第五章电化学Chapter5Electrochemistry
电化学原理-吴金平-2012第五章504-1-wu
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边界条件： x→∞
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边界条件：
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ci ( x, t ) 2 ci ( x, t ) Di 0 x , t 0 2 t x 初值条件：ci ( x, t 0) ci 0 边值条件1：ci ( x =, t ) ci 0 边值条件2：ci ( x =0, t ) ci
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x ci x, t c c c erf 2 Dt i c erf 2 Nhomakorabea
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电化学合成技术(Electrochemical synthesis)
电化学合成技术（Electrochemical synthesis）Refrigeration, cold, cold, extreme cold: reduce the temperature of local space to less than ambient temperature, known as refrigeration. Reduced to 123K is called pu cold, 123k-4.2 K is called deep cold, reduced to 4.2 K, which is called extreme cold.Dynamic pressure, the use of explosion (nuclear explosion, gunpowder, etc.), such as strong discharge produced by shock wave, in an instant effect on objects at high speed, can make the object interior pressure over dozens of GPa, even thousands of GPa, accompanied by a sudden warming. This high pressure is called dynamic high pressure.Static pressure: using the external mechanical loading way, by applying load slow gradually extrusion research object or sample, when its smaller, just inside the object or sample of internal high pressure. The high pressure produced is called static pressure because of the slow loading of the outside world (usually not accompanied by the temperature of the object).Primary pressure measurement: based on the known basic relationship between pressure and other parameters, the corresponding parameters are established to calculate the pressure. Secondary pressure test: the pressure is measured according to the variation of the pressure component.Vacuum, vacuum, vacuum pump: a given space that is lower than the atmospheric pressure. The degree of vacuum close to vacuum is in the system. A device for producing a vacuum is called a vacuum pump.Absolute vacuum gauge, relative vacuum gauge: measuring the vacuum measure, the direct measurement of pressure is called an absolute vacuum gauge; The measurement of the physical quantity relating to the pressure, its pressure scale needs to be calibrated with an absolute vacuum gauge, called a relative vacuum gauge.Illustrate manometry and secondary manometry answer: primary manometry: mercury manometer and free piston meter is according to the relation between p = F/a measurement function in the area of a force F, the two primary stress of pressure p.What are the criteria for dividing a vacuum? Answer: low vacuum, medium vacuum high vacuum, high vacuum, high vacuum, high vacuumThe operating characteristics of the vacuum pump are usually characterized by the following parameters:A limit pressure: the minimum pressure that can be reached at the entrance of the pump after a long period of pumping without gas escaping into the pump.B pumping rate: the volume of gas flowing through the air inlet section of the pump at a certain pressure.C maximum inlet pressure: the pressure of the pump before starting to work.D maximum pressure: the maximum pressure that the pump outlet can withstand without damaging the vacuum pump.E vacuum production rate: the quality of the gas discharged by the pump in a unit time.F compression ratio: the ratio of the outlet pressure of the vacuum pump to its inlet pressure.Chemical vapor deposition method: a technique of producing solid sediments in gas or gas-solid interfaces by gaseous or vapor pressure.Working principle of thermocouple, advantages and disadvantages. A: two different ingredients of conductor (called the thermocouple wire or hot electrode) synthesis loop at both ends, when the junction temperature is not at the same time, in the circuit will generate electromotive force, this kind of phenomenon called the thermoelectric effect, and the electromotive force called thermoelectric potential. Thermocouple is to use the principle of temperature measurement, which directly used for measuring the medium temperature is called the work at the end of the end (also known as measuring side), the other end is called the cold end (also known as compensation); The cold end is connected with the display instrument or supporting instrument, indicating the thermoelectric potential generated by the thermocouple. Advantages: high accuracy of measurement. Because the thermocouple is directly in contact with the measured object, it is not affected by the intermediate medium. The measurement range is wide. The commonly used thermocouple from - 50 ~ + 1600 ℃ are measured. The structure is simple and easy to use. Thermocouples are usually made of two different kinds of wires, and they are not limited by size and opening, and they are very convenient to use.The mechanism of high temperature fixation should be composed of two processes: chemical reaction in phase interface and material transfer in solid phase. The chemical reaction on thephase a, for different response systems, involves different stages,But all these include the following three processes: the contact between the reactants and the surface effect, the chemical reaction and the new phase composition, crystal growth and structural defect correction. When the reaction is active or liquid, the reaction will not be limited to the interface of the direct contact of the material, but may also be carried out along the free surface of the whole reactant particle. B. The reactant is diffused through the product layer. Migration diffusion can be carried out through crystal internal lattice, surface, interface or crystal fissure. Characteristics: 1) the solid opposite should generally include the reaction of matter in the phase interface and the process of material migration.2) it usually takes place at high temperature. 3) the entire solid should be controlled by the slowest speed. 4) the reaction products of solid reaction should be periodic: raw materials, original products, intermediate products, and final products.In chemical transport reaction, how to select and control temperature according to the heat effect of the reaction? A: if the reaction is endothermic reaction, ΔH is positive, then control source area temperature T1, T2 is higher than deposit zone temperature T2 is greater than the T1, namely this kind of reaction is to transport material has a high temperature to low temperature area. Conversely, when the reaction is exothermic reaction, Δ H negative, then control source area temperature is lower than the deposition area, namely the T2 is less than the T1, this kind of reaction is the material to the high transportation by the low temperature area.To prepare solid powders under high temperature and reducing atmosphere conditions, which equipment are needed and how to install them? Answer: equipment: tube furnace, electrolytic hydrogen plant. A thin layer of WO3 is sprinkled into the nickel boat, and the flow of the hydrogen is gradually moving the nickel boat through the tube, then through the high temperature zone into the cooler. This process is divided into two stages, the first stage is to make the WO3 at 720 c, reductive into brown WO2, then will get WO2, mixed with the same amount of WO3 and mixture in 800 ~ 860 c temperature reduction of metal tungsten, in the first stage of the reduction furnace temperature along the pipe heating parts from 520 c heats up to 720 c. In the second stage of the reduction, the furnace temperature increased from 650C to 860C. The quality of WO3 in each nickel boat was 50 ~ 180g because of the size of the furnace usedCommonly used refrigeration methods. Answer: the common method to cooling can be divided into physical methods and chemical methods, one of the commonly used gas adiabatic expansion refrigeration and cases of refrigeration, another half of the semiconductor refrigeration, gas throttling, eddy current cooling, adiabatic deflated refrigeration, thermoelectric refrigeration.The storage and transfer of liquefied gases: the containers of liquefied gases, which are different from the size and purpose of the volume, usually have low temperature containers, liquid gas storage tanks and so on. Small containers consist of a two-layer copper ball, which is divided into liquid nitrogen and gas containers. The liquid gas storage tank is composed ofthe outer shell, adiabatic structure and the mechanical structure of the inner and outer shell. There are many ways to go from a liquid gas plant to a liquid. Such as liquid air removed from a liquid air tank, the available methods of dumping or with a small siphon, is a large amount of liquid air, a small rubber ball pump up available liquid air play.Hard chemical: originally refers to the high temperature solid instead should method, and with the development of the synthesis technology, the concept of hard chemical tend to "chemistry" extreme conditions, such as ultra high temperature, super high, super vacuum, plasma, etcSoft chemistry: a chemical reaction that is achieved under mild conditionsGreen chemistry: green chemistry refers to the use of chemical products only in the manufacture and application of chemical products (preferably renewable) materials, eliminating waste and avoiding the use of toxic and dangerous reagents and solvents. Today's green chemistry is chemical technology that protects the environment.Sol-gel synthesis: an organic metal compound, metal inorganic compound or the mixture of two kinds of the hydrolytic condensation process, gradually gel post-processing accordingly, finally get the new technology of oxide and other compoundsHydrothermal synthesis: in a certain temperat ure (100 ~ 1000 ° C) and pressure (1 ~ 100 mpa) under the condition of using thechemical reaction of synthesis in solutionCoprecipitation synthesis technology of the requirements of a metal ion salt solution of dissolved in the water large b precipitant to metal ion precipitation precipitation c at the same time according to certain stoichiometric ratio sol agglutination of synthetic process of a source material molecules polymerization, condensation, clusters and colloidal particles grew up the formation of sol b with former body polymerization and polycondensation, gradually form a network structure of the gel, in the process, can form a variety of polymer gel structure c aging, polycondensation reaction in the process continues until the form has a solid 3 d mesh structure d gel dry, accompanied by evaporation of water and volatile matter e pyrolysis stage, in the process, the reticular formation of the gel completely collapsed, before bodies decompose organic matter, completely volatile, at the same time, the crystallinity of target productInorganic salt hydrolysis and polymerization of type a hydrolysis: metal ion hydrolysis polymerization b: hydroxyl polymerization, polymerization metal organic molecular oxygen hydrolysis and polymerization of type a polymerization: the aggregation of alkylation, polymerization, bridge oxygen hydroxyl polymerHigh temperature self-propagating synthesis: materials are prepared using the heat energy of raw materials themselvesThe characteristics of the high temperature self-propagating technology energy fully, products with high purity and highyield, product defects and non equilibrium phase in the more concentrated, so as to make the product more flexible, can make certain the stoichiometric ratio of products, intermediate products and the stationary phase interfaceThe characteristics of high temperature and high pressure water are characterized by the increase of vapor pressure and the ion deposition of water. Water density, viscosity, surface tension and dielectric constant decreaseThe properties of other substances in water under high temperature and pressure change a SiO2: it is not soluble in water at normal temperature, and the solubility can reach 0.16% with the increase of temperature. The solubility of SiO2 in NaOH solution can reach 2.4% b NaBr at room temperature, which is 100% dissociated in water, and the dissociation degree decreases at high temperature and high pressure, and the recrystallization occursThe reaction of qian yitai's preparation of diamond with solvent heat is as followsCCl + 4 na - > C + 4 nacl reaction conditions is 700 ° CHigh temperature and high pressure should also convert graphite into diamond. The design of the experimental design for the preparation of diamond was analyzed by using non-hydrolytic Na as solvent. The three-dimensional network structure of diamond is C (sp3 hybridization), two-dimensional plane structure of graphite is C (sp2 hybridization) C in the CCl is sp3 hybridization, so you don't have to graphite, diamond, C toreplace the Cl in CClElectrochemical synthesis: a method of synthesis by electrochemical reaction.Photochemical synthesis: photochemical reactions that are difficult or must be synthesized by chemical reactions with a chemical reaction.Decomposition voltage: the electrolyte begins to decompose the voltage.Overvoltage: the difference between the actual starting voltage and the theoretical decomposition voltage.Plasma: plasma is also called plasma, which is the ionized gas formed by the ionization of the atoms and atoms after the partial electrons are ionized. It is a state of highly ionized matter, a collection of positive and negative ions, electrons and neutral particles.Microwave synthesis technology, the use of microwave strong electric fields, generated in the microwave using thermodynamic method is less than the upper state atoms, molecules and ions, thus can make some on thermodynamics was not able to response to the synthesis technology.When metal deposition is carried out in electrochemical synthesis technology, how does the current density affect the morphology of the metal? Low - crystal growth time sufficient, not to form new nucleation, large, coarse. High - form morenuclei, tiny and even powdery grains. High - the crystals tend to grow in the metal ion concentration and grow into a tree.How does hot plasma come about? How is cold plasma produced? Hot plasma is produced by arc or ion moment. The cold plasma is produced by low intensity arc, microwave heating and glow discharge.The key to the growth of crystal growth in solution? A solution should be sufficiently high to eliminate the micro-crystal b to find the quasi-saturation point c to be strictly sealed in the growth process by the high precision cooling dThe lifting method of the growth crystals in the melt, the moving crucible method and the equipment of the zone melting method,Advantages and disadvantages of various methods? Pulling method advantages in the process of growth, a class to observe the growth condition of crystal directly, that provides a favorable conditions to control the crystal shape b crystal growth on the surface of the melt child accidentally place and do not contact with the crucible, can significantly reduce the stress of the crystal and prevent crucible wall send generating nuclear c can convenient use directional seed crystal and the "neck". Get a different orientation of single crystal, reduce the dislocation density in the crystal, reduce the Mosaic structure, improve the integrity of the crystal d to faster the rate of growth of high quality crystal defects of a general to make container with crucible, lead to melt with varying degrees of pollution when the melt containing volatile matter, bcontrol component is difficult to use c to have certain limitationsMoving crucible advantages due to seal the raw material in the crucible, a reduced can cause leakage and pollution of the hair, to the composition of crystal easy control operation, can grow a large size of crystal, crystal varieties can grow to be also many, and easy to realize programmed growth c because each crucible melt can separate nucleation, so that we can in a crystal furnace into several crucible, at the same time, it may improve the yield and efficiencyShortcoming is not suitable for growth in the make a volume increase of crystal b because the crystals in the whole growth process in direct contact with the crucible, tend to introduce large internal stress in the crystal and more impurity c is difficult to directly observed in the process of crystal growth, growth cycle is long d if using seed crystal growth in the descent method, how to make the seed crystal in high temperature is neither completely fused, and must make it with partial melting to full growth, it is hard to control technical problemsZone melting method (1) the horizontal zone melting method merit a reduced the crucible melt pollution, and reduce the heating rate b zone melting process can be repeated, so as to improve the purity of crystals or make doping uniformity(2) the advantages of floating zone method doesn't need a crucible, melt with itself only contact, pollution can be reduced to a minimum b growth process is easy to observe drawback strict in heating technology and mechanicaltransmission device flame fusion method merit a growth of single crystal don't need crucible, do the high temperature resistance of the crucible, the material is saved, and avoid the pollution problem of crucible b oxyhydrogen flame combustion, the temperature can reach 2800 degrees Celsius, gu grow high melting point of single crystal growth rate and rapid d c can grow larger crystal defects of a flame temperature gradient is bigger, in the growth of single crystal in poor quality b because the heat source is burning gas, temperature control of stable c grow single crystal of the dislocation density is higher, larger internal stress d for volatile or easy to be oxidized materials, should not use this method single crystal growthCrystallization: the process of crystallization of a liquid metal into a solid metal forming a crystal.Phase change: the mutation occurs in a particular condition (or critical value) in the process of change in the external conditions.Partial coagulation: a kind of operation that condenses a mixture of steam to a certain temperature and the higher components of some boiling point in the original steam.Uniform nucleation: in a cold liquid metal, the driving force is obtained by the energy change of the liquid metal itself, which is directly nucleated by the embryos.Nonuniform nucleation: the process of crystallization of the embryo in a cooled liquid metal in the presence of othersubstances on the surface.Supersaturation: the concentration of a substance at a certain temperature, the concentration of the solution at the time of crystallization, and the saturation concentration of the substance at the temperature, or saturation.。
摩尔电导率
(1) 电极反应：Ag+ + e- = Ag (电解AgNO3溶液时的阴极反应）
因为 z = 1，所以若通过电量 Q = 96500 C ，
Q 96500C 1mol -1 zF 1 96500C mol
1 mol n(Ag) n(Ag ) n(Ag) ν(Ag) n(Ag ) ν(Ag ) 1 mol ν(Ag) ν(Ag )
所以阴、阳离子运动速度的不同，决定了它们迁移的电 量不同，也决定了离子迁出相应电极区的物质的量的不同。
定义：某离子运载的电流与通过溶液的总电流之比为该离 子的迁移数。记号为 t 。 若溶液中只有一种阳离子及一种阴离子，I+ 、 I- 及 I 分 别表示阳离子、阴离子运载的电流及总电流，则有：
2009年4月2日
2009年4月2日
电阻与电阻率的关系是： R
l As
电导与电导率的关系是： G κ
As l
3.7.2
其中，As 为导体截面积，l 为导体长度。 显然，溶液的电导率 与电解质的浓度 c 有关。 对于强电解质，溶液较稀时， 电导率近似与浓度成正比；浓度很 大时，因离子间相互作用，电导率 增加缓慢，并经过一个极大值后下 降。
第五章 电化学
2009年4月2日
电化学科学的定义（The definition of electrochemistry）
电化学是研究电现象和化学现象之
间的关系及电能和化学能相互转化
规律的一门科学。
2009年4月2日
§ 5.1 电解质溶液的导电机理及法拉第定律
1. 电解质溶液的导电机理
电子导体(金属等)导电机理: 自由电子的定向运动，导体本身不发生任何化学变化。 离子导体(电解质溶液等)导电机理: 离子的定向运动，导电同时发生电极反应。
电化学方法与原理 英文
电化学方法与原理英文Electrochemical Methods and PrinciplesElectrochemistry is a fundamental branch of chemistry that deals with the relationship between electrical and chemical phenomena. It encompasses the study of various processes, such as the generation of electricity from chemical reactions, the use of electrical energy to drive chemical transformations, and the behavior of materials in electrochemical systems. Electrochemical methods have a wide range of applications, from energy production and storage to corrosion protection and analytical techniques.One of the core principles of electrochemistry is the understanding of oxidation and reduction reactions, also known as redox reactions. In these reactions, electrons are transferred between chemical species, resulting in changes in their oxidation states. The driving force behind these electron transfers is the difference in the ability of the participating species to attract and release electrons, known as their reduction potential. By harnessing and controlling these redox processes, electrochemists can design and optimize various electrochemical devices and processes.Electrochemical cells are the fundamental building blocks of electrochemical systems. These cells consist of two electrodes, an anode and a cathode, immersed in an electrolyte solution. The anode is where oxidation occurs, and the cathode is where reduction takes place. The electrolyte provides the necessary ionic conduction between the two electrodes, allowing the flow of ions and the completion of the overall electrochemical reaction.One of the most widely recognized applications of electrochemistry is energy conversion and storage. Electrochemical cells, such as batteries and fuel cells, convert the chemical energy stored in fuels or reactants directly into electrical energy. Batteries, for example, use the principle of redox reactions to generate a flow of electrons, which can then be used to power various electronic devices. Fuel cells, on the other hand, generate electricity by combining fuel (such as hydrogen) and an oxidant (such as oxygen) in an electrochemical reaction.In addition to energy applications, electrochemical methods are also used in a variety of analytical techniques. Electroanalytical methods, such as potentiometry, voltammetry, and electrochemical sensors, utilize the principles of electrochemistry to detect and quantify the presence of specific chemical species in a sample. These techniques are widely used in fields like environmental monitoring, healthcare, and chemical analysis.Corrosion is another area where electrochemistry plays a crucial role. Corrosion is an electrochemical process that involves the deterioration of materials, usually metals, due to their interaction with the surrounding environment. Understanding the electrochemical principles underlying corrosion enables the development of effective strategies for corrosion prevention and mitigation, such as the use of protective coatings, cathodic protection, and the selection of corrosion-resistant materials.Electrochemistry also finds applications in the synthesis and processing of materials. Electrochemical techniques, such as electroplating and electrodeposition, are used to deposit thin filmsor coatings of various materials onto a substrate. These processes are employed in the production of electronic components, decorative finishes, and protective coatings.The field of electrochemistry is constantly evolving, with new developments and applications emerging as our understanding of the underlying principles expands. Researchers continue to explore innovative electrochemical technologies, such as energy storage systems, fuel cells, and electrochemical sensors, to address pressing global challenges related to energy, the environment, and healthcare.In conclusion, electrochemical methods and principles arefundamental to a wide range of scientific and technological fields. From energy conversion and storage to analytical techniques and material processing, the principles of electrochemistry underpin numerous important processes that shape our modern society. As we continue to push the boundaries of scientific knowledge, the importance of electrochemistry will only grow, making it a crucial area of study for scientists and engineers alike.。
电化学2
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可逆电池电动势的取号
rGm=-zEF
自发电池：
非自发电池：
rGm<0，E>0 rGm>0，E<0
例如：
Zn(s)|Zn2+||Cu2+|Cu(s) Zn(s)+Cu2+→Zn2++Cu(s)
Cu(s)|Cu2+||Zn2+|Zn(s) Zn2++Cu(s)→Zn(s)+Cu2+
（3）电池中所进行的其它过程（如离子迁移等）也必 须可逆。（主要是要消除液接电势，盐桥能降低液接电 势，但不能完全消除液接电势，双联浓差电池则能完全 消除液接电势。）
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5.6 电动势产生的机理（了解）
电极－溶液界面电势差
液体接界电势和盐桥 接触电位（金属与金属间的接触）
rGm<0，E>0 rGm>0，E<0
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电动势产生的机理
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电动势产生的机理
2：液体接界电势和盐桥(见P168)
对盐桥作用的说明：
盐桥中离子的r+≈r-， t+≈t-，使Ej≈0。 常用饱和KCl盐桥，因为K+与Cl-的迁移 数相近，当有Ag+时用KNO3或NH4NO3。
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对消法测定电动势的原理图
调节电阻使检流计G指示为零 ，工作回路与被测回路之间
电化学
二、离子强度 I=1/2∑ mBZB2 lgγ± = - 常数× I ½ 此式仅适用于离子强度小于0.01mol Kg-1的稀溶液。
三、强电解质溶液的离子互吸能力 离子氛 德拜-休格尔极限公式
第五节 原电池
一、化学反应与原电池 二、可逆电池与不可逆电池 可逆电池特点：可逆条件下放电,所作的功最大. 可逆电池必须满足的条件：
离子的电迁移示意图
第二节 电解质溶液的电导
一、电导 定义：电阻的倒数 L=1/R1 单位：S（西门子）或 Ω-1 （欧姆 -1 ）
二、电导率 定义：电阻率的倒数
κ =1/ρ =（1/R）（l/A）=L（l/A） 单位：S m -1 物理意义：两平行电极面积各为1m2 ，两极间距离为
1m时电解质溶液的电导。
2 按实际顺序用化学式从左到右依次排列出各电池物 质及其存在状态(气、液、固)，气体要标明压力， 溶液要标明浓度或活度。
3 用单垂线“│”表示相界面，用逗号表示可混溶的 液相 之间的接界，用双垂线“‖”表示盐桥。
4 气体不能直接作电极，必须吸附在不活泼金属(如Pt， Au)上，电极附近的溶液被 电极上吸附的气体饱和。 写电池图式可略去不活泼金属。
γ+ =a+/m+ γ-＝ a-/m- γ=γ±ｖ= γ＋ｖ＋γ－ｖ－
a+=γ+m+ a-=γ-m-
a
=
a
ｖ ±
=
a
ｖ＋ ＋
a
ｖ－ －
(v=v++v-)
以CdCl2为例:
γ=γ=γCd2+γCl-2
a
=
a=
a
Cd2+
a
2 Cl-
(v=v++v-)
z-第五章电化学
Λ m Vm c
在相距为单位距离的两个平行电导电极之间，放 置含有1 mol电解质的溶液，这时溶液所具有的电导称 1 为摩尔电导率 Λ m ，单位为 S m2 mol。
电导和电导率的测定
Calculation of Molar Conductivity and Conductivity l 1 K cell 电导池常数 单位是 m 。 A 电导池常数可 用已知电导率的标 准溶液（常用KCl） 来测定。（可变电 容器以抵消电导池 中的电容）
当通电结束，阴、阳两极部溶液浓度相同，但比 原溶液各少离子的三倍， 3r，则正 离子导3mol电量，负离子导1mol电量。在假想的AA、 BB平面上有3mol正离子和1mol负离子逆向通过。
通电结束，阳极部正、负离子各少了3mol，阴极 部只各少了1mol，而中部溶液浓度仍保持不变。
第 五 章
Electrochemistry
发展历史
• 1600年Sir William Gilbert,观察到用毛 皮擦过的琥珀有吸引其它轻微物体的能 力，他把这种现象形容为“electric” • 1786年意大利解剖学家Luigi Galvani， 在解剖青蛙时发现，当手术刀触及到蛙 腿外露的神经时，蛙腿会剧烈地抽搐。 把蛙腿放在铁板上，用铁丝把蛙腿和铁 板相连时蛙腿也会抽搐。改用玻璃板和 玻璃棒后没用这种现象。认为这是生物 电现象。1791年发表了“关于电对肌肉 运动的作用 ”。
根据法拉第定律，当1mol电子的电量通 过电极时,电极上得失电子的物质的量也为 1mol（基本单元）。
法拉第常数
法拉第常数在数值上等于1 mol元电荷的电量。 已知元电荷电量为
1.6022 1019 C
F=L· e =6.022×1023 mol-1×1.6022×10-19 C
电化学 Microsoft Word 文档
第一章电化学理论基础1.1 电化学体系的基本单元1.1.1所有电化学体系至少含有浸在电解质溶液中或紧密附于电解质上的两个电极, 而且在许多情况下有必要采用隔膜将两电极分隔开。
1.1.2电极电极（electrode）是与电解质溶液或电解质接触的电子导体或半导体, 为多相体系。
电化学体系借助于电极实现电能的输入或输出, 电极是实施电极反应的场所。
一般电化学体系为三电极体系, 相应的三个电极为工作电极、参比电极和辅助电极。
化学电源一般分为正、负极；而对于电解池, 电极则分为阴、阳极。
现介绍如下。
工作电极（working electrode, 简称WE）: 又称研究电极, 是指所研究的反应在该电极上发生。
一般来讲, 对于工作电极的基础要求是: 所研究的电化学反应不会因电极自身所发生的反应而受到影响, 并且能够在较大的电位区域中进行测试；电极必须不与溶剂或电解液组分发生反应；电极面积不宜太大, 电极表面最好应均一、平滑的, 且能够通过简单的方法进行表面净化等等。
工作电极可以是固体, 也可以是液体, 各式各样的能导电的固体材料均能作电极。
通常根据研究的性质来预先确定电极材料, 但最普通的“惰性”固体电极材料是玻璃、铂、金、银、铅和导电玻璃等。
采用固体电极时, 为了保证实验的重现性, 必须注意建立合适的电极预处理步骤, 以保证氧化还原、表面形貌和不存在吸附杂质的可重现状态。
在液体电极中, 汞和汞齐是最常用的工作电极, 它们都是液体, 都有可重现的均相表面, 制备和保持清洁都较容易, 同时电极上高的氢析出超电势提高了在负电位下的工作窗口, 已被广泛用于电化学分析中。
辅助电极（counter electrode,简称CE）：又称对电极, 该电极和工作电极组成回路, 使工作电极上电流畅通, 以保证所研究的反应在工作电极上发生, 但必须无任何方式限制电池观测的响应。
由于工作电极发生氧化或还原反应时, 辅助电极上可以安排为气体的析出反应或工作电极反应的逆反应, 以使电解液组分不变, 即辅助电极的性能一般不显著影响研究电极上的反应。
第五章 电化学-1-pdf
难溶盐饱和溶液的浓度极稀，可认为 Λm Λ m 的值可从离子无限稀释摩尔电导率表值得到。 Λm
第五章
电化学
Λm Λ Λ m,+ m,
难溶盐本身的电导率很低，这时水的电导率就不能忽略:
(难溶盐) (溶液) (H O)
2
(难溶盐) Λm (难溶盐)
如果在电解池的阴极上发生如下的反应：
第五章
电化学
M z e M(s)
当反应进度为1 mol 时，需通入的电量为：
z
Q zF z+ F 1 mol z 96 500 C
输入任意电量Q时，在阴极上沉积出金属B的物质的量 和质量分别为
Q nB z+ F
Q m(B) MB z+ F
l R A
－电阻率
用电阻的倒数表示导体的导电能力：
1 1 A A G R l l
1
电导G的单位： -1 或 S（西门子）
－电导率，是电阻率的倒数，单位：Sm-1
导体的截面积为1m2，长度为1m时的电导；
相当于单位长度、单位截面积电解质溶液的电导。
长度 l
第五章
电解
电池
金属的防腐，材料保护，光电化学 生物电化学，电化学分析
第五章
§5-1 §5-2 §5-3 §5-4 §5-5 §5-6 §5-7 §5-8 §5-9
电化学
电化学基本概念 电导、电导率和摩尔电导率 强电解质溶液的活度和活度因子 可逆电池与可逆电极 可逆电池热力学 电极电势与电池电动势 电极极化现象 电解时的电极反应 金属的电化学腐蚀与防护
单位为 单位为
m3 mol1 mol m3
电化学课件5
jd = 0.62nFDi 3ν 6ω 2 ci0
2 1
ω = 2πn0 = u 0 y
上式表明：园盘电极表面扩散层厚度δ相等，i 也相等
电迁移传质对扩散电流的影响
溶液中无 supporting electrolyte，阳离子在阴极还原 a.溶液中反应物粒子的扩散流量 b.电迁移流量 达稳定后：(每一点离子浓度浓度稳定）
dci dE + v x ci − Di J i = ±ci ui dl dx
电极表面：加入大量supporting electrolyte 电迁移可忽略，扩散起作用。 bulk：液流速度D，U比对流小得多， 扩散,迁移可忽略 电极表面的简化！
电极/溶液界面附近反应物传质过程和数学简化
特点：
A
－
e +
J i,c = υ ci
J i = m U i ci∇φ − Di∇ci + υ ci
液相中的传质方式
dCi J 扩i＝-Di dx
1. 扩散 diffusion
Fick第一定律数学表达式
dc dx concentration gradient
“-”扩散方向与浓度增大方向相反
J 扩i ⎡⎛ ∂ci ⎞ ⎛ ∂ci ⎞ ⎛ ∂ci ⎞ ⎤ = − Di ⎢⎜ ⎟ +⎜ ⎟ +⎜ ⎟ ⎥ ∂x ⎠i ⎝ ∂y ⎠i ⎝ ∂z ⎠ k ⎦ ⎣⎝
Nernst-Plank 方程
• 进一步加入支持电解质，反应物电迁移的贡献可以忽略
dci J i = − Di dx
传质过程仅含扩散过程
§3-2
稳态扩散过程
ci = f ( x, t ) 非稳态，暂态 ci = f ( x) 稳态，扩散
《物理化学》第五章(电化学)知识点汇总
弱电解质： 电导率随浓度的变化不显著。
c/mol· dm-3
2. 摩尔电导率与浓度的关系 强电解质： 遵从科尔劳许经验关系：
m m (1 c )
m2· mol-1 Λ m/S·
HCl
NaOH AgNO3
Λ m －为极限摩尔电导率 弱电解质：
HAc
c /( mol dm )
3
$ RT aH 2 H / H ln 2 2 2 F aH
Cu
H
2
/ Cu
$ Cu 2 / Cu
aCu RT ln 2F aCu2
/ H2
$ H / H2
RT aH 2 ln 2 2 F aH
氧化态 ze 还原态
m Vm
m
1 Vm c
1mol 电解质
c
电导率
三、电导率、摩尔电导率与浓度的关系
1. 电导率与浓度的关系 强电解质： 浓度增加，电导率增加； 浓度增加到一定值后，低。 m-1 κ/S·
H2SO4
KOH NaOH NaCl HAc
2. 离子迁移数
定义：当电流通过电解质溶液时，某种离子迁移 的电量与通过溶液的总电量的比称为该离子的迁 移数。
Q r Q t ＝ Q r r－ Q Q－
Q t Q
Q－ Q Q－ －
r r r－
2. 摩尔电导率
是把含有1mol电解质的溶液置于相距1m的两个平行 电极之间，溶液所具有的电导。
( HCl ) ( NaAc ) m m m ( NaCl )
§5.4 溶液中电解质的活度和活度系数
电化学读书笔记全解
电化学（electrochemistry）作为化学的分支之一，是研究两类导体（电子导体，如金属或半导体，以及离子导体，如电解质溶液）形成的接界面上所发生的带电及电子转移变化的科学。
传统观念认为电化学主要研究电能和化学能之间的相互转换，如电解和原电池。
但电化学并不局限于电能出现的化学反应，也包含其它物理化学过程，如金属的电化学腐蚀，以及电解质溶液中的金属置换反应。
16-17世纪：早期相关研究16世纪标志着对于电认知的开始。
在16世纪50年代，英国科学家威廉·吉尔伯特花了17年时间进行磁学方面的试验，也或多或少地进行了一些电学方面的研究。
吉尔伯特由于在磁学方面的开创性研究而被称为“磁学之父”，他的磁学研究为电磁学的产生和发展创造了条件。
1663年，德国物理学家奥托·冯·格里克发明了第一台静电起电机。
这台机器由球形玻璃罩中的巨大硫磺球和转动硫磺球用的曲轴组成的。
当摇动曲轴来转动球体的时候，衬垫与硫磺球发生摩擦产生静电。
这个球体可以拆卸并可以用作电学试验的来源。
18世纪：电化学的诞生在18世纪中叶，法国化学家夏尔·杜菲发现了两种不同的静电，他将两者分别命名为“玻璃电”和“松香电”，同种相互排斥而不同种相互吸引。
杜菲因此认为电由两种不同液体组成：正电“vitreous”（“玻璃”），以及负电“resinous”（“树脂”），这便是电的双液体理论，这个理论在18世纪晚期被本杰明·富兰克林的单液体理论所否定。
1781年，法国物理学家夏尔·奥古斯丁·库仑在试图研究由英国科学家约瑟夫·普利斯特里提出的电荷相斥法则的过程中发展了静电相吸的法则。
1771年，意大利生理学家、解剖学家路易吉·伽伐尼发现蛙腿肌肉接触金属刀片时候会发生痉挛。
他于1791年发表了题为“电流在肌肉运动中所起的作用”的论文，提出在生物形态下存在的“神经电流物质”，在化学反应与电流之间架起了一座桥梁。
电化学的英语
电化学的英语《Electrochemistry: Understanding the Power of Chemical Reactions》Electrochemistry is a fascinating field of study that concerns the interplay between electrical and chemical phenomena. It deals with the relationships between electricity and chemical reactions, and has a wide range of applications in areas such as energy storage, corrosion prevention, and even medicine.At its core, electrochemistry is based on the concept of redox reactions, or oxidation-reduction reactions. These reactions involve the transfer of electrons between different chemical species, and are at the heart of many important processes in nature and in technology.One of the most widely recognized applications of electrochemistry is in the field of batteries and fuel cells. These devices rely on redox reactions to store and release energy, and are essential for a wide range of everyday technologies, from smartphones and laptops to electric vehicles and renewable energy systems.In addition to energy storage, electrochemistry also plays a crucial role in corrosion prevention and protection. By harnessing the power of redox reactions, scientists and engineers are able to develop coatings and treatments that can protect metal surfaces from corroding, extending the lifespan of infrastructure and machinery.In the realm of medicine, electrochemistry has found applications in fields such as biosensors and drug delivery systems. By leveraging the ability to control and manipulate redox reactions, researchers are able to develop novel technologies for diagnosing diseases and delivering therapeutic agents with unprecedented precision and efficiency.Overall, electrochemistry is a field with a wide range of practical applications and a deep understanding of the fundamental principles at the heart of many important processes. As our world continues to seek sustainable and efficient solutions to global challenges, the study of electrochemistry will undoubtedly play a key role in shaping the future of technology and science.。
物理化学课件：电化学
Kolbe）用电解法制备了有机酸。
1874年：英国物理学家能斯特（Nernst）提出了热力学公式，为电化学研究提供了理论基础。
19世纪末至20世纪初：电化学工业开始发展，包括电池、电镀、电冶金等领域。
电化学发展历程
电化学基本概念
由两个或多个电极组成，通过电解质溶液将化学能转化为电能的装置。
定义
电解过程可以用电解方程式表示，包括阳极反应和阴极反应，以及它们之间的关联。
电解方程式
电流效率是评价电解过程效率的重要参数，表示实际参与电化学反应的电量与理论电量之比。电流来自率定义电极材料
产物与电流密度关系
电合成过程
03
材料制备
通过电解和电合成方法制备新型材料，如电池电极材料、光电器件等。
电解和电合成应用
xx年xx月xx日
物理化学课件：电化学
contents
目录
电化学基础知识电池及电极过程电解和电合成电化学分析方法电化学研究前沿电化学应用领域
电化学基础知识
01
1780年：意大利物理学家伏特（Volta）用不同金属做电极，首次获得电能。
1800年：英国化学家戴维（Davy）发现电解现象，并开始用电解法制备金属。
在给定的电位范围内，用脉冲电压对电解池进行电镀或电化学沉积，同时测量电流响应，从而得到电流与电位的关系曲线。
脉冲伏安法
应用
用于研究电极反应动力学、表面吸附、双电层结构等，也可用于定量分析和鉴别化学物质。
优缺点
具有较高的灵敏度和选择性，但测试速度较慢，且容易受到电解池内阻和杂散电流的影响。
原理
01
在给定的电位范围内，以不同的扫描速率连续地改变电位值，并测量电流响应，从而得到电流与电位关系曲线。
第五章电化学Electrochemistry电子教案
二、法拉第定律 法拉第在归纳了大量电解反应的实验结果后， 于1833年提出了关于电解产物的量与通入的电量之 间关系的规律，即法拉第定律。
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法拉第定律 （1）电流通过电解质溶液时在电极上发生的化学反 应的物质的量正比于所通过的电量； （2）在不同电解质溶液中通入1mol电子的电量，则 在每个电极上发生电极反应的物质的量也为1mol。
l
R =ρ
A
l
式中 A
称为电导池常数，比例系数ρ称为电阻率
或者比电阻。
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电阻率的倒数称为电导率或者比电导，用符号κ 表示，单位是S•m－1。
11l
l
κ=
=
R
•
A = L•
A
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（三）摩尔电导率 摩尔电导率是指相距为1m的两个平行电极之 间放置含有1mol电解质的溶液时所具有的电导， 用符号Λm表示。
之相关的离子平均质量摩尔浓度m±如下：
1
a± =
(a
a
)
1
γ± =
(
)
1
m±
=
(m
m
)
很显然：
a± = 㱕m±/m°
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该电解质溶液的总活度a为：
a=
a
a
= a±ν
=（㱕m±/m°）ν
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二、离子强度 采用各种不同的实验方法测定强电解质的离子 平均活度系数γ±后，大量实验结果表明，在稀溶 液的范围内，影响强电解质离子平均活度系数γ± 的主要因素是溶液的浓度和离子的价数，而且离 子价数的影响比浓度的影响更为显著。
2020/5/20
05章_电化学
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二、电导、电导率、摩尔电导率
电导、电导率、摩尔电导率 电导的测定 电导率、摩尔电导率与浓度的关系 离子独立移动定律 几个有用的关系式 电导测定的一些应用
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电导、电导率、摩尔电导率
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2020/2/7
电解池(electrolytic cell)
电极①：
与外电源负极相接，是负极。
①
② 发生还原反应，是阴极。
Cu2++2e-→Cu(S)
电极②：
与外电源正极相接，是正极。 发生氧化反应，是阳极。 Cu(S)→ Cu2++2e-
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2020/2/7
F=L·e =6.022×1023 mol-1×1.6022×10-19 C
=96484.6 C·mol-1 ≈96500 C·mol-1
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2020/2/7
法拉第定律的数学表达式
Mz ze M Az- ze A
取电子的得失数为 z，通入的电量为 Q，则电极
电导池常数
Kcell
l A
单位是 m1 。
R
l A
Kcell
K cell
1
R
kR
因为两电极间距离 l和镀有铂黑的电极面积 A 无 法用实验测量，通常用已知电导率的KCl溶液注入电
正极、负极
电势高的极称为正极，电流从正极
正极：
流向负极。在原电池中正极是阴极； 在电解池中正极是阳极。
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原电池
电解池
正极┉┉┉阴极
正极┉┉┉阳极
负极┉┉┉阳极
负极┉┉┉阴极
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2021/1/16
电解池示意图 （电解HCl水溶液）
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原电池示意图
电解质溶液的导电机理为： （1）电流在溶液中的传导由正负离子的定向迁移 而共同承担； （2）由于两个电极上所发生的氧化还原反应，导 致电子得失，从而使电极与溶液界面处的电流得以 连续。
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四、电导滴定
第四节 溶液中电解质的活度和活度系数
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一、溶液中电解质的平均活度和平均活度系数
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设任意一强电解质 M A 在水溶液中全部电离： M A →ν+M z+ +ν－A z－
电解质的化学势可用各个离子的化学势之和来表示：
μB =ν+μ++ν－μ－
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三、德拜-休格尔极限定律
第五章 电化学 Chapter 5 Electrochemistry
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导体 凡是能够导电的物体称为导体，如金属和电解质溶 液。
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电化学装置分为两大类 将化学能转变为电能的装置称为原电池 将电能转变为化学能的装置称为电解池
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在原电池和电解池中，正负极以及阴阳极之间的 关系如下：
摩尔电导率。
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第三节 电解质溶液的电导测定应用
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一、水的纯度检测 二、弱电解质的电离度和电离常数的测定
α= m
m
由电离度可进一步计算出弱电解质的电离平衡常数K。
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Байду номын сангаас
三、难溶盐的溶解度测定
κ盐 = κ溶液 –κ水
c饱和 =（κ溶液 –κ水）/ m
之相关的离子平均质量摩尔浓度m±如下：
1
a± =
(a
a
)
1
γ± =
(
)
1
m±
=
(m
m
)
很显然：
a± = 㱕m±/m°
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该电解质溶液的总活度a为：
a=
a
a
= a±ν
=（㱕m±/m°）ν
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二、离子强度 采用各种不同的实验方法测定强电解质的离子 平均活度系数γ±后，大量实验结果表明，在稀溶 液的范围内，影响强电解质离子平均活度系数γ± 的主要因素是溶液的浓度和离子的价数，而且离 子价数的影响比浓度的影响更为显著。
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法拉第常数 1mol电子的电量称为法拉第常数，用符号 F 表示。 1F = 1e×L = 1.60217733×10–19×6.0221367×1023
= 96486C•mol–1≈96500C•mol–1 式中C是电量“库仑”的符号 。
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根据法拉第定律，要从含有MZ+离子的溶液中 沉积出n mol的金属M时，需要通过的电量为：
尔电导率Λm会增大，但强、弱电解质溶液的变化规 律并不完全相同。
2021/1/16
科尔劳许（Kohlrausch）根据大量的实验结果 归纳出在极稀的电解质溶液中，强电解质溶液的摩尔 电导率与其浓度c的关系为：
Λm = m(1 c)
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弱电解质溶液的摩尔电导率Λm与溶液的浓度c 之间不符合某种线性关系，不能用外推法求得弱电 解质的无限稀释摩尔电导率。这是因为，当溶液稀 释时，弱电解质的电离度迅速增大，溶液中的离子 数目急剧增加，使得其摩尔电导率迅速增大，而且 其浓度越低，摩尔电导率上升越明显。
l
R =ρ
A
l
式中 A
称为电导池常数，比例系数ρ称为电阻率
或者比电阻。
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电阻率的倒数称为电导率或者比电导，用符号κ 表示，单位是S•m－1。
11l
l
κ=
=
R
•
A = L•
A
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（三）摩尔电导率 摩尔电导率是指相距为1m的两个平行电极之 间放置含有1mol电解质的溶液时所具有的电导， 用符号Λm表示。
=ν+（μ+°+ RTlna+）+ν－（μ－°+ RTlna－）
=（ν+μ+°+ν－μ－°）+
RT lna( a )
= μB °+ RTlna
所以：
μB °=ν+μ+°+ν－μ－°
a=
a a
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定义对其于离强子电平解均质活度Ma±、A离子来平说均，活令度ν=系ν+数+γν±－以，及分别与
2021/1/16
二、法拉第定律 法拉第在归纳了大量电解反应的实验结果后， 于1833年提出了关于电解产物的量与通入的电量之 间关系的规律，即法拉第定律。
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法拉第定律 （1）电流通过电解质溶液时在电极上发生的化学反 应的物质的量正比于所通过的电量； （2）在不同电解质溶液中通入1mol电子的电量，则 在每个电极上发生电极反应的物质的量也为1mol。
Q = （n×Z）F
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三、离子的电迁移和迁移数
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第二节 电解质溶液的电导
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一、电解质溶液的电导 （一）电导
电解质溶液的导电能力可以用电阻的倒数来 表示，称为溶液的电导，用符号 L 表示：
1
L=
R
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（二）电导率
实验表明，溶液的电阻R与两个电极之间的距 离 l 成正比，而与浸入到溶液中的电极面积 A 成反 比， 即：
c Λm = κVm =
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二、电解质溶液的电导测定
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三、电解质溶液的电导与浓度的关系 1. 电解质溶液的电导率κ与溶液浓度c的关系
（1）强电解质溶液 （2）弱电解质溶液
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2. 电解质溶液的摩尔电导率Λm与溶液浓度的关系 一般来说，当电解质溶液的浓度减小时，其摩
2021/1/16
溶液的离子强度I被定义为：
I = 1
2
B
m
B
Z
2 B
式中mB为某种离子B的质量摩尔浓度，ZB为离子B所 带的电荷数，即离子B的价数。
2021/1/16
溶液的离子平均活度系数γ±与离子强度I之间的 关系为：
lgγ±= –常数 I
式中常数＞0，具体数值与温度以及溶剂的种类有 关。
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四、离子独立运动定律
在无限稀释的溶液中，所有电解质（无论强弱）
都全部电离，离子间彼此独立运动，每一种离子对
电解质溶液的导电都有恒定的贡献。这就是科尔劳
许在研究了大量电解质的有关实验数据后提出的离
子独立运动定律，用公式表示为：
m
=
m
,
+
m
,
式中
m
,
和
m
,
分别为无限稀释时正、负离子的