等浓度碳酸氢钠和醋酸钠2种溶液的pH大小比较

利用Excel对相同浓度的NaHCO3溶液、CH3COONa溶液中离子浓度的精确计算,得出相同浓度的2溶液中,水解程度一定是HCO3->CH3COO-,但不能仅通过水解程度大小来得出pH(NaHCO3溶液)>pH(CH3COONa溶液)的结论,2溶液的pH大小还与溶液浓度有关。     

P(AMPS-co-BMA)水凝胶的电场敏感性及电刺激响应机理

以离子型单体2-丙烯酰胺-2-甲基丙磺酸(AMPS)及非离子型单体甲基丙烯酸丁酯为原料, 偶氮二异丁腈为引发剂, N,N′-亚甲基双丙烯酰胺为交联剂, N,N-二甲基甲酰胺为溶剂, 通过自由基聚合合成了一系列聚离子浓度不同的聚(2-丙烯酰胺-2-甲基丙磺酸-co-甲基丙烯酸丁酯)电场敏感性水凝胶. 研究了其在去离子水及NaCl溶液中的溶胀行为. 结果表明, 该水凝胶在去离子水中的平衡溶胀度在236.4~298.5之间, 其溶胀速率随着AMPS用量的增加而增加; 并且随着凝胶内部聚离子浓度的增加, 凝胶在NaCl溶液中的消溶胀速率及消溶胀度逐渐减小. 凝胶的电刺激响应性能研究结果表明, 在电场存在下, 凝胶在NaCl溶液中的溶胀行为与凝胶内部聚离子浓度和溶液中NaCl浓度的相对大小有关, 当凝胶内部聚离子浓度大于溶液中NaCl浓度时, 凝胶溶胀, 反之则凝胶消溶胀; 而且, 凝胶在电场作用下的偏转行为同样与凝胶内部聚离子浓度和溶液中NaCl浓度的相对大小有关, 当凝胶内部聚离子浓度大于溶液中NaCl浓度时, 偏向阴极, 反之则凝胶偏向阳极. 另外, 在电场存在下, 凝胶在NaCl溶液中的电偏转速度与环境温度密切相关.     

一元弱酸(碱)溶液稀释过程中离子浓度递变幅度的相对非均等性

对一元弱酸（碱）溶液稀释过程中各种离子浓度递变幅度的相对非均等进行研究,推出了离子浓度递变幅度的大小次序排列及其相关概念,这一研究,有助于从整体上把握离子浓度递变规律,为正确判断离子浓度的变化结果提供了理论依据。     

FTIR和ESR法研究离聚体溶液中的离子相互作用

磺化乙丙三元共聚物(SEPDM)离聚体在二甲苯/5％正己醇混合溶剂中具有特异的粘浓关系和粘温关系,估计是由于金属离子被己醇溶剂化而影响离子间相互作用引起的,但尚未有更多的实验数据加以验证.本文用FTIR和ESR方法对SEPDM离聚体溶液作进一步考察,发现金属离子与己醇确实存在溶剂化效应,溶剂化程度与离子的大小、浓度和温度有关,它直接影响离子在溶液中存在的状态(单离子或离子聚集体),这些结果为从分子水平了解离聚体溶液性质提供了理论根据.用波谱方法研究离聚体溶液中的离子相互作用尚鲜见报道.     

1-1型单组分盐溶液中荷电膜膜电位的研究

根据固定电荷模型和非线性最小二乘法, 研究膜体积电荷密度为定值和其大小随电解质主体溶液浓度呈指数变化的两种初始条件下, 五种纳滤膜(NTR 7450, ESNA 1, ESNA 1-LF, LES 90和UTC 60)在不同浓度的氯化钠和氯化钾溶液中的膜电位, 获得膜体积电荷密度与电解质主体溶液浓度的关系. 结果表明, 当体积电荷密度随浓度呈指数变化时, 拟合的膜电位与实验结果更接近, 得到的固定电荷密度更精确. 膜电位的大小与膜两侧电解质溶液浓度的比值相关. 在较高浓度时, 膜电位的值还与扩散系数相关; 其中阴阳离子的扩散系数之比大于1.0是膜电位反号的标志. 在中间浓度时, 膜电位随电解质主体溶液浓度近似呈线性变化.     

硫酸根离子对铁在弱碱性溶液中阳极溶解和钝化行为的影响

采用浸泡实验, 电化学测试和表面分析技术研究了硫酸根离子浓度对铁在稀碳酸氢钠溶液中开路状态和阳极极化行为的影响. 在无硫酸根离子及含有少量硫酸根离子的碳酸氢钠溶液中, 铁的开路电位约为(-0.225±0.005) V, 并呈现钝化状态, 其电化学阻抗很大, 腐蚀速率较低. 在含有较高浓度硫酸根离子的碳酸氢钠溶液中, 铁的开路电位为(-0.790±0.010) V并呈现活性溶解状态, 其电化学阻抗较小, 腐蚀速率较高, 同时阳极极化曲线上能观察到活化-钝化转变现象. 由于铁在含有较高浓度硫酸根离子的碳酸氢钠溶液中处于活化状态, 阳极极化曲线上存在数个电流峰. 足够高的硫酸根离子浓度会导致铁表面预先形成或转变而成的氧化膜失效. 相比于自然曝氧状态, 在除氧条件下较低的硫酸根离子浓度即可引起铁在碳酸氢钠溶液中由钝态向活性溶解态的转变.     

Hittorf法测定离子迁移数实验的改进

以不同浓度的CuSO4溶液为电解质,Pt电极和Cu电极分别为电解电极,通过观察通电前后电解质溶液阳极区和阴极区颜色的变化,定性分析离子的电迁移现象.通过电极上产生/溶解Cu的变化量以及CuSO4溶液浓度的变化,计算了不同浓度CuSO4溶液中离子的迁移数,并对浓度等因素对迁移数的影响规律进行了探讨.本文对传统离子迁移数的实验进行了改进,旨在加深学生对离子电迁移现象的认识及对迁移数概念的理解.     

究竟何种答案正确?

浙江大学分析化学教研组编“分析化学习题集”有这么一道例题:“于0.001mol·dm~(-3)的F~-离子溶液中,放入F~-离子选择电极与另一参比电极,测得的电动势为0.158V,于同样的电池中,放入未知浓度的F~-离子溶液,测得的电动势为0.217V。两份溶液离子强度一致。计算未知溶液中F~-离子的浓度。”这是一道离子选择性电极标准校正法例题,我认为例题不够     

高浓度LiClO4/丙酮溶液中离子-溶剂和离子-离子的相互作用

利用红外和拉曼光谱技术研究了不同浓度LiClO₄/丙酮溶液中离子-溶剂和离子-离子的相互作用. 红外和拉曼光谱的分析表明, Li^＋与丙酮分子发生了强烈的相互作用, 导致丙酮C—C伸缩振动谱带、C＝O伸缩振动谱带等发生了分裂. Li^＋的溶剂化数随溶液浓度的增加逐渐降低, 在所研究的LiClO₄浓度范围(0.31～3.98 mol•kg^－1)内由3.4减小到1.9. 此外, 根据的谱带变化确定了溶液中存在的多种离子对的形式, 计算了缔合平衡常数, 并与电导实验结果进行了比较, 解释了这两种方法测定的离子缔合常数存在差异的主要原因.     

高浓度LiClO4/丙酮溶液中离子-溶剂和离子-离子的相互作用

利用红外和拉曼光谱技术研究了不同浓度LiClO₄/丙酮溶液中离子-溶剂和离子-离子的相互作用. 红外和拉曼光谱的分析表明, Li^＋与丙酮分子发生了强烈的相互作用, 导致丙酮C—C伸缩振动谱带、C＝O伸缩振动谱带等发生了分裂. Li^＋的溶剂化数随溶液浓度的增加逐渐降低, 在所研究的LiClO₄浓度范围(0.31～3.98 mol•kg^－1)内由3.4减小到1.9. 此外, 根据的谱带变化确定了溶液中存在的多种离子对的形式, 计算了缔合平衡常数, 并与电导实验结果进行了比较, 解释了这两种方法测定的离子缔合常数存在差异的主要原因.     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。