MgO—MgCl2—H2O溶液热化学研究

用精密量热仪对模拟合成的ＭｇＯ－２７．５６％ＭｇＣｌ－Ｈ２Ｏ浓盐溶液进行恒沸盐酸－△Ｈ滴定。发现活性ＭｇＯ在２７．５６％ＭｇＣｌ－Ｈ２Ｏ溶液中不同浓度时表现出不同的结果。结合该浓盐溶液的恒混盐酸－ＰＨ滴定结果对反应机制进行了初步探讨。     

MgO－B_2O_3－MgCl_2－H_2O体系与盐酸滴定反应的研究

ＭｇＯ－Ｂ２Ｏ３－ＨｇＣｌ２－Ｈ２Ｏ是含硼盐湖日晒浓缩盐卤的典型体系，它与盐酸反应生成硼酸，是从天然浓缩盐卤中制取硼酸的工艺基础，以量热滴定法和ｐＨ滴定法研究该反应，结果表明，析出硼酸的反应分两步进行；合成盐卤中硼酸盐可以用ＭｇＢ２ｎＯ（３ｎ＋１）（ｎ＝１，２，３）综合统计形式来表示；天然浓缩盐卤中硼酸盐可以用四硼酸镁的统计形式进行表示．     

2MgO·2B_2O_3·MgCl_2·14H_2O-H_3BO_3-H_2O体系30℃相平衡

用相平衡方法研究了2MgO·2B_2O_3·MgCl_2·14H_2O-H_3BO_3-H_2O在30 ℃ 不同浓度H_3BO_3水溶液中的溶解转化产物及其溶解度。结果表明，氯柱硼镁石的 溶解转化产物，在H_3BO_3质量分数≤2.50%时为多水硼镁石；在2.50% ～ 5. 00%H_3BO_3范围时为库水硼镁石；当H_3BO_3量在5.00% ～ 5.60%之间时为章氏硼 镁石；而当H_3BO_3量≥5.60%时为三方硼镁石。提出了溶解相转化机理。     

模拟合成盐卤与盐酸反应的热化学研究

青藏高原新类型盐湖卤水日晒蒸发过程中硼酸盐在浓缩卤水中富集L‘。，我们在前又问中曾报道天然浓缩盐卤中硼酸盐是以“四硼酸盐”的综合统计形式存在，当盐卤浓缩到氯化镁共饱和时，可视为MgO－BZO3－MgC12－HZO四元体系中的一个特定的膺三元体系MgO·2B2O3－MgC12－H。O．该四元体系20oC热力学非平衡态液固相图问与25oC热力学平衡态相图＊存在较大差别．由于聚合翻氧配阴离子的存在，使得对含棚浓缩盐卤的研究变得复杂而困难＊．李积才等“～SJ对合成盐卤的稀释热和表观摩尔热径进行过测定，李军间在对多种水合硼酸盐在盐酸中…     

盐卤硼酸盐化学 ⅩⅤ.2MgO·B_2O_3.MgCl_2·14H_2O和MgO.2B_2O_3·9H_2O的热化学研究

合成氯柱硼镁石(2MgO·2B_2O_3·MgCl_2·14H_2O)和章氏硼镁石(MgO·2B_2O_3·9H_2O),用恒定温度环境反应热量计测定溶解热和反应热的基础上,运用热化学循环原理计算得到这两种硼酸盐的标准生成焓。     

盐卤硼酸盐化学ⅩⅩⅥ．MgO·2B_2O_3－18％MgCl_2－H_2O产过饱和溶液结晶动力学研究

ＭｇＯ·２Ｂ２Ｏ３－１８％ＭｇＣｌ２－Ｈ２Ｏ过饱和溶液于２０℃恒温静置，其结晶过程分为两个阶段．第一阶段结晶析出三方硼镁石（ＭｇＯ·３Ｂ２Ｏ３·７．５Ｈ２Ｏ），第二阶段析出章氏硼镁石（ＭｇＯ·２Ｂ２Ｏ３·９Ｈ２Ｏ）．未得到多水硼镁石和库水硼镁石．探讨了两种析出团相的结晶机理并拟合出结晶动力学方程．结果表明，两种固相结晶机理均为多核表面反应控制生长．     

MgO－B2O3－MgCl2－H2O体系与盐酸滴定反应的研究

ＭｇＯ－Ｂ２Ｏ３－ＭｇＣｌ２－Ｈ２Ｏ是含硼盐湖日晒浓缩盐卤的典型体系，它与盐酸反应生成硼酸，是从天然浓缩盐卤中制取硼酸的工艺基础，以量热滴定法和ＰＨ滴定法研究该反应，结果表明，析出硼酸的反应分两步进行；合成盐卤中硼酸盐可用ＭｇＢ２ｎＯ３Ｎ＋１（ｎ＝１，２，３）综合统计形式来表示；天然浓缩盐卤中硼酸盐可以用四硼酸镁的统计形式进行表示。     

SrB_4O_7·3.5H_2O的合成、表征与热化学研究

合成了一种新型碱土金属硼酸盐SrB4O7·3.5H2O,并对它进行了化学分析、红外光谱(IR)、X射线衍射(XRD)及热分析(TG-DTA)等一系列物相鉴定与表征.通过设计热力学循环,利用微热量计测定了SrB4O7·3.5H2O溶解于约1 mol·L-1HCl水溶液中的摩尔溶解焓,再结合H3BO3在 HCl(aq)的摩尔溶解焓,Sr(OH)2·8H2O(s)溶解于[HCl(aq)+H3BO3(aq)]的摩尔溶解焓,以及H2O(l)、Sr(OH)2·8H2O(s)与 H3BO3(s)的标准摩尔生成焓,得到了SrB4O7·3.5H2O的标准摩尔生成焓为–(4435.15± 3.30)kJ·mol–1.     

盐卤硼酸盐化学 ⅩⅢ.2MgO·2B_2O_3·MgCl_2·14H_2O结晶动力学研究

对MgO-B_2O_3-MgCl_2-H_2O浓盐溶液结晶析出氯柱硼镁石(2MgO·2B_2O_3·MgCl_2·14H_2O)的动力学过程进行了研究。利用单纯形优化法配合Runge-Kutta微分方程组数值解法对实验数据进行处理,给出了结晶动力学方程。并对硼在溶液中的存在形式进行了讨论,提出了结晶反应机理,同时考察了温度和氯化镁浓度对结晶速率的影响。     

MgO·nB_2O_3-18%MgSO_4H_2O体系0℃时的热力学非平衡态液固相关系

在MgO·nB_2O_3-18%MgSO_4-H_2O体系0 ℃结晶过程的动力学研究、用物理方 法和化学分析确定析出固相的组成和测定固相共饱和点的基础上，给出了该体系0 ℃时的热力学非平衡态液固相关系图。该相图存在四个相区，分别与H_3BO_3， MgO·3B_2O_3·7.5H_2O，MgO·2B_2O_3·9H_2O和2MgO·3B_2O_3·15H_2O（多水 硼镁石）相对应。结果表明MgCl_2和MgSO_4介质对镁硼酸盐的析出有不同的影响。     

A Study on the Dissolution of Ferric Oxide in Aqueous Hydrochloric Acid Solutions

The effect of hydrochloric acid concentration and the effect of temperature on the rate of dissolution of Fe₂O³ have been investigated. Being heterogeneous, the dissolution reaction has been characterized to have an apparent activation energy of 21.5 Kcal/mol for a 7.11 m aqueous hydrochloric acid solution at temperatures between 273 and 373°K. The rate is linearly correlated to the mean activity of hydrochloric acid in the range from 1.3 to 10.8 m at 300°K.     

盐酸和氯化钙混合溶液中滴加碳酸钠溶液pH变化的实验探究*

盐酸、氯化钙混合溶液中滴加碳酸钠溶液,当碳酸钙沉淀出现后,混合溶液pH是否基本不变？此时的pH是否为7？为此用数字化实验对盐酸、氯化钙混合溶液中滴加碳酸钠溶液pH的变化进行了探讨,对平台段的出现及平台段溶液pH进行了实验探究和理论分析。     

Spectrophotometric Determination of Carboxylic acids with 2-Mitrophenylhydrazine in Aqueous Solution

Abstract

Carboxylic acids were determined spectrophotometrically by converting them into 2-nitrophenylhydrazides. The coupling reaction of carboxylic acids with 2-nitrophenylhydrazine was effected by a water-soluble carbociimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, and proceeded efficiently in aqueous solution buffered at pH 4.5 with pyridine and hydrochloric acid. The yields of hydrazides from acetic and benzoic acids were nearly quantitative. The reaction mixture was then made strongly alkaline, and after heating to reduce the blank absorbance, the absorbance of the hydrazide was measured at around 540 nm. Calibration curves of various carboxylic acids were linear between 0.02 and 0.5 μmol through the origin.     

Mg(BO2)2在MgCl2水溶液中的相平衡与化学平衡

借助拉曼光谱和X射线衍射(XRD)检测手段,对Mg(BO_2)_2在MgCl_2水溶液中水解的固液相平衡与物种化学平衡规律进行了研究。结果表明,MgCl_2对Mg(BO_2)_2的溶解转化、多硼氧配阴离子的物种分布有很大影响:(1)随着MgCl_2浓度从0达到饱和,Mg(BO_2)_2的表观饱和浓度从0.79%增加到1.96%,pH值从9.96降到6.27;(2)Mg(BO_2)_2在纯水中水解形成固相Mg_2B_6O_(11)·15H_2O和Mg(OH)_2,在MgCl_2溶液中形成固相Mg_2B_6O_(11)·15H_2O和Mg_3Cl_2(OH)_4·4H_2O;(3)Mg(BO_2)_2在纯水中水解,硼的物种主要为B_4O_5(OH)_4~(2-)和B_3O_3(OH)_4~-,分别占液相总硼含量的49.81%和19.54%。在MgCl_2饱和溶液中,主要为B_3O_3(OH)_4~-和B_5O_6OH)_4~-,分别占液相总硼含量的44.57%和40.00%。     

Structure of classical fluid of charged hard spheres and point lons in the perturbation of a small non-responsive,uniform background density

Abstract

In liquid Te, the model of Cabane and Friedel is based on the coexistence of a network of strong covalent bonds with a metallic-like electron gas. We have attempted to simulate the gross features of this situation by studying a classical fluid of charged hard spheres, plus point charges (classical electrons!), all moving in a small neutralizing negative background density.

An exact solution of even this model will require computer simulation. We have therefore worked in the approximation of the mean spherical model. Also, we treat the neutralizing background only to first order in the background density.

The main effect of the background is to increase the height of the contact value of g(r) for the hard sphere pair correlations. This appears to correspond qualitatively with the high temperature behaviour of liquid Te.     

Densities and apparent molal volumes of aqueous CaCl2 and MgCl2 solutions

The Pitzer ion interaction model has been used to evaluate literature data for the densities of aqueous CaCl₂ and MgCl₂ solutions between 0 and 100°C. The selected data can be adequately fitted by setting ^(1),v equal to zero. The variations of ^(0),v and C ^v with temperature have been found to be linearly correlated. The uncertainty in the calculated density is lower than 50 ppm below 1M but raises to 300 ppm at high concentrations. When plotted vs. the square root of the molality, the apparent molal volume of MgCl₂ shows a change at a concentration where a transition in the speed of sound has already been reported by Millero, et al.     

Thermodynamics of the GaCl3-HCl-H2O System at 25°C

A comprehensive equation for the thermodynamic properties of the systemGaCl₃-HCl-H₂O at 25°C in the ion-interaction (Pitzer) equation form has been generatedon the basis of a recent and comprehensive array of electrochemical cellmeasurements of the HCl activity at total stoichiometric ionic strengths from 0.01 to 3.0mol-kg^–1. Alternate equations with and without explicit consideration of thehydrolyzed product GaOH²⁺ as a separate species have been tested. Excellentagreement is obtained between the calculated and measured cell potentials forthe formulation, which includes GaOH²⁺ as an additional species. The effect offurther hydrolysis as well as that of complex formation has been found to benegligible. While a satisfactory set of Pitzer parameters has been found, it wasnot possible to obtain a unique thermodynamic representation for this systembecause of large uncertainties in the first hydrolysis constant of Ga(III) and becauseof redundancies and intrinsic correlations between some of the Pitzer parameters.Deceased December 26, 1997     

手性纳米磷酸锌钠的热化学研究

Chirai sodium zincophosphate nanocrystalline has been prepared and characterized. The standard molar enthaipy of the following reaction 12Na3PO4·12H2O（s）＋ 12ZnSO4·7H2O（s）= Na12（Zn12P12O48）·12H2O（s）＋ 12Na2SO4（s）＋216H2O（1） was determined by solution reaction calorimetric at 298.15 K, and calculated to be 33.666±0.195 kl/mol. From the results and other auxiliary quantities, the standard enthalpy of formation for sodium zincophosphate nanocrystalline was derived to be △fHm^⊙ [Na12（Zn12P12O48）·12H2O（s）, 298.15 K] =- 24268.494 ± 0.815 kJ/mol.     

Complexation of Some Amino Acids and Peptides by p-Sulfonatocalix[4]arene and Hexasodium p-Sulfonatocalix[6]arene in Aqueous Solution

The stability constants (log K), the reaction enthalpy( H) and entropy ( S) of the complexesformed between some amino acids (glycine, L-alanine,L-valine, L-leucine, L-phenylalanine, L-tryptophan,L-threonine, and L-lysine) and peptides (glycyl-glycine,glycyl-L-alanine, glycyl-L-leucine, glycyl-L-phenylalanine,L-leucyl-glycine, L-leucyl-L-alanine, glycyl-L-valine,L-leucyl-glycyl-glycine, and glycyl-glycyl-glycine) withp-sulfonatocalix[4]arene and hexasodiump-sulfonatocalix[6]arene in aqueous solutions by meansof calorimetric titration have been investigated. The reportedresults demonstrate that the amino acids and peptides under studyform complexes with both p-sulfonatocalix[4]areneand hexasodium p-sulfonatocalix[6]arene. In the case of theamino acids and peptides the complexation with water-solublecalixarenes in aqueous solution is favored by enthalpiccontributions and disfavored by entropic contributions. However,no influence of the ring size of the calixarenes upon thecomplexation is observed. By comparison with the reaction ofthe sodium salt of phenol-4-sulfonic acid with amino acids amacrocyclic effect in case of the calixarenes is possible.