双室型沸点升高仪

任何非挥发性溶质溶于溶剂后,都能使溶剂的蒸气压下降,因此溶液的沸点必然高于纯溶剂。如果溶液浓度很小,同时又无电离或缔合现象发生,则溶液的沸点升高与浓度成正比。应用理想溶液定律,可以推导出: △T_b=1000×K_b/M_2×W_2/W_1 (1)式中△T_b为沸点升高值,W_1为溶剂的克数,W_2为溶质的克数,M_2为溶质的分子量,K_b为溶剂的沸点升高常数,是一个决定于溶剂而与溶质无关的数值。为此,如能测出溶液的沸点升高,即可求出溶质的分子量。这个方法原理十分简单,是物理化学中测定分子量的经典方法之一。但是,由于实验精确度的限制,直到五十年代初,还只限于用来测量分子量约为几千的     

熔封过程对挥发性有机物溶液标准物质的量值影响研究

本文研究了挥发性有机物溶液标准物质在熔封过程中影响量值稳定的主要因素以及对定值结果的不确定度贡献。通过实验考察溶质沸点在-13.4℃至220℃的7种挥发性有机物溶液标准物质在不同条件下熔封,使用外标法准确测定熔封前后溶液的量值变化。研究结果表明,以甲醇为溶剂,溶质沸点在-13.4℃至80℃范围内的挥发性有机物溶液的最佳冷却温度为-20℃,溶质沸点在80℃至220℃范围内溶液的冷却温度相对较高。溶质沸点越低,对挥发性有机物溶液的分液方式要求越高,全密闭管路的分液方式最佳。在安瓿瓶熔封过程中使用冷却套管,可以有效的减少火焰热效应对溶液的影响。对实验考察的7种挥发性有机物溶液标准物质的不确定度可降低至1%以内。     

氯化丁基橡胶/聚(甲基)丙烯酸酯共混物阻尼性能研究

制备了一系列氯化丁基橡胶 (CIIR) 聚 (甲基 )丙烯酸酯 (PMAc)共混复合物 .DMA ,DSC对这些共混物的研究表明 ,无论是共交联体系还是非共交联体系 ,CIIR PMAc共混物均能将CIIR有效阻尼功能区移向高温 ;FTIR分析及抽提实验证明了前一体系CIIR PMAc共混物中共交联结构的存在 ;TEM研究发现 ,共交联改变了CIIR PMAc共混物的微观形貌 .研究结果表明 ,不同组成和结构的PMAc的引入 ,导致共混物中CIIR的Tll转变和Tg 转变受到不同程度的抑制 ,因此引起由共交联体系和非共交联体系制得的CIIR PMAc共混物显示出不同的阻尼行为 .     

冰点下降法测定分子量

非挥发性溶质(具有极低的蒸气压)溶于溶剂后,能降低溶剂的蒸气压,同时引起沸点的升高和冰点的下降。     

克拉珀龙方程、拉乌耳定律及非挥发性稀溶液沸点升高公式之间的关系

本刊1961年第11期“问题讨论”栏刊登了蔡寿辉同志写的“非挥发性溶质稀薄溶液的沸点上升和冰点下降的热力学”一文,他把克拉珀龙方程式、拉乌耳定律及沸点升高公式统一于多相平衡的一般原理来推导,同时获得了这三条定律的偏微分表达式,我们认为这样处理明确了所得到的三个定律之间的横的关系,这有助于认识它们之间的差异性,从而掌握各定律适用的条件。此外,他对克拉珀龙方程式用之于稀溶液的近似性的讨论也是有益的。但是对于这三个定律之间纵的关系,该文没有进     

从拉乌尔定律和亨利定律看恒沸溶液

气液平衡是理论教学和实际生产中的重要内容。本文从微观本质讨论理论教学中的拉乌尔定律和亨利定律以及实际生产中的恒沸溶液之间的关系和区别。溶剂-溶剂、溶剂-溶质和溶质-溶质之间相互作用的不同导致两个定律仅适用于稀溶液。这些相互作用通过物质的量分数调节溶剂和溶质的表观蒸气压,当二者的表观蒸气压相等时,则产生了恒沸溶液。     

电热原子吸收光谱分析中的干扰及其消除和控制(二)

4.溶质挥发干扰与光谱干扰不同,非光谱干扰通过改变在电热原子化器中产生的含时原子浓度直接影响待测物信号。溶质挥发干扰或凝相干扰在待测元素从原子化器表面释放到气相中之前影响待测元素,而气相干扰则影响其后的任何平衡过程。必须考虑的炉过程远比引起光谱干扰的过程复杂,并且我们在这方面知识有限,使     

膜蒸馏分离甲酸-水共沸混合物

共沸混合物的分离通常是采用共沸蒸馏或萃取蒸馏来进行。本文研究了用膜蒸馏技术来分离甲酸-水共沸混合物的可能性。结果表明,采用膜蒸馏来处理甲酸-水溶液时不存在共沸现象。表明膜蒸馏在分离共沸物方面具有潜在的应用价值。     

非等度毛细管色谱条件下溶质半高宽规律的实验研究

]本文基于对大量实验数据的分析,提出一个描述同组分在非等度色谱条件下半高宽变化规律的实验模型。将一系列溶质用在两个不同毛细管色谱柱上检验了其可靠性。已经证实,溶质半高宽的实验值与计算值之间的最大相对偏差不超过22,多数情况不大于15％     

利用红外振动光谱研究甲醇-乙酸甲酯共沸体系的微观结构

红外振动光谱是测量物质分子结构和鉴别化合物组成的分析方法,在科研和工业分析领域广泛应用。通过红外吸收峰强度和位置变化研究体系组成及微观结构,并进一步推测其动力学信息。随着技术不断发展,红外振动光谱测量仪器也逐渐小型化、简便化,然而红外光谱实验在本科物理化学实验中未涉及。基于此并为贯彻科教融合理念,作者尝试将大学生创新创业训练计划项目“利用离子液体作为夹带剂分离共沸物的动力学研究”拓展为本科生物理化学实验,以填补红外光谱测量方法在大学物理化学实验课学习中的空白。本文选取甲醇-乙酸甲酯共沸体系为研究对象,其在聚乙烯醇工业中具有重要的研究价值。此外,共沸体系在物理化学热力学相平衡的学习中也十分重要,但学生对其微观结构缺乏直观的认识。因此利用红外振动光谱研究共沸体系的微观结构在物理化学教学和实验中具有重要的意义。     

汽液平衡盐效应中的沸点变化(英文)

测定了在恒压(100.0kPa)条件下若干含盐双液系(甲醇-水,乙醇-水,正丙醇-水)的沸点变化.实验结果表明引起溶液沸点降低 反常现象"发生的必要条件是易挥发组分被盐析或难挥发组分被盐溶.经热力学分析表明上述实验结果是一个具有普遍意义的结论.     

Effect of nonvolatile solute on vapor–liquid equilibrium at fixed liquid composition

The influence of some nonvolatile solutes on boiling points of two azeotropic mixtures (1-propanol–water and methanol–tetrahydrofuran systems) was determined by means of isobaric vapor–liquid equilibrium experiments. A basic thermodynamic equation of nonvolatile solute effect on vapor–liquid equilibrium at fixed liquid composition was derived. Based on the theoretical analysis about the equation, two criterions of universal significance were obtained: (1) when a little nonvolatile solute dissolves in a binary liquid mixture with constant composition, if the vapor composition of less volatile component is increased the boiling point must be elevated at given pressure or the vapor pressure must be depressed at given temperature; (2) when a little nonvolatile solute dissolves in an azeotropic mixture, any kind of nonvolatile solute always causes the elevation of boiling point at given pressure or the depression of vapor pressure at given temperature irrespective of the variation of vapor composition. Verifying through the experiments of this paper and lot of the relevant experimental data in the literature, all of the experimental results were in agreement with both criterions without exception.     

Correlation Equations for Predicting the Temperature Depression in Boiling of Aqueous Solutions of Nonvolatile Substances

Three-constant correlation equations describing the boiling point of aqueous solutions of non-volatile substances and temperature depression in boiling of the solutions under normal and arbitrary pressures are considered. The three constants appearing in the correlation equations are tabulated for aqueous solutions of 19 nonvolatile substances, and formulas for determining these constants for other aqueous solutions of nonvolatile substances from experimental data are presented.     

Henry’s law constant for environmentally significant compounds

Many nonvolatile organic compounds, e.g., polyaromatic hydrocarbons (PAHs), are readily stripped during aerobic biodegradation. This is because of the high infinite dilution activity coefficient resulting from forces generated by the water-organic interactions at the molecular level. Several models have been proposed for air-stripping based on the Henry’s law constant. By definition, the Henry’s law constant is the infinite dilution activity coefficient multiplied by the pure component vapor pressure. In this article, a gas saturation technique was used to measure the very low vapor pressures exhibited by these nonvolatile compounds. Literature values of other PAHs have been tabulated and are presented. For determining infinite dilution activity coefficients, a differential ebulliometery apparatus has been constructed. In this technique, the boiling point difference between pure water and a water-organic solution is measured very precisely. Thermodynamics is then used to calculate the infinite dilution activity coefficient. The method’s accuracy has been tested using the phenol-water system.     

Predicting the Normal Temperature Depression in Boiling of Complex Aqueous Solutions of Nonvolatile Substances

An equation for predicting the normal temperature depression in boiling of complex aqueous solutions of nonvolatile substances is considered. The constants of the equation are tabulated. The equation is compared with experimental data for a binary solution of caustic soda and sodium chloride.     

垃圾焚烧炉飞灰熔融特性及重金属的分布

对垃圾焚烧炉飞灰进行了差热分析及熔融实验,探讨了不同熔融温度对试样的灼烧减量及重金属分布特性的影响。结果表明,飞灰试样在1132℃时熔融,在1252℃～1290℃发生二次熔融。灼烧减量在1200℃达到最低值27.5％; Cr、Ni、Cu在熔融体中的固溶率随着沸点的升高而依次升高。重金属Pb、Cd、As、Hg挥发率均超过95％,挥发性依次为Pb>Cd>As>Hg;飞灰中Zn的氧化物熔融后转化为Zn2SiO4、ZnSiO3和ZnAl2O4等不易挥发的化合物,且Zn在1200℃时挥发率最低仅有66.7％。     

Boiling Point of Tetraethyllead

In view of the pronounced inconsistency of published data on the boiling point of tetraethyllead, its value was determined by several independent calculation procedures. Simultaneously, data on the molar volume of liquid tetraethyllead at the boiling point, lacking in the literature, were obtained.     

Size‐exclusion chromatography for the determination of the boiling point distribution of high‐boiling petroleum fractions

The paper describes a new procedure for the determination of boiling point distribution of high‐boiling petroleum fractions using size‐exclusion chromatography with refractive index detection. Thus far, the determination of boiling range distribution by chromatography has been accomplished using simulated distillation with gas chromatography with flame ionization detection. This study revealed that in spite of substantial differences in the separation mechanism and the detection mode, the size‐exclusion chromatography technique yields similar results for the determination of boiling point distribution compared with simulated distillation and novel empty column gas chromatography. The developed procedure using size‐exclusion chromatography has a substantial applicability, especially for the determination of exact final boiling point values for high‐boiling mixtures, for which a standard high‐temperature simulated distillation would have to be used. In this case, the precision of final boiling point determination is low due to the high final temperatures of the gas chromatograph oven and an insufficient thermal stability of both the gas chromatography stationary phase and the sample. Additionally, the use of high‐performance liquid chromatography detectors more sensitive than refractive index detection allows a lower detection limit for high‐molar‐mass aromatic compounds, and thus increases the sensitivity of final boiling point determination.     

Boiling points of halogenated ethanes: an explanatory model implicating weak intermolecular hydrogen-halogen bonding

This study explores via structural clues the influence of weak intermolecular hydrogen-halogen bonds on the boiling point of halogenated ethanes. The plot of boiling points of 86 halogenated ethanes versus the molar refraction (linked to polarizability) reveals a series of straight lines, each corresponding to one of nine possible arrangements of hydrogen and halogen atoms on the two-carbon skeleton. A multiple linear regression model of the boiling points could be designed based on molar refraction and subgroup structure as independent variables (R(2) = 0.995, standard error of boiling point 4.2 degrees C). The model is discussed in view of the fact that molar refraction can account for approximately 83.0% of the observed variation in boiling point, while 16.5% could be ascribed to weak C-X...H-C intermolecular interactions. The difference in the observed boiling point of molecules having similar molar refraction values but differing in hydrogen-halogen intermolecular bonds can reach as much as 90 degrees C.     

药厂废液中有机酸的分离分析

利用减压蒸溜法分离废液中的低沸点有机酸,结合红外光谱、气相色谱、质谱,确定了废液中以乙酸、丙酸为主的10种有机酸的结构,其含量占分析废液的2.64%。其中丙酸含量最高,其次为乙酸。同时被检测到的还有乙醇,乙醛等。另外通过柱层析分离高级脂肪酸,并进行衍生化处理,经GC、GC-MS检测,确定了四种高沸点有机酸的结构,含量为1.71%。9,12-十八二烯酸含量相对较高。因此有机酸占废液总量的质量分数为4.35%。