化学实验报告英文版
Chemical Experiment Report
Introduction:
In this experiment, the aim was to investigate the effects of different concentrations of a reactant on the rate of a chemical reaction. The reaction between hydrochloric acid (HCl) and sodium thiosulfate (Na2S2O3) was chosen as the model system. The rate of this reaction can be determined by measuring the time taken for the solution to become opaque due to the formation of a precipitate of sulfur.
Materials and Methods:
1. Chemicals:
- Hydrochloric acid (HCl)
- Sodium thiosulfate (Na2S2O3)
- Distilled water
2. Apparatus:
- Beakers
- Stopwatch
- Measuring cylinder
- Glass rod
- Pipette
3. Procedure:
1. Prepare five different solutions of sodium thiosulfate with concentrations
ranging from 0.1 M to 1.0 M.
2. Label five beakers accordingly.
3. Measure 50 mL of each sodium thiosulfate solution using a measuring cylinder and pour into the respective beakers.
4. Add 10 mL of hydrochloric acid to each beaker simultaneously.
5. Start the stopwatch immediately after adding the acid and record the time taken for the solution to turn opaque.
6. Repeat the experiment three times for each concentration to ensure accuracy.
Results:
The following table presents the average time taken for the solutions to turn opaque at different concentrations of sodium thiosulfate:
Concentration (M) | Time taken (s)
-----------------|---------------
0.1 | 120
0.3 | 60
0.5 | 40
0.7 | 30
1.0 | 20
Discussion:
From the results, it is evident that as the concentration of sodium thiosulfate increases, the time taken for the solution to turn opaque decreases. This
indicates that the rate of the reaction between HCl and Na2S2O3 increases with increasing concentration of the reactant.
The reaction between HCl and Na2S2O3 is a precipitation reaction that produces sulfur as a product. The rate of this reaction depends on the frequency of collisions between reactant particles. Increasing the concentration of sodium thiosulfate increases the number of particles available for collision, thereby increasing the likelihood of successful collisions and faster reaction rates. Furthermore, the reaction is known to be first-order with respect to both HCl and Na2S2O3. This means that doubling the concentration of either reactant will result in a doubling of the reaction rate. This relationship is consistent with the observed decrease in reaction time with increasing concentration. Conclusion:
In conclusion, this experiment demonstrated the relationship between the concentration of a reactant and the rate of a chemical reaction. The results clearly showed that increasing the concentration of sodium thiosulfate led to a decrease in the time taken for the solution to turn opaque, indicating a faster reaction rate. This experiment highlights the importance of reactant concentration in controlling the rate of chemical reactions and provides a practical example of how reaction rates can be manipulated by altering reactant concentrations.
化学实验报告英文 Chemical Experiment Report Introduction: Chemical experiments play a crucial role in the field of chemistry as they allow scientists to observe and understand the behavior of various substances and their reactions. This report aims to present the findings and observations from a recent chemical experiment conducted in the laboratory. Experimental Procedure: The experiment focused on the synthesis of a compound through a series of chemical reactions. Firstly, the required chemicals were gathered, including reactants, catalysts, and solvents. Careful measurements were made to ensure the accurate mixing of the substances. The experiment involved several steps, each with specific reaction conditions and timeframes. The reactions were conducted in a controlled environment, maintaining a constant temperature and pressure. The progress of each reaction was monitored using various analytical techniques, such as spectroscopy and chromatography. Results and Observations: The experiment yielded fascinating results and provided valuable insights into the chemical properties of the substances involved. The reaction kinetics were carefully studied, and the reaction rates were determined. This information can be crucial in understanding the efficiency of the reaction and optimizing the
Preparation of n -bromobutane 一、Purpose 1、Study the principle and method of preparing n-butyl bromide from n-butyl alcohol by treatment with sodium bromide and concentrated sulfuric acid 2、Learn the technique of reflux with a gas trap apparatus and washing. 二、Principle n-Butyl bromide can be easily prepared by allowing n-butyl alcohto react with sodium bromide and concentrated sulfuric acid. Main reactions ： NaBr + H 2SO4 → HBr + NaHSO4 24 H SO 322232222CH CH CH CH OH HBr CH CH CH CH Br H O +???→+ Secondary reactions ： 24H SO 32223222CH CH CH CH OH CH CH CH=CH H O ???→+； ()24H SO 32223222222CH CH CH CH OH CH CH CH CH O H O ???→+ 24222H SO HBr Br SO H O +??→++ 三、Materials n-butyl alcohol ：4mL Sodium bromide ：5g Concentrated sulfuric acid ：2.5mL/6mL Anhydrous calcium chloride:0.5g 10% aqueous sodium hydroxide:5mL 四、Primary reagent And Product physical constants
求一篇英文的化学实验报告范文（ Chemistry Lab sample (This is one of my Chemistry 11 lab assignment。) Title: Cooling and Heating Curves of a Pure Substance Objectives: to investigate the cooling process for liquid paradichlorobenzene to investigate the heating process for solid paradichlorobenzene Materials: Apparatus: rin stand and ring support buret clamp bunsen burner; wire gauze with ceramic centre; test tube(18mm*150mm); beaker(400ml); 2 thermometers; lab apron; safety goggles. Reagent: paradichlorobenzene Procedure: Data and observations: So generally, its the data you record throughout the lab. Data table should be customized for each lab. Conclusion: Questions and follow-up questions: Answer any question assigned at the back of the lab After all, this is only a high school lab example. If you are looking for a university chem lab template, i guess it would be more spesific in details。 well, generally, it goes like that. you can write your own one as long as you think you make clear of what you do. Have fun with it. 求一份英文实习report(300字左右) 这是范文这学期是我任教的第一学期，我担任初一级七班，八班的英语教学。 由于教学经验颇浅。因此，我对教学工作不敢怠慢，认真学习，深入研究教法，虚心向前辈学习。 经过一个学期的努力，获取了很多宝贵的教学经验。以下是我在本学期的教学情况。 因此，了解和分析学生情况，有针对地教对教学成功与否至关重要。最初接触教学的时候，我还不懂得了解学生对教学的重要性，只是专心研究书本，教材，想方设法令课堂生动，学生易接受。
英文版的化学实验报告 英文版的化学实验报告 Introduction: Chemical experiments are an essential part of scientific research and education. They provide valuable insights into various chemical reactions and help us understand the properties and behavior of different substances. In this report, we will discuss the process and findings of a chemical experiment conducted to investigate the reaction between hydrochloric acid and sodium hydroxide. Experimental Procedure: 1. Materials: The materials used in the experiment included hydrochloric acid (HCl), sodium hydroxide (NaOH), distilled water, a burette, a conical flask, a pH meter, and a magnetic stirrer. 2. Preparation: A solution of hydrochloric acid was prepared by diluting a given volume of concentrated hydrochloric acid with distilled water. Similarly, a sodium hydroxide solution was prepared by dissolving a specific amount of sodium hydroxide pellets in distilled water. 3. Setup: The burette was filled with the sodium hydroxide solution, and the conical flask was placed on the magnetic stirrer. The pH meter was calibrated according to the manufacturer's instructions. 4. Titration: The hydrochloric acid solution was slowly added to the conical flask while stirring continuously. The pH meter was used to monitor the change in pH during the titration process. The addition of hydrochloric acid was stopped when
Title The title for the lab report may be provided by your lecturer. If not, you will need to make up your title. It should be brief, informative, and interesting. It is not usually a sentence. You should aim to provide just enough information in the title to avoid it being overly general. The key is to be concise and meaningful. Check with your lecturer if you need to include a title page and ensure all the relevant information is supplied. This will include your name, student number, date of the experime nt, the demonstrator’s name and the group you belong to. Introduction The introduction should be clear and concise. It should tell the reader what to expect in the report. An introduction generally includes the following elements: ? Problem – State the issue investigated by the experiment. ?Background –Briefly summarise previous research on the topic and narrow the scope of the study. ? Objectives – State the aim of the experiment and state the methods used. ? Hypothesis – If this is not already given, you must formulate this in unambiguous terms. The introduction is written in the past tense following the scientific style of writing. Materials and methods This section should contain a clear enough explanation of how you conducted the experiment so that someone wishing to replicate the procedure may be able to do so. Here you should describe the experimental design, the treatments and the apparatus you used. You should follow the rules for the conventional descriptions of chemicals. The standard practice is not to use trade names for chemicals. Instead you should use the generic or chemical names. Standard apparatus should be described in proper technical terms. Also, you should describe the procedures and methods of measurement you used. At the end of this section you should provide details of how you analysed the data. If this involved lengthy statistical calculations, these should be attached as an appendix. Results and discussion This section should be organised in a systematic way such that you first present the results and then discuss them. To report on results you should describe what happened. This is perhaps the most important section of your report because it is where you report the data upon which your conclusions are based. Accuracy, clarity of expression and systematic presentation of the data (e.g., use of tables, graphs, figures, diagrams, etc.) are key factors here. Take note that tables and figures do not simply repeat information given in the text –they are meant to summarise, amplify, or complement it. You should report first the results that bear directly on the title of your lab report. Any other interesting findings should follow this. If the experiment had more than one hypothesis, you may want to organise your results in a way that reflects this. A key
报告编号：YT-FS-8612-63 分析化学实验报告范文 (完整版) After Completing The T ask According To The Original Plan, A Report Will Be Formed T o Reflect The Basic Situation Encountered, Reveal The Existing Problems And Put Forward Future Ideas. 互惠互利共同繁荣 Mutual Benefit And Common Prosperity
分析化学实验报告范文(完整版) 备注：该报告书文本主要按照原定计划完成任务后形成报告，并反映遇到的基本情况、实际取得的成功和过程中取得的经验教训、揭露存在的问题以及提出今后设想。文档可根据实际情况进行修改和使用。 实验题目:草酸中h2c2o4含量的测定 实验目的: 学习naoh标准溶液的配制、标定及有关仪器的使 用; 学习碱式滴定管的使用，练习滴定操作。 实验原理: h2c2o4为有机弱酸，其ka1=5、9×10-2，ka2=6、 4×10-5、常量组分分析时cka1>10-8，cka2>10-8， ka1/ka2<105，可在水溶液中一次性滴定其两步离解的 h+: h2c2o4+2naoh===na2c2o4+2h2o 计量点ph值8、4左右，可用酚酞为指示剂。 naoh标准溶液采用间接配制法获得，以邻苯二甲
酸氢钾标定: -cook -cooh +naoh=== -cook -coona +h2o 此反应计量点ph值9、1左右，同样可用酚酞为指示剂。 实验方法: 一、naoh标准溶液的配制与标定 用台式天平称取naoh1g于100ml烧杯中，加50ml 蒸馏水，搅拌使其溶解。移入500ml试剂瓶中，再加200ml蒸馏水，摇匀。 准确称取0、4~0、5g邻苯二甲酸氢钾三份，分别置于250ml锥形瓶中，加20~30ml蒸馏水溶解，再加1~2滴0、2%酚酞指示剂，用naoh标准溶液滴定至溶液呈微红色，半分钟不褪色即为终点。
化学实验报告英文版 Chemical Experiment Report Introduction: In this experiment, the aim was to investigate the effects of different concentrations of a reactant on the rate of a chemical reaction. The reaction between hydrochloric acid (HCl) and sodium thiosulfate (Na2S2O3) was chosen as the model system. The rate of this reaction can be determined by measuring the time taken for the solution to become opaque due to the formation of a precipitate of sulfur. Materials and Methods: 1. Chemicals: - Hydrochloric acid (HCl) - Sodium thiosulfate (Na2S2O3) - Distilled water 2. Apparatus: - Beakers - Stopwatch - Measuring cylinder - Glass rod - Pipette 3. Procedure: 1. Prepare five different solutions of sodium thiosulfate with concentrations
薄层色谱实验报告英文版 Thin Layer Chromatography Experiment Report Introduction: Thin layer chromatography (TLC) is a widely used analytical technique in chemistry for separating and identifying different components of a mixture. It is a simple and quick method that involves the separation of compounds based on their polarity and their interaction with a stationary phase and a mobile phase. In this experiment, we used TLC to separate and identify the components of a mixture of food dyes. Materials and Methods: The materials used in this experiment were a TLC plate, a mixture of food dyes, a developing chamber, and a solvent system consisting of ethyl acetate and hexane in a 1:1 ratio. The TLC plate was first marked with a pencil line about 1 cm from the bottom. A small amount of the mixture of food dyes was spotted on the pencil line using a capillary tube. The TLC plate was then placed in the developing chamber with the solvent system. The solvent system was allowed to move up the plate by capillary action until it reached the top. The plate was then removed from the chamber and allowed to dry. The separated components were then visualized using a UV lamp. Results: The TLC plate showed the separation of the components of the mixture of food dyes. The components were identified based on their Rf values, which is the ratio
对氯苯氧乙酸的合成 一、 实验目的和要求 1、 掌握机械搅拌操作； 2、 学会对氯苯氧乙酸的合成方法； 3、 进一步熟悉亲核合成反应； 4、 熟练重结晶操作。 二、 实验内容和原理 对氯苯氧乙酸是植物生长调节剂的中间体，有许多合成方法，本实验采用Willamson 法进行合成。反应方程式如下： 副反应： 222ClCH COOH + NaOH HOCH COONa+NaCl+H O → 碘离子是比氯离子更好的离去基团，能够明显地提高S N 2反应的反应速率和产率，因此，使用催化量的KI 是必要的。在碱性条件下，苯酚生成苯酚负离子，可以明显提高它的亲核性，但在碱作用下，氯乙酸同样会发生水解反应，即被羟基负离子进攻生成副产物。本实验采用先将一部分NaOH 与苯酚反应，生成苯酚负离子，再分别滴加剩余的碱和氯乙酸，以减少氯乙酸的水解，提高反应的产率。 主反应机理： 副反应机理： 三、 主要物料及产物的物理常数 OH Cl + Na OH H KI −−−→−−→ OCH 2COOH Cl 2ClCH COOH +
四、主要仪器设备 仪器100mL三口烧瓶；滴液漏斗；电热包(或油浴装置)；机械搅拌器(或磁力搅拌器)；球形冷凝管；吸滤装置；250mL烧杯；10mL量筒；50mL量筒；胶头滴管。 试剂对氯苯酚；氯乙酸；20%NaOH；碘化钾；1:1盐酸；95%乙醇；pH试纸。 五、操作方法和实验步骤
实验装置图：
六、 实验结果与分析 重结晶前的粗产物质量为11.72g ，粗产率为 11.72100%124.2%6.50186.59/128.56/m g m g g mol M g mol M ⨯= =⨯粗产品 对氯苯酚 对氯苯氧乙酸 对氯苯酚 粗产率超过100%，显然其中混有大量杂质。根据实验过程分析，由于未趁热加酸，导致酸化不充分，粗产品抽滤时没有充分洗涤，这两个原因导致产物中混入大量对氯苯氧乙酸盐杂质。 重结晶提纯的产物经干燥后质量为4.76g ，产率为 4.76100%50.5%6.50186.59/128.56/m g m g g mol M g mol M ⨯= =⨯产物 对氯苯酚 对氯苯氧乙酸 对氯苯酚 提纯干燥产物的熔程两次测量分别为155.6℃~157.0℃，155.7℃~157.2℃，平均为155.6℃~157.1℃，比文献值157℃~159℃偏低，分析其原因可能为混入脱羧产物或(和)乙醇，或者干燥不充分所致。 七、 思考题 1、 为什么要在搅拌下滴加氯乙酸？ 答： 防止氯乙酸的瞬时浓度过大增加副反应的发生。 2、 为什么将对氯苯酚先溶于NaOH 溶液中，作用何在？ 答：在碱性条件下，苯酚生成苯酚负离子，可以明显提高它的亲核性，但在碱作用下，氯乙酸同样会发生水解反应，即被羟基负离子进攻生成副产物。本实验先将对氯苯酚溶于NaOH 溶液中，生成对氯苯酚负离子，再分别滴加剩余的碱和氯乙酸，以减少氯乙酸的水解，提高反应的产率。 八、 讨论、心得 1、 实验操作注意点 (1) 试管中的对氯苯酚加入适量NaOH 溶液适当加热后倒出，然后用少量NaOH 溶液洗涤试管。
竭诚为您提供优质文档/双击可除酵母菌发酵实验报告英文 篇一：发酵实验报告 实验报告 实验名称：与酵母菌发酵 所属课程名称：发酵工程工艺原理班级：20XX级生物技术组长：组员： 时间:20XX.11.27—20XX.12.3实验指导教师：黄循吟 海南师范大学生命科学学院 20XX年12月5日 摇瓶的应用与酵母菌发酵 摘要：发酵工程属于生物技术的范畴，是指利用微生物的生长繁殖和代谢活动来大量生产人们所需要的产品过程 的理论和工程技术体系，是生物工程和生物技术学科的重要组成部分。本实验 通过对酵母菌进行摇瓶培养,并定时取样测定其oD值、
ph和菌体数，制作菌体生长曲线，以此判断酵母菌的生长发酵状况。关键词：发酵、摇床、酵母菌一.目的 1.掌握酵母发酵工艺流程及其具体操作方法。 2.了解酵母菌的生长代谢的基本规律。二．原理 千百年来，人类几乎天天离不开酵母菌，例如酒类的生产，面包的制作，乙醇和甘油的发酵，本实验主要通过对酵母菌发酵过程中一些数值的测定，绘制其生长曲线，来了解酵母菌的生长状况。为获得实验相关数据，需对酵母菌进行培养，首先涂布平板28℃培养48小时后挑取单菌落进行斜面保存，再挑取斜面保存的菌种进行扩大培养，自扩大培养起，每三个小时取一次样，在oD505下测吸光度，在显微镜下观察，计算菌种数量当菌种数量达到108个/ml时（用血细胞计数板计数，以25个中方格的计数板为例，设5个中方格中的总菌数为A，菌液稀释倍数为b，则：1ml菌液中的总菌数=A/5*25*10＾4*b），即可进行发酵培养。自发酵培养起每三个小时取一次样，测其吸光度值、 ph值（用ph计测量）、菌种数量。结果整理：（1）以时间为横坐标。oD值为纵坐标作图。（2）对最终的发酵液进行离心，得湿酵母烘干，称干重，计算得率。最后对实验结果进行讨论和分析。三.材料与方法1．实验材料菌种：酵母菌2.培养基配方 分离培养基：黄豆芽100g，葡萄糖50g，水100ml，琼
篇一：英文版化学实验报告 Title: Preparation of Fe scrap from waste (NH4) The purpose of the experiment Learn the method used scrap iron preparation of ferrous ammonium sulfate. Familiar with the water bath, filtered, and evaporated under reduced pressure and crystallization basic working. The experimental principle, the iron and sulfuric acid to generate reactive ferrous sulfate, ferrous sulfate and ammonium sulfate in an aqueous solution of equal molar interaction, becomes less soluble blue generate ferrous ammonium sulfate. Fe+H2SO4=FeSO4+H2 (gas) FeSO4+ (NH4)2SO4+6H2O=(NH4) Usually ferrous rocks are easily oxidized in air, but after the formation of relatively stable perfunctory, not to be oxidized. Experiment to use instruments, scales, constant temperature water bath, pumps, basins, cups, 10ml graduated cylinder, asbestos mesh, glass, tripod, alcohol lamp, funnel. Iron pieces to a solid pharmaceutical use, use of acid ammonium sulfate and 3mol / l of sulfuric acid, concentrated sulfuric acid. The experiment was divided into four steps. The first step Said iron powder 4g into a beaker and then 50ml 10ml, 3mol / L H2SO4 was added to the same beaker. The second step will be the beaker is heated to no more bubbles, and then filtered hot and the filtrate was then filled in 100ml beaker. The third step, called 4g (NH4)2SO4, and the resulting ammonium sulfate and of water to form a saturated solution, and then add it to the ferrous sulfate solution, adjusted with concentrated sulfuric acid to PH = 1. A fourth step, the third step the solution was heated in a water bath to the surface until the film is crystallized, it was slowly cooled and
糖、氨基酸和蛋白质的鉴定 糖类化合物：又称碳水化合物，是多羟基醛或多羟基酮及其缩聚物和某些衍生物的总称，一般由碳、氢与氧三种元素所组成。 实验目的： （1）进一步了解糖的化学性质；（2）掌握鉴定糖的方法及其原理。 （一）-萘酚试验（molish)糖类化合物一个比较普遍的定性反应是molish 反应。即在浓硫酸存在下，糖与-萘酚(molish试剂）作用生成紫色环。 实验方法 取3支试管，编号，分别加入 ml %的各待测糖水溶液，滴入2滴molish 试剂（ -萘酚的乙醇溶液），摇匀。把试管倾斜450，沿管壁慢慢加入约1ml 浓硫酸（切勿摇 动），小心竖直后仔细观察两层液面交界处的颜色变化。硫酸在下层,试液在上层样品：葡萄糖、蔗糖及淀粉 解释: 糖被浓硫酸脱水生成糠醛或糠醛衍生物，后者进一步与 -萘酚缩合生成紫红色 物质，在糖液和浓硫酸的液面间形成紫色环。 （二） fehling试验 （1）实验原理 fehling试剂：含有硫酸铜和酒石酸钾钠的氢氧化钠溶液。 硫酸铜与碱溶液混合加热，生成黑色的氧化铜沉淀。若同时有还原糖存在，则产生黄色或砖红色的氧化亚铜沉淀。为防止铜离子和碱反应生成氢氧化铜或碱性碳酸铜沉淀，fehling试剂中需加入酒石酸钾钠，它与cu2＋形成的酒石酸钾钠络合铜离子是可溶性的络离子。 （2）操作方法 取4支试管，编号，分别加入fehling试剂i和ii 各。摇匀并置于水浴中微热后，分别加入5滴待测糖溶液，振荡后置于沸水浴中加热2 ~ 3min，取出冷却，观察颜色变化及有无沉淀析出。fehling试剂 i：称取 g硫酸铜溶于100 ml蒸馏水中, 得淡蓝色的 fehling试剂 i。
葡萄糖、果糖的旋光度测定 一、 实验目的和要求 1、 了解旋光仪测定旋光度的基本原理； 2、 掌握用旋光仪测定溶液或液体物质的旋光度的方法； 3、 了解葡萄糖和果糖的旋光性质； 4、 学习通过测定旋光度计算溶液含糖量的方法。 二、 实验内容和原理 只在一个平面上振动的光叫做平面偏振光，简称偏振光。物质能使偏振光的振动平面旋转的性质，称为旋光性或光学活性。具有旋光性的物质，叫做旋光性物质或光学活性物质。旋光性物质使偏振光的振动平面旋转的角度叫做旋光度。 许多有机化合物，尤其是来自生物体内的大部分天然产物，如氨基酸、生物碱和碳水化合物等，都具有旋光性。这是由于它们的分子结构具有手征性所造成的。因此，旋光度的测定对于研究这些有机化合物的分子结构具有重要的作用，此外，旋光度的测定对于确定某些有机反应的反应机理也是很有意义的。 测定溶液或液体的旋光度的仪器称为旋光仪，其工作原理见下图。常用的旋光仪主要由光源、起偏镜、样品管(也叫旋光管)和检偏镜几部分组成。 物质的旋光度与测定时所用溶液的浓度、样品管长度、温度、所用光源的波长及溶剂的性质等因素有关。因此，常用比旋光度[α]来表示物质的旋光性。 溶液的比旋光度与旋光度的关系为： []()t D c L α α= ⨯溶剂 式中[]t D α为比旋光度；t 为测定时的温度(℃)；D 表示钠光(波长λ＝589.3nm)；α为观测的旋光度；c 为溶液的浓度，以g·mL -1为单位；L 为样品管的长度，以dm 为单位。 如果被测定的旋光性物质为纯液体，可直接装入样品管中进行测定，这时，比旋光度可由下式求出： []t D d L α α= ⨯ 式中d 为纯液体的密度(g·mL -1)。 测定旋光度具有以下意义： 1. 测定已知物溶液的旋光度，再查其比旋光度，即可计算出已知物溶液的浓度。 2. 将未知物配制成已知浓度的溶液，测其旋光度，计算出比旋光度，再与文献值对照，作为鉴定未 知物的依据。 3. 由比旋光度可按下式求出样品的光学纯度(OP )。光学纯度的定义是：旋光性产物的比旋光度除以
化学实验报告英语 Chemical Experiment Report Introduction Chemical experiments play a crucial role in the field of science and technology. They provide valuable insights into the properties and behavior of various substances. In this report, we will discuss a series of chemical experiments that were conducted in a laboratory setting. The experiments aimed to explore the effects of different variables on the reaction rate and product formation. Experiment 1: Reaction Rate and Concentration In this experiment, we investigated the relationship between reaction rate and concentration. We prepared a solution of hydrochloric acid and sodium thiosulfate. By varying the concentration of sodium thiosulfate and keeping the concentration of hydrochloric acid constant, we observed the time taken for the solution to turn cloudy. As expected, we found that a higher concentration of sodium thiosulfate resulted in a faster reaction rate. This experiment demonstrated the importance of concentration in determining the rate of a chemical reaction. Experiment 2: Temperature and Reaction Rate Temperature is another crucial factor that influences reaction rates. To study this, we heated a solution of potassium permanganate and oxalic acid to different temperatures. We then measured the time taken for the solution to change color. The results showed that an increase in temperature led to a significant
肉桂酸的制备 一、 实验目的和要求 1、 学习肉桂酸的合成方法； 2、 掌握Perkin 反应的原理和应用； 3、 掌握回流操作； 4、 熟练水蒸汽蒸馏和重结晶操作。 二、 实验内容和原理 芳香醛和酸酐在碱性催化剂作用下，可以发生类似羟醛缩合的反应，生成α，β-不饱和芳香醛，称为Perkin 反应。催化剂通常是相应酸酐羧酸钾或钠盐，有时也可用碳酸钾或叔胺代替，典型的例子是肉桂酸的制备： 3CH COOK 6532653170180C H CHO+(CH CO)O C H CH=CHCOOH+CH COOH C ︒−−−−→ 碱的作用是促使酸酐发生烯醇化反应，生成乙酸酐碳负离子，接着碳负离子与芳醛发生亲核加成， 第三步是中间产物的氧酰基交换产生更稳定的β-酰氧基丙酸负离子，最后经β-消去产生肉桂酸盐。用碳酸钾代替乙酸甲，反应周期可明显缩短。反应机理如下： H 3CC O CCH O O O C O O 3CC O C O O 2 H H 3CC O CH 2 O C O CH 3 O O C O 3 O O -HCl O OH 虽然理论上肉桂酸存在顺反异构体，但Perkin 反应只得到反式肉桂酸(熔点133℃)。顺式异构体(熔点68℃)不稳定，在较高的反应温度下很容易转变为热力学更稳定的反式异构体。 肉桂酸可用于制备L-苯丙氨酸、用作冠心病药心可安的中间体，还可用于制造局部麻醉剂、杀菌剂、
止血药等；在香料工业用于制取苯基丙烯酸甲酯、乙酯和苯酯，用作食品、化妆品香料，有较好保香作用；用于农药工业生长促进剂、长效杀菌剂、果品蔬菜的防腐剂等；还用于生产感光树脂的主要原料乙烯基肉桂酸。肉桂酸是测定铀、钒及分离钍的试剂。 三、主要物料及产物的物理常数 四、主要仪器设备 仪器磁力搅拌器；球形冷凝管；回流装置；水蒸气蒸馏装置；抽滤装置；水循环真空泵；热水漏斗。试剂苯甲醛(新蒸)；乙酸酐(新蒸)；无水碳酸钾；氢氧化钠；浓盐酸；乙醇。 五、操作方法和实验步骤