新型三通道渗透管装置的研制

介绍了自行设计和研制的新型三通道渗透管装置。利用计算机控制和监测渗透池温度、气体流量以及混合气浓度等参数,利用采集的数据可对装置的稳定性进行评价。对装置进行了分流设计,以确保不同通道的气体能够快速混合均匀。该装置可以实现在保证输出混合气流量不变的情况下,快速改变不同通道混合气的摩尔分数,从而达到校准仪器的目的。     

简易电解水装置

一、装置的制作选一个管壁较厚的U形管,把U形管的管口用胶塞塞紧,把喷灯的火焰调成小火,然后将U形管弯曲处的中心部位放在火焰上加热,待玻璃红软后,U形管中气体膨胀使红软处吹开一个小孔,将小孔和预先准备的细玻璃管放在喷灯上加热至红软,然后迅速对接。     

检验气体性质的简单装置

实验装置用一段外径为1.1厘米的硬质玻璃管在喷灯上弯曲并吹制成如图1的“双球U形管”（简称U形管）。将U形管装配在双孔橡胶或软木塞上,其中一个孔安装一个小分液漏斗。实验时将塞装配在100毫升园底烧瓶上（见图2）。     

用滤纸片作隔膜改进胶体电泳实验

用最大号的打孔器将厚滤纸打成圆片（直径比U形管内径稍稍大一点点）,然后将滤纸片（单层或双层都可）斜着插入管内Fe(OH)3胶体液面以下。再用比U形管稍细一点的玻璃管将滤纸片压平并卡在管中。注意要使两管中的滤纸片在同一水平线上,并且纸下不要有气泡,装置如左下图。     

实验改进二则

钠和水反应实验的改进 1.装置 （见右图） （1）、取一支废旧的U形管,在U形管一侧,距弯曲部位30毫米处截断。 （2）、把用铝箔包好的一小块钠穿在大头针上,将针尖插在装有玻璃尖咀和止水夹的橡皮塞上。然后按图组装即可使用。     

微型电解水装置与燃料电池的改进

将V形管和下部带支管的U形管改装成电解水的实验装置和燃料电池具有操作简便、现象明显、节时省药、避免手指接触有腐蚀性的电解液等优点。用2B铅笔芯做电极,插入盛有适宜电解质溶液的V形管,电解片刻即可成为使音乐闪灯贺卡响亮数分钟的燃料电池。     

熔融的电解质导电实验改进

初中化学课本P.169[实验5--2]熔化的硝酸钾导电实验很不直观,教参及化学刊物介绍用U形管代替瓷坩埚,但受热面积宽,加热时间长,U形管一般加热易炸裂。我作了如下改进,效果很好。     

迁移管形状对希托夫法测定离子迁移数结果的影响

在希托夫法测定Cu~(2+)离子迁移数的物理化学实验教学中,目前常用直形和U形两种类型的迁移管,其中使用U形迁移管从阴极区溶液浓度变化算出的迁移数误差较大。以CuSO_4为电解质,Cu电极为电解电极,采用分光光度法分别测定了通电后直形、U形和n形三种迁移管中CuSO_4溶液浓度随高度的分布情况。研究发现,迁移管的形状对中部区溶液的浓度有较大影响。对于U形和n形迁移管,由于阴极位于迁移管底部,主要受重力作用引起的对流因素的影响,通电后中部区浓度会发生明显改变,并影响到阴极区溶液浓度,导致误差较大;使用直形迁移管受该因素的影响很小,能得到更为准确的结果。     

介绍一种微型实验装置

取一直径1cm的T型管,将两边直管利用酒精喷灯烧熔弯曲成锚形管,如图所示。将一不带乳胶头的滴管插入中间竖管。取5号废电池的碳棒两根分别插入锚形管的两边。利用该装置可做下面的实验。     

关於“离子运动”的一些演示实驗

(甲)电源:用220伏特交流电,通过0.5％NaHCO_3溶液整流器变成直流电;整流器裝置見右圖。 (乙)装置:將要实驗的电解質,配成有顏色的水溶液,如碱溶液可滴入几滴酚酞酒精溶液,变成紅色。酸溶液可滴甲基橙酒精水溶液,变成橘紅色。有色的溶液不必另加色。將配好的溶液,盛入U形玻管,从管底起到液面垂直高     

Osmotic compression of mixtures of polymers and particles

Aqueous dispersions of nanometric ceria particles have been concentrated through osmotic stress. Mixed dispersions of ceria with small adsorbing macromolecules of poly (vinylpyrrolidone) have been prepared by the same method. The osmotic pressure of pure ceria dispersions results from electrostatic repulsions between particles. The osmotic pressure of dispersions containing a non-saturating amount of PVP is the same as that of pure dispersions, and the colloidal stability is depressed with respect to the pure dispersions. The osmotic pressure of dispersions containing an excess of PVP is increased by the free macromolecules, and the colloidal stability is enhanced. The organization of particles in these dispersions has been examined by small-angle x-ray scattering and cryotransmission electron microscopy. In pure ceria dispersions and in saturated dispersions, a liquid-like short-range order was found; when the concentration is increased, this short-range order follows a three-dimensional swelling law. In dispersions containing a non-saturating amount of PVP, the structure shows an alternance of clusters and voids, and the separations of clusters follow an unusual one-dimensional swelling law.     

Calculation of the osmotic and activity coefficients of seawater at 25°C

The equation of Reilly, Wood, and Robinson was used to predict the osmotic coefficient of seawater and of its concentrates at molal ionic strengths of 0.5 to 6.0 at 25°C. The results agree closely with experimental data at ionic strengths below 5. The average difference in osmotic coefficients over the entire concentration range is 0.0014. The only serious discrepancy is at an ionic strength of 6, where a difference of 0.0068 is found. The accuracy of the predictions of osmotic coefficients prompted the calculation of the activity coefficients of NaCl, Na₂SO₄, MgCl₂, MgSO₄, KCl, and K₂SO₄ in the mixture. The calculated activity coefficients of NaCl and Na₂SO₄ agree within experimental error with previous measurements. This agreement demonstrates the prediction of activity and osmotic coefficients for complex mixtures.     

为什么要引入溶剂的渗透因子

阐明了引入溶剂渗透因子的必要性,较详细地介绍了两种渗透因子及它们间的关系。     

渗透压法对牛血清蛋白在NaCl水溶液中相互作用的研究

测量了牛血清蛋白不同pH值和不同离子强度Nacl水溶液中的渗透压,计算了渗透第二维里系数,按照Prausnitz提出的分子热学模型计算了蛋白质之间的静电排斥能、色散吸引能和离子排斥体积产生的吸引势能,并对这三种势能与溶液pH值和离子强度的变化关系进行讨论。     

Osmotic coefficients of vinylic polyelectrolyte solutions without added salt

 The osmotic pressures of –polyelectrolyte solutions without added salt was measured in the concentration ranges 0.001–0.02 and 0.2–1.9 mol kg^-1. Our results show that the osmotic coefficients φ_p were strongly dependent on the chemical structures of polyelectrolyte through the polyion radius and the interaction between the ionic moiety and counterions. The osmotic pressures in polyelectrolyte solutions without added salt, calculated on the basis of the counterion contribution, are in agreement with the experimental results. We conclude that the counterion contribution is dominant in the osmotic pressures and thus, the polymer contribution is negligible in the examined concentration range 0.2–1.9 mol kg^-1. The P–B approach gave a fair prediction of the absolute values of the osmotic pressures with λ=4.5, where λ is the charge density parameter, except for NaPA. In other words, the concentration dependence of the φ_p values can be explained in terms of the counterion contribution. Received: 11 June 1997 Accepted: 19 August 1997     

广义渗透系数

本文将Bjerrum渗透系数概念推广到混合溶剂体系中,提出了广义渗透系数的概念及其一般定义式,并导出了广义渗透系数与电解质活度系数之间的相互关系式,从而可以借助于广义渗透系数较易实现混合溶剂体系中溶质与溶剂热力学性质之间的相互推算,同时,混合溶剂作为一个整体的非理想性亦可得到具体度量.因此引入广义渗透系数概念具有理论与实际意义.     

Freestanding polyelectrolyte films as sensors for osmotic pressure.

Freestanding ultrathin polyelectrolyte-multilayer membranes, transferred to topographically structured polydimethylsiloxane (PDMS), are used as mechanical sensors. Due to the membranes' semipermeability, high-molecular-weight molecules can be either entrapped inside them or excluded, thus generating an osmotic pressure. This leads to a deformation. We investigate the deformation as a function of the osmotic pressure and present an analytical theory that fully describes the data. Thus, osmotic pressures can be determined quantitatively. The individual osmotic-sensitive elements have only microscopic dimensions, and arrays can be easily produced.     

Osmotic deswelling of weakly charged poly(acrylic acid) solutions and gels

The osmotic pressure of weakly charged aqueous poly(acrylic acid) (PAA) solutions and the swelling pressure PAA gels were studied by osmotic deswelling at different degrees of ionization (α). In solution, the osmotic pressure was found to scale linearly with concentration, whereas the scaling power of the swelling pressure of gels was higher (1.66). The effect of the ionization degree on the osmotic coefficient in PAA solutions was in agreement with the theory of Borue and Erukhimovich [Macromolecules, 21 , 3240 (1988)]. Ionization increases the swelling capacity of the PAA gels until a plateau is reached at about 35% neutralization. The concentration at equilibrium swelling scales as C_e ～ α^?0.6. The contribution of the network to the gel swelling pressure is evaluated by subtracting the osmotic pressure of the polymer solution at the same concentration and degree of ionization. In swollen gels the extended network opposes swelling. As the gel is osmotically deswelled, a state of zero network pressure exists at a certain concentration, below which the network elasticity favors swelling. The crossover concentration shifts to lower values as the degrees of ionization increases. © 1995 John Wiley & Sons, Inc.     

Calcium induced volume transition in polyelectrolyte gels

The osmotic properties and the small angle neutron scattering (SANS) behaviour of fully neutralized sodium polyacrylate gels are investigated in the presence of calcium ions. Analysis of the SANS response displays three characteristic length scales, two of which are of thermodynamic origin, while the third, associated with the frozen-in structural inhomogeneities, is static. The SANS results are consistent with direct osmotic observations which indicate that the thermodynamic properties cannot be adequately described by a single correlation length. The concentration dependence of the osmotic pressure displays a power law behaviour with an exponent that decreases with increasing calcium concentration.     

Modified Gas–Liquid Separator for the Determination of Mercury with Cold Vapor Flow Injection-Inductively Coupled Plasma Optical Emission Spectrometry

A phase separator for flow injection (FI) volatile compounds generation combined with inductively coupled plasma optical emission spectrometry (ICP-OES) was developed. The separator was constructed using a glass tube with a minimal dead volume respect to the classical U-tube separator. A peristaltic pump was used to aspirate the drained liquid and control the filling level, improving the reproducibility of the measurements and avoiding turbulence in the ICP. This device is simple and easy to fit to any FI system. The proposed separator was used for the determination of mercury.