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本帖最后由 liuling080629 于 2012-12-11 00:03 编辑
看到论坛里的，真的化学类的资料才珍稀动物，所以也想着，自己也过来，也就是记下流水账说下复习还有当天的行程，再附上自己的部分复习资料吧，可能很简单，但是都是自己语言准备，所以大家看看就好，参考下，评论啥的留点情哈。还有啊，欢迎大家加入我们的化学群哇，很有爱的说，27124401哦，，，
一、准备过程
我是9月17到寄的材料，因为那时候，群里大家都说，要赶紧寄，否则等到紧张期的时候，不好过，那时候就各种火急火燎的把材料给寄了，公证用的是英语，然后花了将近2000大洋吧，公证了8分。包括，大学成绩，高中毕业证，花名册，在读证明。本人的小学毕业证和初中毕业证都是用的是证明代替，注意，证明要是原件，我的当时，落款也只有学校名称和盖章而已，并没有网站上说的那么严苛。对了，公证花了三天，还是蛮快的，对了，还有照片，我用的是白底，虽然有的人说什么样的都可以。还有，善意建议下，如果决定英审，但是又是学了点德语的，不要费心思去交什么学时证明，真心没必要的，不会加分的。你可以再面审的时候直接说，我可以德语介绍，这样的印象分可能还来的高些。
二、审核
后来浑浑噩噩两个月就过去了，我是被通知在11月5号审核，被自己推迟了下，电话差不多是提前了两周打给我的把，接电话的时候全身那个抖哇，不解释，，挂完电话就兴奋了一晚上。第二天就开始制定计划了。因为之前没有做什么准备，帖子啊，经验什么的，我看的也不多，所以就蛮上了。自己给自己的计划就是看课表，然后写中文框架，再写英文，然后再背。推荐下：如果时间够充裕的话，强推直接看英语原文书，我就是在图书馆上直接借了一本general chemistry英文版，然后自己慢慢看的，收获很大。好吧，重新理下，我的复习步骤。
1、拿到中文课表。分类。确定重点复习课程。重点复习课程的相关连接，还有重点复习课程的几个知识点，把想要看的知识点压缩在一张图上。其实也就是四大化学，波谱，化工原理，化学工程，这几门课（ps大一大二的课程我基本没有看）还有要注意自己的高分课程和优秀课程，被问的可能性很高。
2、看着框架，开始按着课本目录写中文概述。一开始，会觉得每个都是重点，没事，你就列，反正后来都会压缩，这是一个渐渐上手的过程。这样之前的简单框架就丰富了很多知识点的。（ps纸张要大，我是浪费了超级多的A4的，呵呵）
3、压缩中文概述，确定要讲解的知识点，我是尽量挑简单的说哈，这样比较轻松，也比较有把握。所以，满满的框架会变成比较精炼的了。确定了以后，就开始要自己翻译了，因为看原文书，所以翻译这快真的会轻松很多。对了，还有狠狠感谢下维基百科，真的帮忙很多。这样，翻译什么的，就比较容易搞定了。做完这些差不多过了10天。然后就只剩下五天的时间背和准备常规问题以及自我介绍。
4、背了三天，开始准备常规问题，我是把每个问题都下载到电脑里，然后再用自己的语言把每个问题都回答了一边，打印下来一起背。建议，常规问题，自己好好准备下，这是必问的，然后大家不尽相同，所以自己整理会有把握的多。
三、审核前夕及进行时
11月3号的火车晚上Z65，南昌到北京，在火车上就没有再看资料了，条件也不允许，对了，这里推荐大家一号办法，把自己所有的资料全部录到手机，分段录的那种，一门一门课的，自我介绍的，常规问题的，到了火车上，使劲放就可以了。11月4号到了北京，还下雨夹雪，在这里，真心要感谢来火车站接我这路痴兼白目的小陈同学，god bless you ！真心感激哇，，，，忘了说，我定的酒店是7天连锁的燕莎中心店，因为有活动，新会员首夜入住77元，所以很划算的说，离的也很近的，环境也还好吧。四号到了北京，好好睡了一觉，有钱的娃呢，可以去尝试下全聚德，一出门就有，我是到了味多美的面包单凑合了下的，不过也挺好吃的。顺带的话去看了留德审核部，也就是传说中的亮马河大厦，接下来基本没怎么看资料了，都是在放录音，也会在看电视，休息下的，比较放松，因为也看不了什么了。到了第二天，也就是周一上午，睡到自然醒，中午的时候没有吃午饭，紧张，没心情了，然后到了星巴克，在那遇到了同道中人也就是成都的小P同学啦。一起喝咖啡，看资料啥的，时间还过的很快的说，到了12点45分的时候，就直接到了审核部门口等，那个时候门口已经有人了，包 我俩就刚好8个人。大家都比较忐忑吧，然后有一淡定兄，戏称吧，反正说个没完，当时是被吓的够呛的说，真好奇淡定兄过了没，呵呵。然后就是常规的进房间，核对名字，填信封，照相，挺安静的当时，没有怎么说话，
四、审核进行时
我是第三个被叫进去的，是一个白头发的老爷爷，挺和善的额，首先就是要把照片给他，然后把所有的东西存放起来，特别是手机，他也会强调的。然后到一超小的隔间做笔试题。题目英文德文都在一张纸上，没有选择，他是直接给我的，但是他还是会问用哪种语言审核的，直接说就好了。笔试时间的长短，取决于你之前的那个人的面试时间。我是比较充裕的，笔试题目比较简单，就一道题，但是三小问，只要不出问题，都是可以回答出来的。我的是涉及到无机非金属的重要反应，不能漏题，呵呵。答完后，我还再重新抄了一遍，呵呵，大概20分吧，就可以去面试了把答题给审核官。之后就是常规的自我介绍，真的超级简短的，知道你是谁就好了，我当时紧张说的超级颠三倒四的。然后是常规问题，为什么你说英语却选择到德国留学，你在德国的plan是什么，想读哪个学校，毕业后怎么打算。结婚没？就这些，好好准备不会刁难你的。然后进入到专业介绍，先是直接提问，他会给你一张纸，写些东西，问你，然后要你回答他想知道的内容，一般就是些基本的物质区分，然后他会在你递交的语言成绩单上标注想询问的课程，我当时标注的大概有5.6门的样子，然后他随机的点着六门之二。我的是波谱分析和有机化学实验。其实知识点自己都有准备，但是这老师的问法太奇葩，当时就把我弄晕掉了。比如，他问我，苯里面的角度是多环己烷的内角度是多少？怎么区分？说波谱分析的时候，说了下紫外分光光度计，问我什么时候复合光，什么是单色光，或者指着一东西说，what is this？说道实验的时候，更奇葩就来了，我说的是cannizzaro反应，然后一氧化产物，一还原产物，还没说完，他直接来句，why this is oxidation product？当时我就蒙了，什么叫why啊，那我就说，要不我和你说机理吧，然后人家直接来句，no mechnism，can you understand me ?我就泪奔了，，，无语哇，我就只能各种画图了，反正最后我是没整清楚哈，老爷爷也就只好问下个问题，叫我画下装置啊，说下步骤啊，什么的。最后就是到了笔试题目，他会先说，你答的正确与否，答对了，然后，他就问，why？当时支支吾吾没有回答，然后他直接扔个炸弹过来说，you understand this ,or you just know this from the book?我就只能瞎掰了，然后人家直接说，时间到了，然后我的审核就完了，
五、审核结束
从大厦出来的时候，想死的心都有，回答的真的超级不顺利的，然后就到了7天打包行李，直接打的到了富山青旅，打算在北京玩几天。打算自取么。玩了大概四天吧，周四知道自己过了，兴奋不已，周五去领的证书，那时候快下班了，等拿到证书想回去的时候，戏剧性的一幕来了，我证书的大学名称给搞错了，而且当时人家已经下班了，赶回去也不行，而且大家也知道周五的审核部是不上班的，但是我还是决定去尝试下，为了攒人品，还是在星巴克拿了杯摩卡，转换心情，然后就上楼蹲点去了，真的是蹲点哇，心情超级忐忑的，反正各种波折，最后还是有人处理了，到了今天我才拿到证书，其中纠结，就不说了哈，现在附上我自己整理的复习资料。
Cannizzaro反应
The aldehyde without a-active hydrogen atom ,under the action of strong base ,the oxidation-reduction reaction take place intermolecular,the result is the oxidation product is a carboxylic acid salt and the reduction product is an alcohol
Step 1,nucleophilic attack of OH- on the carbonyl center
Step 2,get anion
Step 3,the anion attack another aldehyde ,transferring proton get acid and alkoxide ions
Step4,ecause of strong base,the final product is 苯甲酸盐和苯甲醇
装置图
The process
1\In the 125ml conical flask ,9g KOH,9g H2O,after dissolution add 10ml 苯甲醛，quickly shake ,get white paste substance
2\extraction separate ,add 30ml water ,dissolve the white paste substance ,pour inti separatory funnel with 10ml ether extraction ,twice ,keep the water layer ,
3\washing the ether layer ,step by step ,NaHSO3,NaCO3,H2O,washing ether ,remove impurity
4\water bath ,recovery ether ,then collect about 200 degree fraction ,(苯甲醛）
add about 5ml concentrated hydrochloric acid ,after cooling (苯甲酸)dissolve out ,filter .
Organic synthesis ---wolff-kishner -huang ming long reduction
Aldehydes or ketones in alkaline condition and react with hydrazine ,reduce to alkane ,that is carbonyl reduction to methylene ,
(机理在维基百科)
The method involved heating the hydrazine with sodium hydroxide about 180 degree,the solvent mostly use
Diethylene glycol
Reaction mechanism (维基百科)
The mechanism first involves the formation of hydrazine because of the condensation reaction ,between hydrazine and carbonyl ,under the effect of NaOH,the proton in the nitrogen takes off ,then double bond shift ,then bitrogen leave ,the formation of carbon negative ions take proton from water .eventually ,carbonyl reduced to methylene.
At first ,the wolf-kisher reduction choose Na metal to proceed the reaction which is expensive and difficult to be stored ,besides,the reaction take place must be in the sealing tube or the autoclave ,that means hard to operate
However ,the huang modification successfully solve these problem ,he choose the NaOH solution instead of Na ,greatly reduced the cost of materials,choose high bolling solvent such as diethylene glycol.so that do not need to react in the sealing tube ,it is easy to operate ,thirdly ,the productivity increase from 40%to 90%.
Tips :the temperature 180degree because the elimination of water and over NH2-NH2,reach the decomposition temperature of hydrozone
尝试下能不能发上
无机化学
中文要点
基本反映类型，酸碱中和，度分解反应
元素周期表
无机化学实验；酸碱滴定
英文概述
in my freshman year ,our teacher taught us this course by lecture .this is a study of elements, elementary substance and inorganic compound knowledge .i have learned the periodic table of elements ,the basic reaction type between inorganic compound .
For example ,neutralization replacement reaction
NaOH(aq)+ HCL ------NaCl (aq) +H2O
Zn +CuSO4(aq)---------- Cu +ZnSO4(aq)
At the same time ,we also use these principle to practical operation .such as ,measuring the unknown chloride ion concentration .it can be determined by titration with standard silver nitrate .choose the K2CrO4 as indicator .
Ag+ + Cl- -----------AgCl (white )
Ag+ + CrO4 2- -------------- AgCrO4 (red)
AgCl is white and is much less solute than AgCrO4 which is red .Formation of a red precipitate of AgCrO4 signs the end point of the titration ,
Tips :titration ,must into drops ,cannot into flow ,you should shake the conical flask gently for several times . Drop by drop .
物理化学
知识点 动力学，热力学，电化学，胶体
中文概述
1】 动力学 具有简单级数反应，计算以最简单为例，化学反应速率方程
2】 热力学 三大定律，熵，焓的概念，计算举例
3】 电化学 原电池，，电解池，阴阳极，正负极
4】 胶体 表面活性剂
英文概述
1、thermochemistry is the part of thermodynamic that deals with the relationship between chemical reaction and heat , we begin our study of thermodynamics with thermochemistry for two reasons ,heat is useful and heat is easy to measure . Some examples ,natural gas burns provide heat ,On a cols winter day water freeze to ice ,the burning of fuels supplies warmth in winter .
1、divide into two types ,exothermic ,changes in which the system gives off thermal energy ,like the burning of natural gas ,
Endothermic---changes in which the system absorb energy from the surroundings ,like ice melting ,change into water ,
2 enthalpy
Most changes in lab take place under constant pressure of earth atmosphere
The thermal energy gained or lost when a change takes place under constant pressure is called the enthalpy change .H
H= H(final ) -- H(initial )
Thermal energy given off can be shown as a product of the reaction in a thermochemical equation ,
CH4(g) +2O2(g)-------CO2 +2H2O(l) H=-890.32kj
One mole CH4 gas reacts with two mole of O2 gas .the products are one mole of CO2 gas ,two mole of liquid water ,and 890.32 kj of thermal energy ,the “-”sign for H shows that the reaction is exothermic .
3 entropy
Entropy is a thermodynamics property that is the measure of system thermal energy
Entropy change is only related with state ,has nothing to do with way ,
Entropy of a closed system always increase and in heat transfer situation ,heat energy is transferred from higher temperature components to lower temperature components .
4 三大定律的表述
Law one heat and work are forms of energy transfer ,energy is always conserved . Energy can be neither created nor destroyed ,however ,energy can change forms ,and can flow one place to another .U=Q--W.increase in internal energy equal heat supplied minus work done by the body ,
Law two : the German scientist Clausius statement : heat can never pass from a closer to a warmer body without some other change .occurring at the same time
Kelvin statement
No process is possible in which the sole result is absorption of heat from a reservoir and its complete conversion into work .
The second law defines entropy ,
The entropy of any isolated system not iin thermal equilibrium almost always increase
Law three :the entropy of a system approaches a constant value as the temperature approaches zero ,the entropy of a pure crystalline substance at absolute zero temperature is zero .
2\electrochemistry
Many oxidation -reduction reaction take place spontaneously .a device that use a spontaneous oxidation - reduction ,to produce an electric current ,such as ,Cu-Zn cell ,is called a voltaic cell .
加上简单的图解，就好。最基本那种什么阴阳极啊，之类的，
总反应式： Zn+Cu 2+ -------Cu（s）+Zn2+
The electrons move through the wire away from the anode towards cathode .current through the solutions consist of the movement of ions .
Zinc lose 2e-,become Zn 2+.Cu 2+get 2e-.become Cu ,
So anode Zn dissolve ,cathode Cu produce
Salt bridge keep the solution charge balance ,
The electrons move through the wire away from the anode towards the cathode ,
The device is changing the chemical energy into electrical energy
胶体sol
In disperse system ,the disperses substance called disperse phase ,another substance called disperse medium ,
When the disperse medium is liquid ,called sol ,like milk ,foam ,
When the disperse medium is solid ,called solidsol ,like pearl
When the disperse medium is gas ,called aerosol ,like frog
2 optical properties of sol ---tyndall effect
If let a beam of light through the sol .then look from flank .that is ,in the light move vertical direction ,you can see it forms a cone of light ,that is tyndall effect .it is often used to distinguish between sol and true solution .
理想气体状态方程
PV=NRT
Where p is the pressure od the gas ,v is the volume of the gas ,n is the number of moles of gas ,R is a proportionality constant ,and t is the kelvin temperature
The idea gas equation can be used to solve a variety of problems about gases ,if you know any three of four variables ,pvnt,you can calculate the unknown one by means of gas equation
波谱分析
1 ultraviolet visible spectroscopy
Produced by the outermost valance electron in molecules .in transition between different orbital energy level ,tell us the relationship between the energy change in the electronic transition ,and chromophore .
UV spectroscopy is used analytical chemistry for quantitative determination of different substance ,such as transition metal ions ,highly conjugated organic compounds
The beer-lambert law states that the absorbance of a solution is directly proportional to the concentration of the absorbing species in the solution and path length .
A=log(I0/I)=k cl
A is absorbance ,I0 is the intensity of the incident light at a given wavelength ,I is the transmitted intensity ,l is the path length through the sample ,and c is the concentration of the absorbing species ,k is a constant ,
2 infrared spectroscopy
Is the spectroscopy that deals with the infrared region of the electromagic spectrum ,that is wavelength 2-25 um ,of absorption spectroscopy .it can be used to identify and study chemicals.to get the information about the functional group of molecular . A common lab instrument that uses this techbique is FTIR spectrometer.the characteristic peak ,show us that the exsitance of a certain group ,and have a high strength or specific shape of the peak ,that is in the infrared spectrum ,the abscissa axis is wave number ,the ordinate axis is absorbance .like the absorption peak of ethene located in 1680-1620cm-1,
The calculation of degree of unsaturation
U=(2n+2+a-b)/2
E ,,n represent four valence ,like C,Si
E, a represent trivalence ,like N,P
E, b represent monovalence ,like H,Cl
3 nuclear magnetic resonance spectrometry
Is a physical phenomenon ,in a strong magnetic fields,nuclear energy level division take place ,absorbing extra electromagnetic radiation energy ,from low level transition to a high level ,that is NMR.and according to the NMR,we can know the detailed information about the structure ,reaction state and so on .
From HNMR,you can judge ,the H is alkyl hydrogen ,or alkene hydrogen ,or hydroxy ,
In HNMR,the abscissa is chemical shift represent the location of absorption peak ,the ordinate is the strength of absorption peak.
Some basic chemical shift
炔烃氢 1.6-3.4ppm
烯烃 4.5-7.5ppm
醛基 9-10.5ppm
羟基 0.5-5.5ppm
4 mass spectrometry
Is a kind of measuring ion charge -mass ratio ,analysis method can be used to analyze isotope composition organic matter structure and element composition
In high vacuum system ,test the samples of molecular ion and fragment ion mass ,to make sure the relative molecular mass of samples and molecular struchture ,
分析化学
Visible -spectrophotometry is a method ,make use of molecule substance on the selectivity of visible light ,to conduct quantitative determination .
Take visible spectrophotometer for example.Lightsource--(polychromatic)----monochromator---(monochromatic light)-- absorption cell ------detector ----computer
These are the major parts of spectrophotometer.
The light source provide polychromatic through the monochromator change into monochromatic light .put the bring tested absorption solution into absorption cell.when the monochromatic light oh I0 strength go through ,part of it be absorbed.
The transmitted light of It strength reach the detector ,the detector connect with computer ,after processed get A, according to beer-lambert law ,A=kbc,where A is absorbance ,b is the thickness of absorption cell,unit is cm ,c is amount-of-substance concentration ,the unit is mol/L,then the k is molar absorption coefficient .unit is L/(mol*cm)
By the experiment get A,after calculating ,get C.
滴定方法
Titration is a way of working out the concentration of a substance in solution ,under the condition of acidic ,KMnO4 react with H2O2,release O2 gas,the equation is
5H2O2+2MnO4-+6H+--------5O2+2Mn2++8H2O
Suppose that ,the concentration of kmno4is unknown ,take 25ml,into conical flask ,the acid burette filled with known concentration h2o2,then put the h2o2 into kmno4,drop by drop ,because kmno4 is dark purple ,so can be used as indicator.when titration ,the solution appears pink ,and do not fade in 30seconds.that is end point ,record the consumption volume.
Then according to the equation ,calculate c.
化学反应工程和化工原理
By learning chemical reaction engineering ,we have researched some problem about chemical kinetics and equipment type ,operation mode and catalyst and so on .
For operation mode and process,there are three basic types of reactor ,”batch reactor ””plug flow reactor ”and continuous stirred tank reactor .
Batch reactor , it consists of a tank with an agitator and complete heating/cooling system ,its characteristic is that the reaction`s materials are one time added into the reactor,then the reaction take place ,after a certain period of time ,when reach the required level of response ,the materials are unloaded from reactor.
Plug flow reactor
In a PFR, one or more fluid reagents are pumped through ,a pipe or tube ,the chemical reaction ,proceeds as the reagents travel through the PFR,in this type of reactor ,the reaction rates are changing ,at the inlet to the PFR the rate is very high ,but as the concentration of reagents decrease and the concentration of product increase ,the rates slows,on the flow direction ,there is no backmixing ,the residence time of materials in the reactor are all the same ,so some tubular reactor with small pipe diameter ,fast flowing rate and long pipe length can regard as PFR
Continuous stirred tank reator
In a CSTR,one or more fluid reagents are introduced into a tank reactor equipped with an impeller,at the same time ,the reactor effluent is removed ,the impeller stirs the reagents to ensure proper mixing .besides,the concentration of reagents and temperature every where in this reactor are all the average ,and the equal to the concentration and temperature at the exit ,
动力学
Chenmical kinetic
Is the study of rates of chemical reaction ,is includes investigation of how different experimental conditions can influence the rate of a chemical reaction and information about the reaction mechanism and transition states
The reaction rete define as how fast or slow a reaction takes place ,use the concentration of reactant reduce or product concentration rise in unit time to represent ,
The order of reaction comes from the equation of reaction rate ,for example ,the general reaction is aA+bB---cC+dD,the reaction rate is R,[A][B]represent the concentration of reactant ,k is reaction constant ,so the equation of this reaction rate is R=k[A]a[B]b, and the sum of a and b is called overall order ,
In simple order reactions ,reaction are categorized as zero-order ,first-order ,second-order ,third-order ,with different reaction order we can use the reaction rate to describe the relationship between the reaction time and reaction concentration .for example.zero-order reaction have a constant rate, its reaction rate has no relationship with the concentration of reactant ,like surface catalytic reaction .
Principle of chemical engineering
Mainly do the research on the production of the physical process ,object is divide into the process and equipment ,the study of unit operation that fluid transportation ,liquid mixing ,and heat transfer ,i have learned the key points as follows ,
1 gas and liquid are fluid ,divied into two classes ,one is incompressible fluid ,like liquid ;the other one is compressible ,like gas,
2 bernoulli principle ,describe fluid along a stable ,inviscid ,incompressible ,flow move behavior ,incompressible flow equation is
1/2V2+gz+P/(midu )= constant
Where V is the fluid flow speed ,and 1/2 V2means kinetic energy
Gz means potencial energy
P/(midu )means static pressure
That means the sum of all forms of mechanical energy is a constant ,that means the sum of kinetic energy ,and potencial energy and static energy is a constant
But in the practical application ,because of the viscosity of the liquid ,so in the flow process,some mechanical energy turn into heat energy ,(because of friction )
If we get the VPZ between two planes ,
We can calculate the loss of mechanism energy
3 centrifugal pump
Depends on the centrifugal force which produced by the impeller rotation to transport the liquid ,a centrifugal pump converts mechanical energy from a moving liquid ,a portion of the energy goes into kinetic energy of the fluid motion ,and some into potential energy represented by lifting the fluid ,to a higher altitude
From a figure we can see ,the centrifugal pump basic structure is made up of five parts ,impeller ,pump shaft pump body ,suction pipe ,discharge pipe .in the spiral casing pump body ,there are 6-12impellers fixed in pump shaft ,form a channel which can let the liquid flow ,
Motor drive the pump shaft ,the pump shaft drive the impller to rotate,liquid go inside the pump through suction pipe ,under the action of the centrifugal force ,the liquids are flung to the outmost of the impeller,along the channel ,then the liquid enter into the discharge pipe ,reached the required location
4\heat transfer
In the object interior ,or between objects ,as long as the temperature difference exist ,then heat will transfer from a high temperature ,to a low temperature ,there are three ,basic heat transfer mode ,that is ,heat conduction ,heat convection ,and radiation ,
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发表于 2012-12-10 23:58:12
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