【教育资料】第2单元课题二第2课时同步优化训练学习专用
第二单元《练习二》教案
第二单元《练习二》教案第二单元《练习二》教案第二单元《练习二》教案1教学内容:北师大版小学数学第十一册P31-33教学目标:1、通过练习，加强百分数的应用，能综合运用所学知识，解决问题。
2、进一步了解和掌握百分数的意义。
教学重点:进一步提高学生运用百分数解决实际问题的能力，体会数学与日常生活的密切联系。
教学过程十一、谈话引入。
同学们，我们学习了百分数的应用，现在来看看遇到这些问题，你会不会用所学知识去解决。
十二、基础练习1、P31练习二和第1题让学生先填表，然后指名说得数，集体订正。
2、第2题解方程，挑选几题有代表性的'题目，与学生一起探讨解题的方法。
3、练习二第3题（1）10月份比9月份节约用水百分之几是什么意思？（2）需要知道什么量？4、练习二第4题学生自主完成，集体订正师：什么叫孵化率？孵化率是95%是什么意思？不能孵出的占单位“1”的百分之几？1－95%=5%2400×5%=120（只）5、练习二第5题（1）先说题意，再独立完成。
（2）集体订正十三、提高练习。
1、（自主学习天地）请学生完成“智慧树”的题。
再分题集体订正，并说出解题思路。
2、课本练习二第11题（1）先让学生看统计表（2）分小组讨论完成题目（3）指名小组代表解答。
3、P33思考题师：要想知道哪个超市买更合算，先得求出分别到甲、乙超市买5瓶油的价格，再进行比较。
甲：12×4=48（元）买四送一，只需花4瓶的价格就可以买到5瓶油。
乙：12×5×0.85=51（元）每瓶12元，八五折师：八五折是什么意思？比较： 48<51所以选择去甲超市先让学生自主选择比较，再选择去哪个超市合算。
4、练习题（出示课件）学生独立完成。
四、课堂总结通过今天的学习你有什么收获？五、作业第二单元《练习二》教案2巩固除法的含义，及除法的各部分名称。
为后面学习用2～6的乘法口诀求商打基础。
教学过程设计：一、完成教科书第21页练习四第7题。
八级上册第二单元语文教案及同步练习人教版
5.题目：请举例说明在科学探究中如何进行问题解决。
答案：在科学探究中，问题解决是指通过科学探究的过程来解决实际问题的过程。例如，如果我们要解决某种植物生长不良的问题，我们可以通过提出问题、收集资料、分析资料、得出结论、验证结论的过程来解决这个问题。
八级上册第二单元语文教案及同步练习人教版
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授课教师
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授课班级
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教具
教材分析
本教案为人教版八级上册第二单元语文教案及同步练习。本单元的主题是“科学与探索”，通过本单元的学习，让学生了解科学探究的基本方法和过程，培养学生的科学素养和探究精神。本单元共包含3篇文章，分别是《试验与探究》、《观察与思考》、《分析与综合》。
教学实施过程
1.课前自主探索
教师活动：
-发布预习任务：通过在线平台或班级微信群，发布预习资料（如PPT、视频、文档等），明确预习目标和要求。
-设计预习问题：围绕“试验与探究”课题，设计一系列具有启发性和探究性的问题，引导学生自主思考。
-监控预习进度：利用平台功能或学生反馈，监控学生的预习进度，确保预习效果。
再次，在课后作业和拓展学习环节，我发现有些学生对作业的完成情况不理想，对拓展学习的兴趣也不高。这可能是因为我在布置作业和提供拓展资源时，没有充分考虑到学生的实际需求和兴趣。在未来的教学中，我需要更加关注学生的实际需求和兴趣，提供更具针对性和吸引力的作业和拓展资源，以提高学生的学习积极性和参与度。
学生活动：
2018年数学同步优化指导选修2-2练习：2-2-1 第2课时
第二章 2.2 2.2.1 第2课时1．分析法是( )A ．执果索因的逆推法B ．执因导果的顺推法C ．因果分别互推的两头凑法D ．逆命题的证明方法解析：由分析法的思想方法知，分析法是从结果入手寻求结果成立的充分条件，即执果索因的逆推法．故选A.答案：A2．欲证2－3＜6－7，只需要证( )A ．(2－3)2＜(6－7)2B ．(2－6)2＜(3－7)2C ．(2＋7)2＜(3＋6)2D ．(2－3－6)2＜(－7)2解析：∵2－3＜0，6－7＜0， ∴要证2－3＜6－7，只需证2＋7＜3＋6，即证(2＋7)2＜(3＋6)2.答案：C3．补足下面用分析法证明基本不等式ab ≤a ＋b 2的步骤． 要证明ab ≤a ＋b 2， 只需证2ab ≤a ＋b ，只需证________，只需证________，由于________显然成立，因此原不等式成立．解析：由分析法定义知．答案：a ＋b －2ab ≥0 (a －b )2≥0 (a －b )2≥04．如图所示，四棱柱ABCD －A 1B 1C 1D 1的侧棱垂直于底面，满足________时，BD ⊥A 1C (写上一个条件即可)．解析：要证BD ⊥A 1C ，只需证BD ⊥平面AA 1C . 因为AA 1⊥BD ，只要再添加条件AC ⊥BD ， 即可证明BD ⊥平面AA 1C ，从而有BD ⊥A 1C . 答案：AC ⊥BD (答案不唯一)5．已知a >b >0，试用分析法证明：a 2－b 2a 2＋b 2＞a －b a ＋b. 证明：要证明a 2－b 2a 2＋b 2＞a －b a ＋b(由a ＞b ＞0，得a －b ＞0)． 只需证(a 2－b 2)(a ＋b )＞(a 2＋b 2)(a －b )， 只需证(a ＋b )2＞a 2＋b 2，即2ab ＞0， 因为a ＞b ＞0，所以2ab ＞0显然成立．因此当a ＞b ＞0时，a 2－b 2a 2＋b 2＞a －b a ＋b成立．。
九年级人教版英语unit2第2课时
人教版九年级英语学科学 教教 案案课题Unit 2 I used to be afraid of the dark第二课时SectionA3a--4课型新授新授执笔人审核人学习目标1、知识目标：①单词airplane,terrify,on②短语be alone,speak in front of a group,be afraid of,go to sleep, be terrified of, with sth on③句子③句子I used to be afraid of dark.我过去害怕黑暗。
我过去害怕黑暗。
I’m terrified of the snakes.I’m terrified of the snakes.我害怕蛇。
我害怕蛇。
—Did you use to be afraid of being alone?你过去害怕独自一人呆着吗？你过去害怕独自一人呆着吗？—Yes, I did.是的，我怕。
是的，我怕。
I used to walk to school. 我过去走着上学。
我过去走着上学。
I used to go to sleep with the bedroom light on.过去我亮着卧室灯睡觉。
过去我亮着卧室灯睡觉。
2、能力目标：能够谈论自己过去与现在的情况能够谈论自己过去与现在的情况,,使用句型I used to be afraid of.3、情感目标：人是发展变化的，兴趣爱好也会较以前不同。
我们应该正确对待发展变化。
变化。
教学重难点一般现在时与一般过去时的区别；一般现在时与一般过去时的区别；be afraid/terrified ofbe afraid/terrified ofbe afraid/terrified of 的用法的用法的用法教学过程（一）预习展示1.1.独自一人呆着独自一人呆着独自一人呆着在众人面前说话在众人面前说话在众人面前说话害怕11 害怕害怕2呆在家呆在家…开着…开着…开着2.2.填空填空填空①. ---Did your sister use to have straight hair?---No, she used to have c__________ hair.②. Mr Green is really s__________, for he never smiles.③. Amy used to be quiet, but now she is very o__________.④. ---Did you u________ to play the piano? ---Yes, I did.⑤I used to be__________(real)quiet.<教学建议：教学建议：1.1.1. 预习展示部分由各组组长交换检查，并做好反馈记录预习展示部分由各组组长交换检查，并做好反馈记录（各组得分，错误较多的词组及疑难问题）。
第2单元课题二第1课时同步优化训练.pptx
解析：选 C。A 中将 FeCl3 滴入冷水不对；B 中生成棕黄色液体不对；D 中生成红褐色
沉淀不对。
4．要设计一套实验室利用液体和液体加热反应制备气体的装置，现设计了五步操作 ， 正确的程序是( )
③加入稀盐酸，使溶液呈强酸性，再加过量的 BaCl2 溶液。
④过滤，用蒸馏水洗涤沉淀。
⑤加热干燥沉淀物。
⑥将沉淀物冷却至室温后，称量。
⑦重复⑤⑥操作直到合格，最后得到 b g 固体。
回答下面问题：
( 1 ) 本实验中是否能用
：
Ba(NO3)2 代 替
BaCl2 ？
(2) 步 骤 ③ 中 加 盐 酸 使 溶 液 呈 强 酸 性 的
(3) 用 HCOOH 和浓硫酸制取 CO 气体中混有甲酸、水蒸气等气体杂质，因此可以用洗
气瓶除去，最后用排水法收集，结合(1)中的仪器，故不需要长颈漏斗。
(4) CO 有毒，但 CO 具有可燃性，多余的 CO 可用点燃的方法除去。 答案：(1)C (2)D (3)D (4)点燃
1．不．能用水浴加热的实验是( ) A ．苯的硝化反应 C．制酚醛树脂
。 答案：(1)防止 FeSO4 晶体析出 (2)趁热过滤 (3)保持溶液呈酸性、锥形瓶中与H2SO4 溶液反应的铁屑过量等措施 12．长期存放的亚硫酸钠可能会被部分氧化，现通过实验来测定无水亚硫酸钠试剂的纯
学海无 涯
度。实验步骤如下：
①称量 a g 样品，置于烧杯中。
②加入适量蒸馏水，使样品溶解。
两课时教案备课模板
两课时教案备课模板一、第一课时1. 教学目标：(1) 知识与技能：使学生掌握课程内容的基本概念和知识点。
(2) 过程与方法：通过自主学习、合作探讨等方式，提高学生对知识点的理解和运用能力。
2. 教学内容：(1) 课程内容的导入：通过问题引导、情境创设等方式，引起学生对课程内容的兴趣。
(2) 知识点讲解：详细讲解本节课的核心概念和知识点，确保学生理解。
(3) 案例分析：选取具有代表性的案例，让学生运用所学知识进行分析。
3. 教学活动设计：(1) 课堂导入：利用提问、情景创设等方式，激发学生的学习兴趣。
(2) 知识点讲解：采用讲解、互动问答等方式，确保学生掌握课程内容。
(3) 案例分析：分组讨论、小组展示等方式，培养学生的团队协作能力和分析问题能力。
二、第二课时1. 教学目标：(1) 知识与技能：巩固第一节课所学知识点，拓展相关知识。
(2) 过程与方法：通过实践操作、小组讨论等方式，提高学生的实际操作能力。
(3) 情感态度与价值观：培养学生的创新意识，提高学生的学习积极性。
2. 教学内容：(1) 课程内容的延续：针对第一节课的内容，进行拓展和深化。
(2) 实践操作：让学生动手实践，巩固所学知识。
(3) 小组讨论：分组讨论、分享心得，培养学生的团队协作能力和沟通表达能力。
3. 教学活动设计：(1) 课堂导入：通过问题引导、情境创设等方式，引导学生回顾上节课的内容。
(2) 知识点拓展：针对上节课的内容，进行拓展和深化，巩固学生所学。
(3) 实践操作：安排课堂练习或实验操作，让学生动手实践。
(4) 小组讨论：分组讨论、分享心得，培养学生的团队协作能力和沟通表达能力。
三、第三课时1. 教学目标：(1) 知识与技能：使学生掌握课程内容的基本概念和知识点。
(2) 过程与方法：通过自主学习、合作探讨等方式，提高学生对知识点的理解和运用能力。
2. 教学内容：(1) 课程内容的导入：通过问题引导、情境创设等方式，引起学生对课程内容的兴趣。
七下英语名师课时计划第二单元第二课答案
七下英语名师课时计划第二单元第二课答案全文共3篇示例，供读者参考篇1Unit 2 Lesson 2: A Bite of ChinaAnswer KeyHey guys! It's me again, ready to break down the answers for our latest English lesson. Unit 2 Lesson 2 was all about Chinese cuisine and food culture. As someone who really enjoys eating, this was a topic I could really sink my teeth into (pun totally intended)!Let's start with the pre-reading discussion questions on page 34. The first question asked what our favorite Chinese dishes are. For me, it has to be kung pao chicken - that perfect blend of spicy, savory, and a little bit sweet gets me every time. But I know everyone has their preferences when it comes to Chinese food. Maybe you're more of a fried rice person, or you go crazy for dumplings. There's just so much variety and flavor in Chinese cuisine.The second pre-reading question asked about any special food traditions or customs we know of in China. I wrote aboutthe importance of having a hot pot or other communal dish when celebrating holidays or special occasions with family. Sharing food from the same pot symbolizes unity and togetherness. But you may have learned about other fascinating traditions like only using chopsticks, or the cultural meanings behind certain lucky foods like dumplings.Okay, moving on to the reading passage itself on pages34-36 about the history and diversity of Chinese cuisine. I found the details about the different regional styles and influences really interesting. Like how Sichuan cuisine is known for being spicy, while Cantonese food has more mild and fresh flavors. It made me want to take a literal tour around China just to try all the local specialties!As for the comprehension questions following the passage, here are the key points I focused on in my answers:The answer highlighted how China's vast geography and many ethnicities contributed to the development of varied regional cuisines with unique ingredients and styles.I explained that the passage describes Chinese cuisine valuing the balance and harmony of different flavors and cooking techniques like frying, steaming, braising etc.For the third question, I discussed how the reading mentions the important role food plays in Chinese traditions and social life, such as banquets and family gatherings.Those comprehension questions really drove home how food is deeply woven into China's history, cultures, and way of life. It's not just about nourishment, but an entire experience shaped by the environment and values.For the post-reading discussion, the first question asked about our general impressions after learning more about Chinese cuisine's background. I shared how I have a newfound appreciation for the diversity and artistry involved. Every region's food seems to carry centuries of culinary heritage and traditions.The second discussion point asked if we would try cooking any of the dishes mentioned, like Peking duck or mapo tofu. Personally, I think it would be really fun (and challenging) to take a stab at making dumplings from scratch. But anything that requires too much precision with knives might be a disaster waiting to happen for me!Overall, this lesson made me hungry just reading and thinking about all the amazing Chinese dishes out there. It's incredible how food can open a window into understanding a country's culture, people, and ways of life. I can't wait toexperience it for myself someday through traveling and tasting my way across China!Phew, I know that was a lot, but I tried to cover all the key points as thoroughly as possible. Let me know if any part of the answer explanation needs some clarification. I'm always happy to go into more detail on topics that intrigue me, especially ones related to food! Until next time, happy studying!篇2Unit 2 Lesson 2 Answers by A StudentHey everyone! I'm here to share my answers and thoughts on the second lesson of our current unit. As usual, I'll break it down section by section. Let me know if you have any questions!Vocabulary:The vocabulary section focused on words related to occupations and workplaces. Some of the key words we learned were:Occupation - job or professionEmployee - someone employed by anotherEmployer - someone who employs othersWorkplace - the office, factory, etc. where someone worksCareer - the professional life/jobs of a personWe also covered specific job titles like doctor, teacher, engineer, chef, and many more. Building our vocabulary around this theme will be super useful for discussing future careers and jobs.Reading:The reading was pretty interesting - it was a few paragraphs describing different workplaces. The main offices/buildings it talked about were:A hospital - Where doctors, nurses, and other medical staff work to care for patientsA school - The workplace for teachers, principals, custodians etc. Where students go to learnA restaurant kitchen - The workplace for chefs, cooks, and food preparers. The fast-paced kitchen where meals are madeA corporate office - An office building where company employees like managers, accountants etc work atdesks/cubiclesA construction site - Where construction workers build structures like buildings and roadsThe reading compared and contrasted the environments, hours, uniforms/dress codes, and general responsibilities at each workplace. It was cool to think about how many different careers and jobs are out there.I made sure to underline any new vocabulary words I didn't know, like "pediatrician" (a doctor for children) and "contractor"(a construction worker hired for a specific project). Building my word bank in this topic will help me discuss and write about careers more effectively.Grammar:The grammar focus for this lesson was on modal verbs, specifically:Should/Shouldn'tCould/Couldn'tWould/Wouldn'tMust/Mustn'tWe looked at how these are used to express ideas like ability, permission, obligation and advice.For example:"You should study hard if you want to become a doctor.""Michael could not attend the meeting because he was feeling ill.""We must follow all safety protocols at the construction site.""You wouldn't be allowed on the job site without proper training and equipment."Using modals correctly to convey these meanings is crucial for speaking and writing clearly. The practice exercises helped cement using should/must for advice and obligations,could/would for ability and imagining situations, and mustn't for prohibitions.I still get a bit tripped up on choosing between could/would for hypothetical situations sometimes. But overall, I feel pretty solid on understanding and using modals now after this lesson.Writing:For the writing assignment, we had to describe our dream career and the workplace for that job. We were instructed to use modals and vocabulary from the lesson.Here's what I wrote:"My dream career is to become a world-famous chef and own my own prestigious restaurant. At my restaurant's kitchen, all employees must follow strict hygiene and food safety protocols. Chefs would need years of training and creativity to prepare the gourmet dishes on the menu. Customers should expect an exceptional, upscale dining experience when they visit.While the kitchen would be a high-stress, fast-paced environment, customers in the dining room couldn't see any of the commotion. Servers must treat every guest with polite, impeccable service. Customers shouldn't have to wait too long for their meals to be delivered promptly after ordering.To achieve my dream, I know I must pursue rigorous culinary training and work hard to distinguish myself from other chefs. I would need to save money carefully to be able to open my own restaurant eventually. It couldn't be an easy path, but I would feel immensely proud to one day be the head chef of anaward-winning establishment."I tried to hit on the key modal usage for advice(should/must), abilities (could/would), and prohibitions (mustn't/couldn't). I also wove in lots of vocabulary terms around occupations, workplaces, and the specific restaurant/kitchen context.Overall, this lesson provided excellent practical practice for using modals correctly in writing and speaking about careers. Building these language skills now will be hugely beneficial when it comes time for me to plan and pursue my own dream job down the road.Let me know if you need any clarification on these answers! I'm always happy to explain my thought process or address any areas I may have misunderstood. Looking forward to continuing to learn together.篇3Unit 2 Lesson 2 Answers by a 7th Grade StudentDear Classmates,I've been really struggling with the material in Unit 2 Lesson 2 of our English textbook this week. I find the topics and exercises quite challenging, so I spent a lot of time reviewing the lesson and want to share my understanding of the answers with all of you. Hopefully this helps clarify things!The lesson opens with a reading passage about two friends, Jessica and Sam, going on a hiking trip. There are some tricky vocabulary words to start off like "terrain", "navigate", and "gratifying". The questions about the main idea and supportingdetails are pretty straightforward - the main idea is that going hiking can be difficult but rewarding. Some key supporting details are the descriptions of the challenging landscape, Sam feeling tired partway through, but then their sense of accomplishment after reaching the summit.Where I really got tripped up was the questions analyzing the author's tone and use of language. I had to go back andre-read carefully to notice how the author uses vivid descriptive words like "rocky outcrops" and "winding trails" to paint a picture of the tough hiking conditions. And toward the end, words like "elated" and "gratifying" convey the positive tone of their sense of achievement. Paying close attention to an author's specific word choices is something I really need to work on.The writing exercise where we had to describe a place we've visited was pretty fun. I wrote about a trip to the beach, trying to use lots of descriptive language about the sights, sounds, and feelings there. My description probably could have used some more vocabulary variety beyond just words like "sandy" and "wavy". I'll have to review that for next time.Then we get into the grammar focus on past tense verbs. Whew, I have a hard time keeping straight when to use the simple past like "hiked" versus the past progressive like "washiking". I made a lot of silly mistakes on the practice exercises identifying and writing those correctly. From what I understand, you use the simple past for completed events in the past, and the past progressive for events that were ongoing at a point in the past. So "Jessica and Sam hiked to the summit" but "They were hiking for three hours before they reached it". Is that right? Let me know if I'm still mixing those up.The lesson also went over the past perfect tense, which feels like a total mind-bender to me. Using "had" plus the past participle indicates something had already happened before another event in the past. Like "By the time they reached the peak, they had already drunk all their water." I can never seem to get this straight, so I just try to avoid using the past perfect when writing myself. Maybe some more targeted practice will help it click.Lastly, we looked at using sequence words like "first", "next", "then", "finally" to clearly show the order of events. This makes total sense to me for when we're relating a narrative or story with a sequence of steps. The practice exercise was writing about the procedures to make a peanut butter and jelly sandwich, making sure to use sequence words precisely. Easy enough, though I got marked off for leaving out crucial steps like getting theingredients or the actual spreading of the peanut butter and jelly! I'll have to be more thorough next time.Phew, I know that was a marathon overview, but I really wanted to get all my thoughts down about this lesson's material while it's still fresh. Let me know if any part of my understanding is off-base or if you have any other tips for improving on these concepts. This unit is definitely pushing me, but I'm trying my best to master it all. Thanks for letting me share!Your Classmate。
八年级物理上册第2章2运动的描述第2课时快与慢习题课件新版教科版0928580
13、He who seize the right moment, is the right man.谁把握机遇，谁就心想事成。2021/9/82021/9/82021/9/82021/9/89/8/2021 14、谁要是自己还没有发展培养和教育好，他就不能发展培养和教育别人。2021年9月8日星期三2021/9/82021/9/82021/9/8 15、一年之计，莫如树谷；十年之计，莫如树木；终身之计，莫如树人。2021年9月2021/9/82021/9/82021/9/89/8/2021 16、教学的目的是培养学生自己学习，自己研究，用自己的头脑来想，用自己的眼睛看，用自己的手来做这种精神。2021/9/82021/9/8September 8, 2021 17、儿童是中心，教育的措施便围绕他们而组织起来。2021/9/82021/9/82021/9/82021/9/8
You have to believe in yourself. That's the secret of success. 人必须相信自己，这是成功的秘诀。
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高中化学选修6同步训练1．人的胃液是一种强酸性液体，pH在0.9～1.5之间，氢氧化铝是一种治疗胃酸过多的胃药的主要成分。
目前这种胃药已不常用，原因主要是()A．长期摄入铝元素不利于人体健康B．它不能中和胃酸C．它不易溶于胃酸D．它的疗效太差解析：选A。
铝元素在人体内积累过多，可使人记忆力减退、智力低下、行动迟缓等。
2．下列离子方程式书写正确的是()A．铝粉投入到NaOH溶液中：2Al＋2OH－===2AlO－2＋H2↑B．AlCl3溶液中加入足量的氨水：Al3＋＋3OH－===Al(OH)3↓C．三氯化铁溶液中加入铁粉：Fe3＋＋Fe===2Fe2＋D．FeCl2溶液跟Cl2反应：2Fe2＋＋Cl2===2Fe3＋＋2Cl－解析：选D。
离子反应方程式必须符合反应原理，A应为2Al＋2H2O＋2OH－===2AlO－2＋3H2↑；氨水是弱碱不能写成离子形式，B错；离子方程式必须符合质量(原子个数)守恒和离子总电荷守恒，所以C错。
3．下列物质中各含有少量的杂质，能用饱和Na2CO3溶液并借助于分液漏斗除去杂质的是()A．苯中含有少量甲苯B．乙醇中含有少量乙酸C．溴苯中含有少量苯D．乙酸乙酯中含有少量的乙酸解析：选D。
乙酸能与Na2CO3溶液反应，且乙酸乙酯在Na2CO3饱和溶液中的溶解度较小，易于分层。
4．实验室制乙酸乙酯1 mL后，沿器壁加入紫色石蕊试液0.5 mL，这时石蕊试液将存在于饱和碳酸钠溶液层与乙酸乙酯层之间(整个过程不振荡)。
对可能出现的现象，叙述正确的是()A．石蕊层仍为紫色，有机层无色B．石蕊层为三层环，由上而下是红、紫、蓝C．石蕊层有两层，上层为紫色，下层为蓝色D．石蕊层为三层环，由上而下是蓝、紫、红解析：选B。
乙酸乙酯与水互不相溶，且密度比水小，当加入紫色石蕊试液时，乙酸乙酯在上层，石蕊试液在下层，由于不振荡，所以石蕊与饱和Na2CO3溶液仅接触未混匀，由于Na2CO3水解使溶液呈碱性，故接触面上的颜色为蓝色。
而上层的乙酸乙酯中含乙酸杂质，使接触面上的石蕊试液显红色。
而石蕊试液中间没有反应，仍显紫色。
5．某课外小组设计的实验室制取乙酸乙酯的装置如下图所示，A中放有浓硫酸，B中放有乙醇、无水醋酸，D中放有饱和碳酸钠溶液。
已知：①无水氯化钙可与乙醇形成难溶于水的CaCl2·6C2H5OH；请回答：(1)若用同位素18O示踪法确定反应产物水分子中氧原子的提供者，写出能表示18O位置的化学方程式：________________________________________________________________________________________________________________________________________________。
(2)球形干燥管C的作用是______________。
若反应前向D中加入几滴酚酞，溶液呈红色，产生此现象的原因是(用离子方程式表示)________________________________________________________________________；反应结束后D中的现象是________________________________________________________________________。
(3)从D中分离出的乙酸乙酯中常含有一定量的乙醇、乙醚和水，应先加入无水氯化钙，分离出________；再加入________(此空从下列选项中选择)，然后进行蒸馏，收集77 ℃左右的馏分，以得到较纯净的乙酸乙酯。
A．五氧化二磷B．碱石灰C．无水硫酸钠D．生石灰解析：(1)中考查了酯化反应中浓硫酸的作用及同位素示踪法表示酯化反应的机理。
(2)中综合考查了盐类的水解(CO2－＋H2O HCO－3＋OH－)和酯化反应的可逆性及饱和Na2CO3溶液在制取乙酸乙酯时的作用。
(3)根据题给信息“①无水氯化钙可与乙醇形成难溶于水的CaCl2·6C2H5OH”说明加入无水氯化钙可除去乙醇。
蒸馏中加入的成分，既要考虑吸收水，又要与乙酸乙酯不反应。
故选C。
答案：(2)冷凝蒸气，防止倒吸CO2－3＋H2O HCO－3＋OH－溶液分层，上层为无色油状液体，下层溶液颜色变浅(3)乙醇 C1．以下实验能获得成功的是()A．乙醇和乙酸混合共热制取乙酸乙酯B．将铁屑、溴水、苯混合制溴苯C．在苯中滴入浓硝酸制硝基苯D．将铜丝在酒精灯上加热后，立即伸入无水乙醇中，铜丝恢复成原来的红色解析：选D。
A制取乙酸乙酯，应将乙醇和乙酸、浓硫酸三者混合加热；B应注意溴苯是在Fe作催化剂，由液溴和苯混合制得；C在苯中滴入浓硝酸和浓硫酸的混合酸后水浴加热才能制得硝基苯；铜丝在酒精灯上加热后生成CuO，CuO可把乙醇氧化为乙醛，自身被还原成红色的铜，故D正确。
2．下列除杂质的方法不．可行的是()A．用过量氨水除去Al3＋溶液中的少量Fe3＋B．将混合气体通过灼热的铜网除N2中的少量O2C．用新制的生石灰，通过加热蒸馏，以除去乙醇中的少量水D．用盐酸除去AgCl中少量的Ag2CO3解析：选A。
加过量氨水，由于Al(OH)3不溶于氨水，所以Al3＋和Fe3＋都会有沉淀析出，无法达到除杂要求。
3．A是一种常见的单质，B、C为中学学习的常见化合物，A、B、C均含有元素X。
它们有如下转化关系(部分产物及反应条件已略去)：下列判断正确的是()A．X元素可能为AlB．X元素可能是金属，也可能是非金属C．反应①和②互为可逆反应D．反应①和②一定为氧化还原反应解析：选D。
A为单质，B、C为化合物。
所以①②一定为氧化还原反应，所以D正确；A不可能为金属，因为金属无负价；①②不互为可逆反应，因为反应条件不同。
4．酯类物质广泛存在于香蕉、梨等水果中。
某实验小组从梨中分离出一种酯，然后将分离出的酯水解，得到了乙酸和另一种化学式为C6H13OH的物质。
以下分析不．正确的是()A．C6H13OH分子中含有羟基B．C6H13OH可与金属钠发生反应C．实验小组分离出的酯可表示为CH3COOC6H13D．不需要催化剂，这种酯在水中加热即可大量水解解析：选D。
酯的水解需要催化剂，而且是可逆反应。
5．利用下列装置(部分仪器已省略)，能顺利完成对应实验的是()解析：选D。
A项制乙酸乙酯时导管末端不应插入液面以下，否则容易发生倒吸；B项制备氢氧化亚铁时胶头滴管应插入液面以下，否则氢氧化亚铁容易被氧化为氢氧化铁；C项石油的蒸馏装置中温度计的水银球应放在蒸馏烧瓶的支管口附近；D项实验室制乙烯装置正确。
6．某物质在酸性条件下可以发生水解反应生成两种物质A、B，且A和B的相对分子质量相等，该物质可能是()A．甲酸乙酯B．乙酸乙酯C．葡萄糖D．淀粉解析：选A。
甲酸和乙醇的相对分子质量都是46。
7．下列除杂质的方法正确的是()①除去乙烷中少量的乙烯：光照条件下通入Cl2，气液分离②除去乙酸乙酯中少量的乙酸：用饱和碳酸钠溶液洗涤，分液、干燥、蒸馏③除去CO2中少量的SO2：气体通过盛饱和碳酸钠溶液的洗气瓶④除去乙醇中少量的乙酸：加足量生石灰，蒸馏A．①②B．②④C．③④D．②③解析：选B。
①乙烷中混有少量乙烯应用溴水(或溴的四氯化碳溶液)进行洗气。
若按题目叙述在光照条件下通入Cl2，不仅会引入新的杂质，而且会反应掉主要的物质乙烷。
②因乙酸能与饱和碳酸钠溶液反应而乙酸乙酯在饱和碳酸钠溶液中的溶解度较小，因此②是正确的。
因为CO2会与碳酸钠溶液反应：CO2＋H2O＋Na2CO3===2NaHCO3，从而使主要物质CO2消耗，应用饱和碳酸氢钠溶液除去，因此③是错误的。
若乙醇中混有少量的乙酸，加入生石灰后会反应掉杂质乙酸和新生成的水，再利用蒸馏可以得到纯净的乙醇，所以④是正确的。
8．甲、乙、丙、丁分别是Al2(SO4)3、FeSO4、NaOH、BaCl2四种物质中的一种，若将丁溶液滴入乙溶液中，发现有白色沉淀生成，继续滴加则沉淀消失，丁溶液滴入甲溶液时，无明显现象发生，据此可推断丙物质是()A．Al2(SO4)3B．NaOHC．BaCl2D．FeSO4解析：选D。
由“若将丁溶液滴入乙溶液中，发现有白色沉淀生成，继续滴加则沉淀消失”这一现象可知，丁为NaOH溶液，乙为Al2(SO4)3溶液，BaCl2和FeSO4两种物质中与NaOH溶液不反应的是BaCl2，所以丙为FeSO4。
9．某化学小组为测定一定质量的某铜铝混合物中铜的质量分数，设计了如下实验方案：方案Ⅰ：铜铝混合物―————―→足量溶液A充分反应测定生成气体的体积 方案Ⅱ：铜铝混合物―————―→足量溶液B 充分反应测定剩余固体的质量 下列有关判断中不．正确的是( ) A ．溶液A 和B 均可以是盐酸或NaOH 溶液B ．若溶液B 选用浓硝酸，则测得铜的质量分数偏小C ．溶液A 和B 均可选用稀硝酸D ．实验室中方案Ⅱ更便于实施解析：选C 。
在常温下，铝既可溶于强酸，又可溶于强碱，且都产生H 2，而铜则不能，铜只能溶于强氧化性酸，如与HNO 3反应可产生NO 2或NO ，因此溶液A 和B 均可以是稀盐酸、稀硫酸或NaOH 溶液，但不可选HNO 3，故A 项正确；若采用方案Ⅰ，由关系式2Al ～3H 2求出w (Al)进而求出w (Cu)，若采用方案Ⅱ，铝溶解，而Cu 不溶，则称量剩余固体质量即为m (Cu)，显然测量固体质量较测定气体体积更易操作，便于实施，D 选项正确；若溶液B 选用HNO 3，由于铝在浓硝酸中钝化，生成了致密的氧化膜，故所测得的固体质量实际上是铝和部分氧化铝的质量，此数据比混合物中铝的质量大，故得出的铜的质量偏小，w (Cu)偏小；溶液A 选HNO 3产生NO 2或NO ，气体不纯，不便计算。
10．某化学兴趣小组用回收的镁铝合金制取氢气。
现有10.8 g 镁铝合金，下列说法正确的是( )A ．常温下与足量18 mol/L H 2SO 4溶液反应，最多可放出0.6 mol H 2B ．常温下与足量2 mol/L HNO 3溶液反应，最少可放出0.45 mol H 2C ．常温下与足量2 mol/L H 2SO 4溶液反应，放出H 2的物质的量在0.45～0.6 mol 之间D ．常温下与足量2 mol/L NaOH 溶液反应，放出H 2的物质的量在0.45～0.6 mol 之间 解析：选C 。
A 、B 中的浓硫酸、硝酸均为氧化性酸，不能与镁铝合金反应产生氢气；NaOH 溶液只能与铝反应生成氢气，D 错；利用极值法可求得放出氢气量的范围为0.45～0.6mol 。
11．如图在试管甲中先加入2 mL 95%的乙醇，并在振荡下缓慢加入2 mL 浓硫酸，充分摇匀，冷却后再加入2 g 无水乙酸钠(CH 3COONa)。