共查询到20条相似文献，搜索用时 125 毫秒
1.
2.
基于广义热力学基本理论,通过考虑塑性剪切变形产生的能量一部分以塑性自由能的形式储存,并且该部分自由能与超固结度相关,结合修正剑桥模型的热力学函数形式建立了适用于超固结土的自由能函数和耗散函数。该耗散函数与当前应力状态无关,相关联流动法则仍然适用。由建立的耗散函数和自由能函数,推导了弹塑性本构关系的屈服函数、流动法则、硬化定律。通过4种不同超固结土的试验结果和计算结果进行比较,验证了模型的合理性。 相似文献
3.
碳酸盐岩作为一种化学岩类其物性受成岩作用的影响十分明显,溶解作用是否发育直接关系到碳酸盐岩储层质量的好坏。碳酸盐矿物在埋藏环境中的溶解度与地层水的化学成分、环境的温度、pH等有着密切的关系。利用地层水化学资料,根据化学热力学的理论,通过方解石及白云石与地层水作用的平衡反应,计算吉布斯自由能变化ΔG,以此来判断方解石及白云石的溶解趋势,并建立了封闭系统中这两种矿物与水作用的热力学模型。根据这个理论模型,对塔北地区159口井奥陶系及6口井的寒武系地层水进行了ΔG的计算,结果显示,塔北地区碳酸盐岩与地层水反应的ΔG基本为负值,表明该地区总体处于碳酸盐岩溶解的环境,寒武系白云岩反应的自由能小于奥陶系灰岩,即在这种深埋条件下白云岩比灰岩更易溶解,这一点在实际岩芯资料上及前人的实验模拟中均有显示。塔北于奇地区自由能的计算结果也为负值,说明该地区强烈的充填作用并非发生在现今条件下,于奇地区现今的埋藏环境是有利于碳酸盐矿物溶解的,这一结论也在该地区奥陶系及寒武系岩芯上得到了验证。 相似文献
4.
作者利用FeO-Fe_2O_3-SiO_2系中包含莱河矿的Schreinemakers线锥,讨论了莱河矿生成自由能所应该满足的限制。结果表明,王声远计算的莱河矿标准生成自由能数据较为合理。 相似文献
5.
本文简要介绍了矿物溶解度Ｓ的电导测定及其从Ｓ计算溶度积Ｋｓｐ的方法、从反应的自由能ΔｒＧｍ＾Φ计算矿物的Ｋｓｐ。附表给出了笔者根据文献数据计算的部分矿物的Ｋｓｐ。与文献值比较,计算值是可信的,表中还提供了许多文献中难以查到的溶度积常数。 相似文献
6.
7.
蒙脱石伊利石化过程中伊-蒙混层形成的Gibbs自由能 总被引：3，自引：0，他引：3
采用Vieillard(2000)提出的计算含水粘土矿物形成的Gibbs自由能的方法，对热液蚀变作用下蒙脱石向伊利石转变过程中伊利石．蒙脱石混层形成的Gibbs自由能进行了计算。根据伊利石-蒙脱石混层的化学成分，详细计算了一个端元伊利石样品形成的Gibbs自由能，其值为-5401．36kJ／mol。该值与已给出的天然伊利石和理想伊利石形成的Gibbs自由能非常相近，表明Vieillard(2000)的方法对计算伊利石-蒙脱石混层形成的Gibbs自由能是可行的。伊利石-蒙脱石形成的Gibbs自由能可进一步用于计算因地下水过量开采而产生的地面沉降的量。 相似文献
8.
为了研究页岩对气体的吸附机理,在50℃、60℃、80℃ 3个温度点对贵州凤参1井和天马1井的页岩样品进行等温吸附实验,并绘制出了CH4和CO2等温吸附曲线图,计算得到页岩表面自由能,从自由能角度分析页岩对CH4和CO2气体的吸附特性。研究结果表明:当温度一定时,随着压力的增加,页岩对2种气体的表面自由能变化值均呈现出不断增加的趋势,当压力一定时,随着温度的增加,表面自由能会逐渐减小,这与等温吸附曲线上气体吸附量随压力的变化是一致的;页岩对CO2的表面自由能变化值均要大于CH4,表明页岩对CO2的吸附能力比CH 4 更强,可以通过向页岩层中注入CO2来提高采收率;对于吸附能力较强的页岩气藏,可以通过注入表面活性剂的方法,增强活性剂与页岩表面的结合能力,降低CH4占有面积及其与页岩的表面自由能,以此达到促使CH4解吸的目的。 相似文献
9.
从自由能计算判别硅酸盐熔融体之不混溶 总被引：1，自引：0，他引：1
硅酸盐熔融体发生两液相不混溶可以产生一个富金属相,即矿浆和一个富硅相,即岩浆。这对研究矿浆成因是非常重要的。 Currie曾提出一个方法,根据计算一个硅酸盐熔体分成两液相之前和之后的自由能负值(—G),就可以判别它是否能分成两液相。 作者用Philpotts的岩石分析数据进行了自由能的计算,证实了Currie作法的正确。 作者利用学生合成的人造硅酸盐熔体数据,加以计算,绝大部分是分成两液相的。著名的基鲁纳瓦拉铁矿数据计算结果支持了矿浆成矿论点。 相似文献
10.
方解石在成岩环境中的溶解度与地下水化学特征、温度等有着极为密切的关系。通过CaCO3溶解沉淀反应平衡以及地下水中的Ca2+活度可以确定不同温压的地下水条件下方解石的溶解趋势。地下水溶液的pH值和温度是方解石溶解度最直接的控制因素。方解石溶解趋势可以通过CaCO3电离反应的吉布斯自由能(ΔG)来判断:ΔG<0时,反应向溶解方向进行;ΔG>0时,反应向沉淀方向进行。根据方解石的水岩反应理论,对塔河油田34口井的奥陶系地层水进行了ΔG的统计计算。结果显示:塔河油田现今地下水条件有利于方解石的溶解,西部地区较东部溶解趋势强,北部地区溶解趋势相对较弱。这为定量了解塔河地区埋藏岩溶趋势及该地区的储层评价预测提供了理论依据。 相似文献
11.
A parameter called ΔO2? is defined as the difference between the Gibbs energy of formation from the elements of a crystalline oxide and the Gibbs energy of formation from the elements of its cation in aqueous solution (per O2? in the oxide). Another parameter called Δ hydroxide is defined as the difference between the Gibbs energies of formation of an hydroxide and its constituent oxides, H2O oxide being considered as ice. A linear equation for 32 hydroxides, using these two parameters is: Δhydroxide = ?0.210 (ΔO2? cation ? ΔO2? H+). This relation can also be expressed in terms of solution energies. The solution energy of an hydroxide is a linear function of the solution energy of the corresponding oxide. The equation above can be used to predict values for Gibbs energies of formation of hydroxides, oxides or aqueous cations and to test the consistency of existing Gibbs energy values. 相似文献
12.
A method for the prediction of Gibbs free energies of formation for minerals belonging to the alunite family is proposed, based on an empirical parameter ΔGO= Mz+(c) characterizing the oxygen affinity of the cation Mz+. The Gibbs free energy of formation from constituent oxides is considered as the sum of the products of the molar fraction of an oxygen atom bound to any two cations, multiplied by the difference of oxygen affinity ΔGO= Mz+(c) between any two consecutive cations. The ΔGO= Mz+(c) value, using a weighing scheme involving the electronegativity of a cation in a specific site (12-fold coordination site, octahedral and tetrahedral) is assumed to be constant. It can be calculated by minimizing the difference between experimental Gibbs free energies (determined from solubility measurements) and calculated Gibbs free energies of formation from constituent oxides. Results indicate that this prediction method gives values within 0.5% of the experimentally measured values. The relationships between ΔGO= Mz+(alunite) corresponding to the electronegativity of a cation in either dodecahedral sites, octahedral sites or tetrahedral sites and known as ΔGO= Mz+(aq) were determined, thereby allowing the prediction of the electronegativity of rare earth metal ions and trivalent ions in dodecahedral sites and highly charged ions in tetrahedral sites. This allows the prediction of Gibbs free energies of formation of any minerals of the alunite supergroup (bearing various ions located in the dodecahedral and tetrahedral sites). Examples are given for hydronium jarosite and hindsalite, and the results appear excellent when compared to experimental values. 相似文献
13.
A parameter GO2– is defined as the difference between the Gibbs free energy of formation from the elements of a given oxide and its corresponding aqueous cation. The Gibbs free energies of formation of compounds such as sulfates, nitrates or carbonates, from their constituent oxides, are shown to be linear functions of GO2– values of their constituent cations. 相似文献
14.
Inorganic species in geologic fluids: correlations among standard molal thermodynamic properties of aqueous ions and hydroxide complexes 总被引：2，自引：0，他引：2
Correlations among experimentally determined standard partial molal thermodynamic properties of inorganic aqueous species at 25 degrees C and 1 bar allow estimates of these properties for numerous monatomic cations and anions, polyatomic anions, oxyanions, acid oxyanions, neutral oxy-acid species, dissolved gases, and hydroxide complexes of metal cations. Combined with correlations among parameters in the revised Helgeson-Kirkham-Flowers (HKF) equation of state (Shock et al., 1992), these estimates permit predictions of standard partial molal volumes, heat capacities, and entropies, as well as apparent standard partial molal enthalpies and Gibbs free energies of formation to 1000 degrees C and 5 kb for hundreds of inorganic aqueous species of interest in geochemistry. Data and parameters for more than 300 inorganic aqueous species are presented. Close agreement between calculated and experimentally determined equilibrium constants for acid dissociation reactions and cation hydrolysis reactions supports the generality and validity of these predictive methods. These data facilitate the calculation of the speciation of major, minor, and trace elements in hydrothermal and metamorphic fluids throughout most of the crust of the Earth. 相似文献
15.
SUN Xiaoming 《《地质学报》英文版》2011,85(3):656-660
In the present study, the modified Sverjensky–Molling equation, derived from a linear-free energy relationship, is used to predict the Gibbs free energies of formation of crystalline phases of α-MOOH (with a goethite structure) and α-M2O3 (with a hematite structure) from the known thermodynamic properties of the corresponding aqueous trivalent cations (M3+). The modified equation is expressed as ΔG0f,MVX=aMVXΔG0n,M3++bMVX+βMVXγM3+, where the coefficients aMVX, bMVX, and βMVX characterize a particular structural family of MvX (M is a trivalent cation [M3+] and X represents the remainder of the composition of solid); γ3+ is the ionic radius of trivalent cations (M3+); ΔG0f,MVX is the standard Gibbs free energy of formation of MvX; and ΔG0n,M3+ is the non-solvation energy of trivalent cations (M3+). By fitting the equation to the known experimental thermodynamic data, the coefficients for the goethite family (α-MOOH) are aMVX=0.8838, bMVX=?424.4431 (kcal/mol), and βMVX=115 (kcal/mol.?), while the coefficients for the hematite family (α-M2O3) are aMVX=1.7468, bMVX=?814.9573 (kcal/mol), and βMVX=278 (kcal/mol.?). The constrained relationship can be used to predict the standard Gibbs free energies of formation of crystalline phases and fictive phases (i.e. phases that are thermodynamically unstable and do not occur at standard conditions) within the isostructural families of goethite (α-MOOH) and hematite (α-M2O3) if the standard Gibbs free energies of formation of the trivalent cations are known. 相似文献
16.
本文系统地回顾了多相组分化学平衡的理论基础和计算方法，重点分析了当今流行的平衡常数法和自由能量小法的异同，证明了这些方法在原则上的同一性同时也证明了反应平衡常数和物种自由能之间的可互换怀，并指出了互换的方法。 相似文献
17.
Log–log correlation plots between the dissociation constants of known metal–chromate complexes and those of corresponding metal–sulfate complexes at 25 °C, 1 bar were used to derive the standard partial molal Gibbs free energies of formation of unknown metal–chromate complexes involving either (i) monovalent cations, divalent cations, and trivalent lanthanides or (ii) trivalent cations (excluding those of rare earth elements, REE) and tetravalent cations. For each of these two classes of ionic associations, empirical relationships between the standard partial molal volumes, isobaric heat capacities and entropies of known metal–chromate complexes and the corresponding thermodynamic properties of metal ions have been found. These data were utilized to evaluate the solute-characteristic parameters of the revised Helgeson–Kirkham–Flowers equation of state and to compute the thermodynamic properties of the dissociation reactions of metal–chromate complexes at high temperatures and pressures. 相似文献
18.
矿物在超临界溶液中的溶解度理论计算 总被引：10，自引：0，他引：10
本文概述了矿物在超临界溶液中的溶解度理论计算。讨论了平衡常数法和自由能法的热力学原理和计算机方法。两种方法都需要热力学数据,所不同的是平衡常数法需要的是反应平衡常数,而自由能法需要物种自由能数据。方法确定以后这些数据具备与否及其精度是这项研究的关键。此外当溶液中离子强度较大时,寻求一种适当的活度系数算法对溶解度理论计算也至关重要。 相似文献
19.
《地球科学进展》2015,30(12):1295
The interaction between ions and soil particles plays an important role in the mobilization and bioavailability of ions in soils, which is one of the main research areas of soil chemistry. The new method based on suspension Wien effect has been developed recently to determine the binding energy and adsorption energy between ions and soil particles. Compared with other methods on the basis of adsorption isotherm or ions activity, Wien effect method has more advantages including convenience and direct measurement. The term suspension Wien effect refers to the increase of electrical conductivity of suspension with increasing applied electrical field. In this review paper, we introduced the fundamentals of suspension Wien effect, the apparatus about the Wien effect measurement, and along with demonstrating their application to quantifying the particles-ions interactions for several systems of soils. Our studies indicated that divalent cations have larger binding energies and adsorption energies on soil particles than monovalent because of the electrostatic interaction. However, few studies about the interaction between Cr3+ and La3+ on soil particles showed that the binding energy and adsorption energy of trivalent cations are lower than those of divalent cations because of hydrolysis. Soil properties such as soil organic matter, soil pH, and iron oxides significantly affected the binding energy and adsorption energy of ions. Our results deepened our understanding about the non specific adsorption of ions in soil chemistry, and enlarged the research area of soil chemistry in fundamental and methodology. 相似文献
20.
R.L. Bassett 《Geochimica et cosmochimica acta》1980,44(8):1151-1160
Energy related industrial development, municipal waste treatment processes and some natural sources, contribute to B (being present) in the environment in elevated concentrations. Boron forms numerous aqueous ion pairs and complexes, some of which would not normally exist in significant concentrations under typical baseline environmental conditions. A complete understanding of the aqueous chemistry of B depends on an accurate evaluation of the thermodynamic data for these species.Equilibrium constants for 29 inorganic complexes, ion pairs, and polyanions of B have been critically evaluated. Apparent equilibrium constants have been extrapolated to zero ionic strength, and the selected thermodynamic values are tabulated. Gibbs free energies of formation for the aqueous species have been computed; these are presented with entropy and enthalpy values where available 相似文献