一种小型电解水装置的设计

在对霍夫曼水电解器存在问题分析的基础上,梳理水电解器的设计思路,利用拆解、溯因-控制、类比联想等思维方法,设计优化一种小型电解水装置--“1分钟水电解器”。在此基础上,对其使用及多样化的功能进行说明。     

用土法制成“洋的霍夫曼电解器”

化学通报第5期(1960年)中学化学教学栏发表了曾宪春同志的“土的霍夫曼电解器制造法”,我认为有进一步改革的必要,根据曾同志的制作和一般水电解器沒有多大的区别,使用不方便,例如在两根滴定管中裝水就很不方便,另外,收集的氧气和氫气不能进行試驗(曾同志的說法是有錯誤的,因为收集的氫气和氧气如果不在水平面以下,那是检查不出来,活塞一开,由于滴定管中的水位高于水平面,就因重力而下降,放不出氫气和氧气。如果收集氫气和氧气在电解水的水平面以下,那么就一定要等很多的时間,所以我在教学中应用滴定管和一些玻璃管可以做出和洋的完全一样的霍夫曼电解器,如图1所示。在两根滴定管中間有一支玻璃管上端再套一段較大的試管,用以儲电解的水。     

投影实验之一——水的电解

常用的演示水电解的实验装置是霍夫曼电解器。这一演示装置只适用于30—40人的小教室,在大教室中不易看清。我们用有机玻璃制成的电解器,并用投影装置进行演示,在二百人的大教室中,不论是电解过程中产生的小气泡,和电解生成的氢气和氧气的体积比都看得十分清楚。一、水的电解器的制作图中所示的是电解器的前视图,主要由有机玻璃做成。     

电解水实验的再探讨

电解水实验是初中化学教学中的一个重要又难做的演示实验,到目前为止推荐的各种实验装置和方法不下二、三十种.课本里原来采用的是霍夫曼水电解器,这种仪器较贵,而且实验效果不理想.     

基于微型电解器的化学反应计量关系探究——新课程化学实验教学例谈

利用纽扣电池、微型漏斗和注射器组合成的简易微型电解器,可以对硫酸铜溶液的电解反应中的化学计量数进行定量探究。     

小型封闭式电解器的新设计

本文介绍一种小型封闭式电解器,它制作简单,使用方便。以电解饱和NaCl溶液为例,对电解器的制作和使用说明如下:1 电解器的制作 如图所示进行组装,要求是:     

电解预浓缩技术在原子吸收分光光度分析中的应用

本文介绍了电解预浓缩技术的基本装置和各种工作电极材料,重点评述钨丝工作电极在火焰和无火焰原子吸收分析中的应用及其利弊,指出采用电解后的钨丝直接作原子化器可以弥补仪器设备的不足。最后表列出该技术在原子吸收分析中的应用现状。     

介绍几件优秀简易自制教具

由国家教委教学仪器研究所与联合国科教文组织中国全国委员会秘书处联合举办了1988年全国简易自制教具评选活动。有33件化学自制教具参加了评比,共有5件获奖。其中,酒精灯强火器获一等奖：化学简易天平,气压式水电解器、电解质导电演示器获二等奖：固气反应装置获三等奖。     

“土”的霍夫曼电解器制造法

在讲初中化学第五章第一节“水的組成”时,没有霍夫曼电解器,因而不能进行实驗。但要制造和这相似的仪器却又需要一些很貴重的材料,如铂絲等。后来就利用手电筒电池的碳棒做电板试制成功,效果良好。仪器的安装方法是:用一个大烧杯,杆內装五分之四的清水,然后滴入3—4毫     

水的結构及其内部运动

前言在实际生活、生产和科学研究中,我們无时不在直接和間接地和水打着交道。許多化学反应是在水里进行的,許多物质的性貭是在水溶液里进行考察的。例如我們往往对于許多电解貭和非电解貭水溶液的兴趣超过了电解貭和非电解貭本身。实际上,一个水溶液的性貭是溶貭和水所共同体現的。水的作用决不可忽視,特别是一些稀的水溶液。因为水占着数量上的絕对的优势,因此我們需要对水进行认真細致的研究,这有助于我們更深入地了解溶液内部的情况,弄清許多反应的机理。物质的性貭决定于它的内部結构,物貭的一切外部表現都是其內部运动的綜合結果。因此关于水的結     

Investigation of the sorption of water vapor on cation-substituted vermiculite. 2. Thermodynamic description of sorption equilibria

The changes in the thermodynamic functions of the sorbents were calculated for the first time from measurements of the deformations of vermiculite during the sorption of water vapor and adsorption-calorimetric data.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Institute of Colloid Chemistry and the Chemistry of Water, Academy of Sciences of the Ukraine, 252180 Kiev. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1270–1275, June, 1992.     

Thermodynamics of ionization of water over wide ranges of temperature and pressure

We have summarized results of many experimental investigations of the thermodynamics of ionization of H₂O(liq.) from 0–300°C and from 1.0 atm to nearly 8000 atm. Results of these investigations (equilibrium constants, enthalpies of ionization, heat capacities, partial molal volumes, and compressibilities) have been used for a number of thermodynamic calculations. It is particularly noteworthy that it is possible to use thermal data from 0–145°C with an equilibrium constant for 25°C in calculating reasonably accurate equilibrium constants for temperatures as high as 300°C. Similarly, it is possible to use volumetric data that refer to 1.0 atm in calculating useful equilibrium constants that apply for pressures as high as 2000 atm.Much of the work reported here was done while the author was on leave at the University of Lethbridge.     

Thermodynamics of lonization of aqueous lodic acid,an “almost-strong” electrolyte

We have made calorimetric measurements of enthalpies of dilution of aqueous iodic acid and have used these results for evaluation of the standard enthalpy of ionization of HIO₃(aq.). We have also made calorimetric measurements of enthalpies of addition of perchloric acid solution to aqueous solutions of KIO₃, KNO₃, NaIO₃, and NaNO₃ and have used these results to obtain further values for the standard enthalpy of ionization of HIO₃(aq.). On the basis of all these results, we have selected H^o=–660±125 cal-mole^–1 as the best available standard enthalpy of ionization of HIO₃(aq.) at 298.15°K, compared to the previously accepted –2400 cal-mole^–1. Using the best available K=0.157 for ionization, we also obtain G^o=1097 cal-mole^–1 and S^o=–5.9 cal-^oK^–1-mole^–1 for ionization of HIO₃(aq) at 298.15°K.On study leave from Department of Inorganic and Analytical Chemistry, LaTrobe University, Bundoora, Victoria, 3083, Australia, to University of Lethbridge.On study leave from Department of Chemistry, University of Wollongong, Wollongong, N.S.W. 2500, Australia, to University of Lethbridge.     

Thermochemical study of aliphatic and phenyl-substituted geminal diacetates

The standard enthalpies of combustion _c H ^o of aliphatic diacetates1 and aromatic diacetates2 were measured calorimetrically. The enthalpies of vaporization _vap H ^o or sublimation _sub H ^o of1 and2 were obtained from the temperature function of the vapor pressure measured in a flow system. From _f H ^o(g) of1 and2 new values of group increments for the estimation of standard enthalpies of formation of these classes of compounds were derived. The geminal interaction energy between the geminal acyloxy groups shows no anomeric stabilization.Geminal Substituent Effects, Part 12, for part 11 see Ref. 7.     

Relation between characteristic adsorption energy and internal pressure in the theory of volume filling of micropores

An equation for the internal pressure acting on an adsorbate in micropores was obtained on the basis of the assumption that the chemical potential of an adsorbate in micropores is equal to that in an equilibrium gas phase and using the Dubinin-Radushkevich equation. The empirical relation between the characteristic adsorption energy and the half width of pores was expressed in terms of internal pressure and diameter of adsorbate molecules. The two-dimensional pressure was calculated for micropores with plane-parallel walls, where the width of a micropore coincides with the diameter of an adsorbate molecule. The results obtained were compared with the two-dimensional pressure of a monolayer on a free planar surface for an adsorbate and adsorbent of the same nature.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1928–1930, October, 1995.     

Thermochemistry of aqueous solutions of alkylated nucleic acid bases. VIII. Enthalpies of hydration of 6-alkyluracils

Enthalpies of solution in water H _sol ^o and enthalpies of sublimation H _sub ^o were determined for a number of crystalline derivatives of uracil: 1,6-dimethyluracil (m ₂ ^1,6 Ura), 1,3,6-trimethyluracil (m ₃ ^1,3,6 Ura), 6-ethyl-1,3-dimethyluracil (e⁶m ₂ ^1,3 Ura), 6-propyl-1,3-dimethyluracil (pr⁶m ₂ ^1,3 Ura) and 6-butyl-1,3-dimethyluracil (but⁶m ₂ ^1,3 Ura). Standard enthalpies of hydration H _hydr ^o and standard enthalpies of interaction H _int ^o of the solutes with their hydration shells were calculated. The data obtained show that dependence of H _int ^o on the number of-CH₂- groups of n-alkyl chain added upon substitution of diketopyrimidine ring is nonlinear. This finding is discussed in connection with results of X-ray diffraction structure determinations for the crystalline compounds.     

STUDIES ON THE REACTIVITY PATTERNS OF HETEROCYCLICS IN AQUEOUS DMSO‐INTERACTION BETWEEN POSITIVE END OF SULFOXIDE DIPOLE AND LONE PAIR ON RING NITROGEN IN PYRIDINE DERIVATIVES

Abstract

The signals for the α, β, and γ protons of pyridine exhibit a downfield shift in DMSO-d₆, compared to CCl₄ as solvent, the order being γ > β > α. This is attributed to an interaction between the positive end of the DMSO dipole and the lone pair of electrons on the ring nitrogen. This effect is also reflected in the faster rate of alkaline hydrolysis of ethyl isonicotinate over ethyl nicotinate and ethyl picolinate in aqueous DMSO relative to aqueous ethanol. Similar solvent effects are also observed in the pmr spectrum of pyrazine.     

Protonation of leucoemeraldine in the solid state and in solution

The protonation of leucoemeraldine in power form and in N-methylpyrrolidinone (NMP) solution by HCIO₄ and HBF₄ has been studied by x-ray photoelectron spectroscopy (XPS), infrared (IR), and ultraviolet (UV)-visible absorption spectroscopy. In powder form, less than 25% of the amine nitrogens can be protonated in the absence of oxygen. The effects of oxygen on the degree of protonation and the distribution of amine and imine units upon deprotonation of the salt are investigated. The degree of protonation in leuccemeraldine can be increased to about 50% with 3 M HCIO₄, similar to that achievable with emeraldine base in powder form. In NMP solution, leucoemeraldine is easily oxidized by dissolved oxygen. Protonation of both leucoemeraldine and emeraldine base in NMP solutions results in metastable species which gradually undergo deprotonation. The resulting products are affected by the O₂ content of the solutions. © 1993 John Wiley & Sons, Inc.     

钾明矾溶液水解度计算公式

根据盐类水解关系式和水的离子积计算公式,建立了计算盐类水解度和水解产物离解常数的完全方程式。计算值同实验值比较,钾明矾溶液水解度平均偏差为0.6％,离解常数pK_b=11.6±0.1,水的离子积pK_w平均偏差小于0.06,从而改进了苏联的计算公式。     

碳量子点上转换材料的制备及其应用研究进展

碳量子点(CQD)具有化学惰性,生物相容性和低毒性等优势,可能在能源、生物医药等领域得到广泛的应用. CQD可通过表面被聚合物(例如PEG)钝化而表现出很强的光致发光特性.在生物成像,疾病检测和药物输送中使用表面钝化后的功能化生物分子更为有效.并且碳材料由于其优异的电化学性能还展现出在催化、电子器件等许多领域广泛的应用前景.我们将对近年来碳量子点发光材料的研究进行总结,并讨论碳量子点在能源、环境和其他一些领域的应用.