΔhydrS ∞值中扣除（基于S ∞ （ H +的，aq） =- 22.2 J K - 1 ）。超出了第一水和作用壳的静电效果获得如上， ΔSel =(NAe2/8πε0)z2(r +dW)-1εr-1(∂ ln εr/∂T)P，从最初的表达。 然而，在水和作用壳内，N个水分子是固定化，其移动与离子Xz有关 ，并同时减少其熵。这种贡献：Δtr imS(Xz)=1.5R ln[M(X(H2O)n/M(X)]-26.0n (16) [ Last edited by mayong11 on 2009-4-3 at 15:26 ] |
4楼2009-04-03 14:53:25
stred
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5楼2009-04-03 22:46:27
liuyunruoyan
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自己搞定了，放弃求助 7楼2009-04-04 10:58:25
