英语句子分析例题

英语句子分析例题（共6篇）

1.英语句子分析例题 篇一

摘要： 1.John was so sleepy that he could hardly keep his eyes _________. A. open B. to be opened C. to open D. opening 分析：本题考查 keep+宾语+宾补 结构。此时宾补常为形容词、副词、介词短语、分词等，据乐加乐星级老师 乐加乐星级英语老师是通过层层筛选出来的，教学经验丰富，风格各有不同，点击进入课堂……[详细]

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1.John was so sleepy that he could hardly keep his eyes _________.

A. open B. to be opened C. to open D. opening

分析：本题考查“keep+宾语+宾补”结构。此时宾补常为形容词、副词、介词短语、分词等，据此可排除B、C项。根据题意“约翰困得眼睛都快睁不开了。”可知是“保持一种状态”，应用形容词作宾补;而不是持续发生的动作，不用现在分词。故答案为A。

2. I didnt hear the phone last night. I _____ asleep.

A. must be B. should have been C. must have been D. should be

分析：此题中“must + have + p.p”表示对过去的推断，虽未证实，但十分有把握，意为“一定”、“准是”;“should + have + p. p”表示过去该做而实际未做的事，含有后悔或责备的意味。根据前句语境，可能判断出C是正确的。

3. In the study, I found my son ______ at a desk, with his attention ______ on a book.

A. sitting; fixing B. sit; fixed C. sitting; to be fixed D. seated; fixed

分析：此题考查不定式与分词作宾补的区别以及短语fix ones attention的用法。因为强调found的动作与sit同时进行，而省去to的不定式sit作宾补表动作的完成，但sitting和seated皆可。第二空中，attention原为fix的逻辑宾语，所以应选fixed作宾补足语。故此题正确答案为：D。

4. -What made you so angry?

-_____. My girl friend promised to come at 7:00 , but she hasnt turned up yet.

A. Having kept waiting B. Being kept waiting

C. To be keeping waiting D. Being kept waited

分析：此题考查的动名词作主语的这一语法功能。使you生气的是女友让你一直在等候，而且回答部分作第一句中的主语，应用动名词或不定式来完成，所以应是 “keep sb. doing”被动语态的-ing形式。故此题正确答案为：B。

5. The murderer was brought in with his hands _________ behind his back.

A. being tied B. having tied C. to be tied D. tied

分析：本题考查分词作伴随状语。介词with后可接名词或代词再加分词，在句中充当伴随状语或定语。这时名词或代词与分词之间具有逻辑上的主谓关系;当为主动关系时用现在分词，当为被动关系时用过去分词。此题中的hands与tie明显是被动关系，故正确答案为D。

6. Shanghai is larger than _________ city in Africa.

A. other B. any other C. the other D. any

分析：本题考查形容词比较级的用法。此题的难度在于乍一看是考查形容词比较级形式表达最高级意义，容易误选B项。但比较级表达最高级之意时，所比较的对象应属于同一范畴，比较的范围要一致。此题比较的是中国的上海和非洲的城市，范围不同，故不能用any other。正确答案为D。

7. Not the director but the actors _____ what they can ______ money for the disabled.

A. want to do; collect B. wants to do; collect

C. want to do; to collect D. wants to do; to collect

分析：此题考查的是由not ...but...并列的短语作主语时，主谓一致的问题以及不定式作状语的功能。此句的谓语动词由but后面的actor决定，所以是复数形式。故删去B和D。第二空是do what they can to do sth. 这一结构的运用，其中can后省去do, 而不定式作目的状语。故正确答案为：C。

2.英语句子分析例题 篇二

一、选择典型例题, 帮助学生理解并掌握

在数学教学中, 准确选择例题类型对数学知识点的讲解是非常重要的. 一个选择合理的数学例题, 能够使学生对于数学知识点的理解与掌握更加透彻. 如果教师选择的数学例题不能够突出讲解的重点, 很容易让学生出现听不懂或思维混乱的后果, 不明白教师此时讲解的侧重点在哪里, 甚至在课堂上出现注意力不集中, 厌学等不良现象. 若选择的数学例题过于简单, 学生会产生“什么都会了”的心理, 不能正确认识自己对知识点的掌握程度, 在教师讲解的过程中出现不认真听、思想溜号、自大等不良现象. 若选择的数学例题偏难, 一些基础知识较弱的学生将会很难理解与掌握, 导致部分学生在数学课堂上完全听不懂, 久而久之, 原本数学基础相对薄弱的学生对数学丧失学习兴趣, 或者干脆放弃学习, 导致学生的数学成绩出现严重的分层化. 可见, 合理的选择数学例题的类型对于例题教学的模式应用是至关重要的. 数学例题的选择, 一定要具有基础性、典型性、代表性, 不可一味的追求难度与技巧, 应该由易到难有层次的进行讲解, 使得学生的听课思路清晰易懂, 利于掌握扎实的数学基础. 例如, 在讲解有理数乘法的运算律时, 应该紧扣本节课的知识重点, 在选择例题时, 要侧重运用乘法的交换律与结合律进行引导解题. 因学生对于乘法的运算定律都非常熟悉, 利用学生学过的知识过渡到本节课将要学习的有理数, 同时结合学生已经学过的非负数扩展到有理数, 让学生明白有理数的运算律与曾学过的乘法交换律与结合律是一样的. 这样一来, 学生对于新的知识会觉得很容易理解, 教师也能达到教学目标.

二、针对不同层次学生, 选择不同层次的数学例题

在初中数学课堂上, 由于受外界因素及学生个人原因的影响, 每个学生对数学基础知识的掌握程度以及理解程度是有差异的, 所以教师在课堂上对初中数学例题进行讲解的时候, 应该选择不同层次的数学例题, 满足不同程度学生对知识的需求, 并在学习数学这门学科中获得快乐与成功, 增加学生对数学学习的兴趣及自信心. 对于数学基础知识掌握较弱的学生, 教师在选择数学例题时, 需侧重较基础的题型, 不易太难, 当学生已经掌握并能合理运用时应该及时给予鼓励, 提高学生的兴趣并能够积极主动的学习数学. 对于数学基础知识掌握较强的学生, 在选择数学例题时要侧重典型及难度偏高的类型题, 此类题型可以吸引学生, 并让学生有一种想钻研的求知欲望, 在教师讲解时能够很容易抓住学生在课堂上的思想, 拓展学生的逻辑思维能力, 使原本占据中上等学生的数学成绩升入更高的层次. 这样一来, 在课堂上不同层次的学生通过相应的例题都能学到适合自己的基础知识, 并提高自己, 完成自己的学习目标, 进而在学习数学这门学科中取得优异的成绩.

例如, 关于一元二次方程的例题: ( 2x -1) 2= 5适用于数学基础较弱的学生, 此题有多种求解的方法, 可以让学生先用学过的因式分解法求解, 然后教师借助因式分解法主要讲解直接开平方法, 最后将两种求解方法的答案对比一下是否相符, 并比较此两种方法的不同处, 让学生对每种方法都能够有良好的认识, 达到完全掌握知识点的目的.

( m +1) x2+ 2x + 3 = 0问: 当m取何值时, 此方程有两个不相等的实数根, 这道例题是对于基础类型例题的延伸, 适用于数学基础较好的学生.

三、从学生的角度出发, 进行数学例题讲解

在初中数学的例题教学中常会出现这样的现象, 即在课堂上讲解的原题课后再让学生做一遍时, 很多学生做不出或者做错. 那么导致这种现象发生的最主要原因是教师在讲解例题时术语偏多, 根据自己的思维与对事物的理解度去讲解, 学生很容易在课堂上出现听不懂的现象, 对于教师讲解的知识点不能完全掌握, 即使能够掌握也不知如何运用知识点去解答. 所以, 在初中数学例题教学时, 应该抓住学生的心理及理解程度, 站在学生的角度去讲解, 这样一来学生便能很容易理解例题中涉及到的知识点, 并学会如何应用.

例如, 关于一元二次方程例题的求解, 很多学生往往在这个部分出现丢分的现象, 看似简单的一元二次方程, 想要完全掌握并不失分需要一定的耐心及技巧. 教师在对此类型例题的讲解时, 应引导学生认真审题, 尤其是运算符的改变, 首先观察一元二次方程的类型, 看能否转化成一般形式去求解, 因式分解法也是一种解题思路, 若两种求解方法都不适用再考虑其他求解方法.

总之, 受地区的文化差异及环境影响, 每个学校及班级学生掌握数学的基础大不相同, 教师应该将初中数学例题应用于实际中, 重视例题的讲解对初中数学教学的重要性, 掌握基本数学例题的教学模式, 进而提高学生的学习成绩.

摘要：对例题的教学, 是在初中数学教学中最重要的一个环节.有技巧地进行数学例题教学, 不但能够锻炼学生的逻辑思维能力, 还能培养学生的数学综合素质.本文从初中数学例题教学的模式出发, 更深入的阐述了其在教学中的广泛应用.

3.英语专业八级模拟试题练习例题 篇三

A magazines design is more than decoration, more than simple packaging. It expresses the magazines very character. The Atlantic Monthly has long attempted to provide a design environment in which two disparate traditions -- literary and journalistic -- can co-exist in pleasurable dignity. The redesign that we introduce with this issue -- the work of our art director, Judy Garlan -- represents, we think, a notable enhancement of that environment. Garlan explains some of what was in her mind as she began to create the new design:“ I saw this as an opportunity to bring the look closer to matching the elegance and power of the writing which the magazine is known for. The overall design has to be able to encompass a great diversity of styles and subjects -- urgent pieces of reporting, serious essays, lighter pieces, lifestyle-oriented pieces, short stories, poetry. We dont want lighter pieces to seem too heavy, and we dont want heavier pieces to seem too pretty.

We also use a broad range of art and photography, and the design has to work well with that, too. At the same time, the magazine needs to have a consistent feel, needs to underscore the sense that everything in it is part of one Atlantic world. The primary typefaces Garlan chose for this task are Times Roman, for a more readable body type, and Bauer Bodoni, for a more stylish and flexible display type (article titles, large initials, and so on). Other aspects of the new design are structural. The articles in the front of the magazine, which once flowed into one another, now stand on their own, to gain prominence. The Travel column, now featured in every issue, has been moved from the back to the front. As noted in this space last month, the word ”Monthly“ rejoins ”The Atlantic“ on the cover, after a decade-long absence. Judy Garlan came to the Atlantic in 1981 after having served as the art director of several other magazines.

During her tenure here the Atlantic has won more than 300 awards for visual excellence. from the Society of illustrators, the American Institute of Graphic Arts, the Art Directors Club, Communication Arts, and elsewhere. Garlan was in various ways assisted in the redesign by the entire art-department staff: Robin Gilmore, Barnes, Betsy Urrico, Gillian Kahn, and Lisa Manning. The artist Nicholas Gaetano contributed as well: he redrew our colophon (the figure of Neptune that appears on the contents page) and created the symbols that will appear regularly on this page (a rendition of our building), on the Puzzler page, above the opening of letters, and on the masthead. Gaetano, whose work manages to combine stylish clarity and breezy strength, is the cover artist for this issue.

1. Part of the new design is to be concerned with the following EXCEPT ______

A) variation in the typefaces.

B) reorganization of articles in the front.

C) creation of the travel column.

D) reinstatement of its former name.

2. According to the passage, the new design work involves ______

A) other artists as well.

B) other writers as well.

C) only the cover artist.

D) only the art director.

3. This article aims to ______

A) emphasize the importance of a magazine’s design.

B) introduce the magazine’s art director.

C) persuade the reader to subscribe to the magazine.

4.英语句子分析例题 篇四

TV Game Shows

One of the most fascinating things about television is the size of the audience. A novel can be on the “best seller” lists with a sale of fewer than 100,000 copies, but a popular TV show might have 70 million TV viewers. TV can make anything or anyone well-known overnight.

This is the principle behind “quiz” or “game” shows, which put ordinary people on TV to play a game for prizes and money. A quiz show can make anyone a star, and it can give away thousands of dollars in the U.S. and almost everyone watched them. Charles Van Doren, an English instructor, became rich and famous after winning money on several shows. He even had a career as a television personality. But one of the losers proved that Charles Van Doren was cheating. It turned out that the show s producers who were pulling the strings, gave the answers to the most popular contestants beforehand. Why? Because if the audience didn t like the person who won the game, they turned the show off. The result of this cheating was a huge scandal. Based on his story, a movie under the title “Quiz Show” is on 40 years later.

Charles Van Doren is no longer involved with TV. But game shows are still here, though they aren t taken as seriously. In fact, some of them try to be as ridiculous as possible. There are shows that send strangers on vacation trips together, or that try to cause newly-married couples to fight on TV, or that punish losers by humiliation them. The entertainment now is to see what people will do just to be on TV. People still win money, but the real prize is to be in front of an audience of millions.

1. TV can make a beggar world-famous overnight.

A. Right

B. Wrong

C. Not mentioned

2. The principle behind “quiz” and “game” shows is to put ordinary people on TV to play a game for prizes and money.

A. Right

B. Wrong

C. Not mentioned

3. Prizes and money are usually provided by TV stars and large companies for winners.

aR>A. Right

B. Wrong

C. Not mentioned

4. One of the TV personalities, Charles Van Doren was proved to be cheating by persuading the Show s producers to give him the answers beforehand.

A. Right

B. Wrong

C. Not mentioned

5. The huge scandal of cheating in TV game shows was not exposed until 40 years later in the movie “Quiz Show”.

A. Right

B. Wrong

C. Not mentioned

6. Nowadays game shows are not treated as seriously as they used to be.

A. Right

B. Wrong

C. Not mentioned

7. Winners of present-day TV game shows no longer get money from the shows.

A. Right

B. Wrong

C. Not mentioned

KEYS: ABCBBAB

PASSAGE 2

Dyslexia

As many as 20% of all children in the United Stated suffer from some form of the learning disorder called dyslexia.

Experts on dyslexia say that the problem is not a disease. They say that persons with dyslexia use information in a different way. One of the world s great thinkers and scientists Albert Einstein was dyslexic. Einstein said that he never thought in words the way that most people do. He said that he thought in pictures instead. The American inventor Thomas Edison was also dyslexic. Dyslexia first was recognized in Europe and the United States more than 80 years ago. Many years passed before doctors discovered that persons with the disorder were not mentally slow or disabled. The doctors found that the brains of persons with dyslexia are different. In most people, the left side of the brain-the part that controls language-is larger than the right side. In persons with dyslexia, the right side of the brain is bigger. Doctors are not sure what causes this difference. However, research has shown that dyslexia is more common in males than in females, and it is found more often in persons who are left-handed. No one knows the cause of dyslexia, but some scientists believe that it may result from chemical changes in a baby s body long before i

at is born. They are trying to find ways to teach persons with dyslexia. Dyslexic persons think differently and need special kinds of teaching help. After they have solved their problems with language, they often show themselves to be especially intelligent or creative.

1. One out of five American children suffers from dyslexia.

A. Right B. Wrong C. Not mentioned

2. Many great thinkers and scientists in the world are dyslexic.

A. Right B. Wrong C. Not mentioned

3. The first cases of dyslexia in Europe were discovered less than a century ago.

A. Right B. Wrong C. Not mentioned

4. The left side of the brain in a dyslexic person is bigger than the right side.

A. Right B. Wrong C. Not mentioned

5. Generally speaking, dyslexia is more common in left-handed males than in right-handed females.

A. Right B. Wrong C. Not mentioned

6. It is believed that dyslexia is related to the bad habits of a baby s mother.

A. Right B. Wrong C. Not mentioned

7. Dyslexic people often turn out to be intelligent or creative once they have learned to handle language properly.

A. Right B. Wrong C. Not mentioned

KEY：ACABACA

PASSAGE 3

Plants and Mankind

Botany, the study of pants, occupies a peculiar position in the history of human knowledge. We don t know what our stone Age ancestors knew about plants, but from what we can observe of preindustrial societies that still exist, a detailed learning of plants and their properties must be extremely ancient. This is logical. Plants are the basis of the food pyramid for all living things, even for other plants. They have always been enormously important to the welfare of people, not only for food, but also for clothing, weapon, tools, dyes, medicines, shelter, and many other purposes. Tribes living today in the jungle of the Amazon recognize hundreds of plants and know many properties of each. To them botany has no name and is probably not even recognized

aas a special branch of“ knowledge ” at all.

Unfortunately, the more industrialized we become the farther away we move from direct contact with plants, and the less distinct out knowledge of botany grows. Yet everyone comes unconsciously on an amazing amount of botanical knowledge, and few people will fail to recognize a rose an apple or an orchid. When our Neolithic ancestors, living in the Middle East about 10,000 years ago, discovered that certain grasses could be harvested and their seeds planted for richer yields the next season, the first great step in a new association of plants and humans was taken. Grains were discovered and from them flowed the marvel of agriculture: cultivated crops. From then on, humans would increasingly take their living from the controlled production of a few plants, rather than getting a little here and a little there from many varieties that grew wild and the accumulated knowledge of tens of thousands of years of experience and intimacy with plants in the wild would begin to fade away.

1. It is logical that a detailed learning of plants and their properties must be extremely ancient.

A. Right B. Wrong C. Not mentioned

2. People cannot survive without plants.

A. Right B. Wrong C. Not mentioned

3. Tribes living today in the jungle of the Amazon teach botany to their children at school.

A. Right B. Wrong C. Not mentioned

4. Our direct contact with plants grows with the process of industrialization.

A. Right B. Wrong C. Not mentioned

5. Today people usually acquire a large amount of botanical knowledge from textbooks.

A. Right B. Wrong C. Not mentioned

6. People living in the Middle East first learned to grow plants for food about 10,000 years ago.

A. Right B. Wrong C. Not mentioned

7. Once mankind began farming, they no longer had to get food from many varieties that grew wild.

A. Right B. Wrong C. Not mentioned

Key: AABBBAB

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5.英语句子分析 篇五

如：They were teachers.(他们曾是老师。) He enjoys singing songs. (他喜欢唱歌。) 这两句话分别由动词were (are 的过去式)，enjoys singing (enjoy doing动词短语)作谓语。其中were 体现出句子的时态为过去时态，且主语的人称为第一人称，enjoys singing 体现出句子的时态为一般现在时，且主语的人称为第三人称。

如：

I play with him. (我和他玩。) I like Chinese food.(我喜欢中国菜。)

这两句话中分别由人称代词 him ， 名词food 作宾语。

直接宾语与间接宾语：

有的动词能够接双宾语，直接宾语指的是动词所涉及的物,间接宾语是指受益于动词所表示行为的人。

如：He gave me a book.(他给了我一本书)

这句话中 a book 为直接宾语， me 为间接宾语。

又如：My mother bought a schoolbag to me.(我妈妈买了一个书包给我。)

这句话中schoolbag 为直接宾语， me 为间接宾语。

be 后是最常见如They were teachers.(他们曾是老师。) He is kind.. (他心地善良。)

这两句话分别由名词teachers， 形容词 kind

作表语。

这句话由相当于形容词的介词短语in the hospital 作后置定语，修饰work。

与定语的关键就是看其所修饰的部分，定语修饰名词，且起说明、限制作用。

如：The students study hard.(学生努力学习)

这句话由副词hard 作study的`状语。

又如： Pandas only live in China. (熊猫仅生活在中国。)

这句话由介词短语 in China 作live的状语。

再如：In the afternoon, I went to swim. (下午，我去了游泳。)

这句话由介词短语in the afternoon 作整个句子的状语。

限制性同位语中同位语与被它限定的词之间不用逗号隔开，非限制性同位语则用逗号隔开。 如： My uncle Mike is kind.(我的叔叔马克心地善良)

这句话中，Mike 作my uncle

的限制性同位语。

又如：He is interested in sports, especially ball games.(他对运动感兴趣，特别是球类运动。)

这句话中ball games 作sports 的非限制性同位语。

，属于独立成分。它的位置如： Sit down, Lucy.(露西，坐下)

这句话Lucy 为呼语

注意呼语与同位语的区别：同位语指一个名词(或其它形式)对另一个名词或代词进行修饰，

限定或说明，而呼语只是一个称呼。

如： My sister Lucy is very beautiful.(我的妹妹露西很漂亮。)

Lucy 为My sister 的同位语

又如： Lucy, come on.(露西，过来。)

Lucy为呼语

6.英语句子分析例题 篇六

高考化学计算型试题常用选择、填空、简答、全过程计算等基本题型, 分析近几年的高考计算题可以发现以下命题特点.

一、物质的多元性

题目涉及到物质的多组分, 造成研究对象头绪多、关系杂.准确掌握物质间的相互反应关系及根据化学方程式计算的知识是解题的基础.解题基本策略为:理清物质关系, 设元列式求解.

例1 将70 g Na2O和Na2O2的混合物全部溶于98 g 水中, 充分反应后, 所得溶液中NaOH的质量分数为50%.试求混合物中Na2O和Na2O2各多少克?

解析:由H2O+Na2O=2NaOH

2H2O+2Na2O2=4NaOH+O2↑

设Na2O和Na2O2的质量分别为 x、y, 则

$\{\begin{array}{l}x+y=70\text{g}\\ \frac{\frac{80x}{62}+\frac{80y}{78}}{70\text{g}+98\text{g}-\frac{16y}{78}}\times 100\%=50\%\end{array}$

解得$\{\begin{array}{l}x=31\text{g}\\ y=39\text{g}\end{array}$

答案:Na2O:31 g, Na2O2:39 g.

二、条件的隐含性

命题者有意将一些条件隐含起来, 增大了思维容量和试题难度.解题时要细琢题意, 化隐为现, 善于运用题外条件化远为近.

例2 设想有一带极薄隔板的容器, 在标准状况下向该容器的一侧充满NO和NO2, 向另一侧充满O2, 然后将该容器倒置于水中, 撤出隔板, 气体全部溶解.假设产物不扩散, 则容器内所得溶液的物质的量浓度 (c) 之大小范围为 ( )

(A) 0<c<1/22.4

(B) 1/39.2<c<1/22.4

(C) 1/28<c<1/22.4

(D) 1/39.2<c<1/28

解析:NO、NO2、O2和H2O可发生以下反应:

① 4NO2+O2+2H2O=4HNO3

② 4NO+3O2+2H2O=4HNO3

现忽略隔板的体积, 令容器的容积为VL, 假设该容器内只有NO2和O2, 则依题意和反应①知所得溶液的物质的量浓度为:

$c(\text{Η}\text{Ν}\text{Ο}{}_3)=\frac{4V/5}{22.4V}=\frac{1}{28}$

又假设该容器内只有NO和O2, 则依题意和反应②知所得溶液的物质的量浓度为:

$c(\text{Η}\text{Ν}\text{Ο}{}_3)=\frac{4V/7}{22.4V}=\frac{1}{39.2}$

综上可知, 所得溶液的浓度 (c) 的大小范围为1/39.2<c<1/28.

答案: (D) .

三、思维方法的多维性

思维能力是高考要求的四种能力的核心, 对思维能力多角度的考查是命题者刻意追求的.多年来的高考化学“压轴题”都表现了对思维方法和技巧越来越高的要求.

例3 黄铁矿主要成分是FeS2.某硫酸厂在进行黄铁矿成分测定时, 取0.1000 g 样品在空气中充分灼烧, 将生成的SO2气体与足量Fe2 (SO4) 3溶液完全反应后, 用浓度为

0.02000 mol/L的K2Cr2O7标准溶液滴定至终点, 消耗K2Cr2O7溶液25.00 mL.

已知:

SO2+2Fe3++2H2O=SO${}_4^{2-}$+2Fe2++4H+

Cr2O${}_7^{2-}$+6Fe2++14H+=

2Cr3++6Fe3++7H2O

(1) 样品中FeS2的质量分数是 (假设杂质不参加反应) .

(2) 若灼烧6 g FeS2产生的SO2全部转化为SO3气体时放出9.83 kJ热量, 产生的SO3与水全部化合生成H2SO4, 放出13.03 kJ热量, 写出SO3气体转化为H2SO4的热化学方程式:.

(3) 煅烧10 t 上述黄铁矿, 理论上产生SO2的体积 (标准状况) 为L, 制得98%的硫酸质量为t, SO2全部转化为H2SO4时放出的热量是kJ.

解析:本题综合考查了化学方程式的计算、能量的计算等.

(1) 由化学方程式可知:

3FeS2~6SO2~12Fe3+~12Fe2+~2Cr2O${}_7^{2-}$

所以样品中FeS2的质量分数:

$\frac{0.02000\text{m}\text{o}\text{l}/\text{L}\times 25.00\times 10{}^{-3}\text{L}\times \frac{3}{2}\times 120\text{g}/\text{m}\text{o}\text{l}}{0.1000\text{g}}$×100%=90%

(2) 灼烧6 g FeS2产生SO2的物质的量为:

$\frac{6\text{g}}{120\text{g}/\text{m}\text{o}\text{l}}\times 2=0.1\text{m}\text{o}\text{l}$

故生成SO3为0.1 mol, 所以1 mol SO3与水全部化合生成H2SO4, 放出的热量为

13.03 kJ/0.1=130.3 kJ.所以热化学方程式为:

SO3 (g) +H2O (l) =H2SO4 (l) ;

ΔH=-130.3 kJ/mol

(3) 煅烧10 t 上述黄铁矿, 理论上产生SO2的体积 (标准状况) 为:

$\frac{10\times 10{}^6\text{g}\times 90\%}{120\text{g}/\text{m}\text{o}\text{l}}\times 2\times 22.4\text{L}/\text{m}\text{o}\text{l}$

=3.36×107L

制得98%的硫酸质量为:

$\frac{\frac{10\text{t}\times 90\%}{120\text{g}/\text{m}\text{o}\text{l}}\times 2}{98\%}\times 98\text{g}/\text{m}\text{o}\text{l}=15\text{t}$

SO2全部转化为H2SO4时放出的热量是

$\frac{10\times 10{}^6\text{g}}{6\text{g}}\times (9.83\text{k}\text{J}+13.03\text{k}\text{J})=3.43\times 10{}^7$kJ

答案: (1) 90.00%

(2) SO3 (g) +H2O (l) =H2SO4 (l) ;ΔH=-130.3 kJ/mol

(3) 3.36×107 15 3.43×107

四、数学方法的技巧性

把化学问题抽象为数学问题, 利用数学工具, 结合化学知识, 通过计算, 解答化学问题, 是高考对化学的能力要求.近几年的高考化学“压轴题”都充分体现了这一能力要求, 解题时必须认真寻找化学规律, 熟练运用数学方法.

例4 在一定条件下, 将等体积的NO和O2的混合气置于试管中, 并将试管倒立于水槽中, 充分反应后, 剩余气体的体积为原气体总体积的 ( )

$(\text{A})\frac{1}{4}(\text{B})\frac{3}{4}(\text{C})\frac{1}{8}(\text{D})\frac{3}{10}$

解析:设NO和O2的物质的量均为 n, 则

2NO+O2=2NO2

3NO2+H2O=2HNO3+NO

由以上反应可知:n mol NO与 (n/2) mol O2反应生成 n mol NO2, 溶于水后得 (n/3) mol NO, (n/3) mol NO与 (n/6) mol O2反应生成 (n/3) mol NO2, 溶于水后得 (n/9) mol NO……不断循环反应下去, 总耗氧量为下列等比数列各项之和:$\frac{n}{2}‚\frac{n}{6}‚\frac{n}{18}\cdots$据等比数列的求和公式, 得总耗氧量为$\frac{\frac{n}{2}}{1-\frac{1}{3}}=\frac{3n}{4}$, 剩余O2为$n-\frac{3n}{4}=\frac{n}{4}$, 故剩余O2的体积为原气体总体积的1/8.

答案: (C) .

五、讨论问题的多样性

题目中只有制约条件而无“充足”的条件, 从而可产生多个结果, 解题时要全面的分析化学原理和制约条件, 详尽的讨论多种可能的情况, 得到正确答案.

例5 130℃时CO和某气态单烯烃的混合气体1L与9L (过量) 混合点燃, 充分反应后在压强不变、130℃时测得气体总体积为10L, 求该烯烃可能的分子式和它在混合气体中的体积分数.

解析:130℃时水为气态, 反应前后气体体积不变 (都为10L) .设单烯烃为CnH2n, 占 x L, 则有

$\text{C}{}_n\text{Η}{}_{2n}+1.5n\text{Ο}{}_2\stackrel{}{\to }n\text{C}\text{Ο}{}_2+n\text{Η}{}_2\text{Ο}$体积增大

1 0 .5n-1

x (0.5n-1) x

2CO+O2=2CO2 体积减少

2 1

1-x (1-x) 2

得: (0.5n-1) x= (1-x) /2

整理得: (n-1) x=1

据题意为气态单烯烃, 应在2≤n≤4的范围内讨论:

①当 n=2时, x=1, 与实际不符;②当 n=3时, x=0.5, 即C3H6, 占50%;③当 n=4时, x=1/3, 即C4H8, 占33.3%.

答案:C3H6, 占50%或C4H8, 占33.3%.

六、一题多解的灵活性

题目涉及的解题思路不止一个, 有“曲径”, 也有“坦途”, 但“殊途同归”.解题时要开拓思路, 避繁就简, 选取最佳解法.

例6 在硫酸铝、硫酸钾和明矾的混合溶液中, 如果SO${}_4^{2-}$离子浓度为0.2 mol/L, 当加入等体积的0.2 mol/L的KOH溶液时, 生成的沉淀恰好完全溶解, 则反应混合溶液中K+的浓度为 (假设溶液体积变化忽略不计) ( )

(A) 0.225 mol/L (B) 0.125 mol/L

(C) 0.45 mol/L (D) 0.25 mol/L

解法1:电荷守恒法:设硫酸铝、硫酸钾和明矾和混合溶液体积为1L.

据电荷守恒得:n (K+) +3n (Al3+) =2n (SO2-4) =2×0.2 mol/L×1L=0.4 mol.当加入1L KOH溶液生成的沉淀恰好完全溶解后, 变为K2SO4、KAlO2溶液, 据电荷守恒和原子守恒得:0.2 mol+n (K+) =0.4 mol+n (Al3+) , 则 n (K+) =0.25 mol, 所以, 反应后混合溶液中, n (K+) 总=0.25 mol+0.2 mol=0.45 mol, c (K+) 总=0.45 mol/2L=0.225 mol/L.

解法2:方程组法:设硫酸铝、硫酸钾和明矾的混合溶液中硫酸铝的物质的量为 x, 硫酸钾的物质的量为 y, 明矾的物质的量为 z, 溶液体积为1L.

由SO${}_4^{2-}$离子浓度为0.2 mol/L, 得:

3x+y+2z=0.2 mol ①

当加入等体积的0.2 mol/L的KOH溶液时, 生成的沉淀恰好完全溶解, 得反应:

Al3++4OH-=AlO-2+2H2O

加入的OH-为0.2 mol, 则Al3+为

0.05 mol, 得:

2x+z=0.05 mol ②

①×2+②×3, 得:2y+z=0.25 mol

则 n (K+) =0.25 mol+0.2 mol=0.45 mol

c (K+) =0.45 mol/2L=0.225 mol/L

解法3:终态判断法:设硫酸铝、硫酸钾和明矾的混合溶液体积为1L.

由题意知反应后溶液为K2SO4、KAlO2溶液.

Al3++4OH-=AlO-2+2H2O

加入的OH-为0.2 mol, 则AlO-2为

0.05 mol, 则

n (KAlO2) =n (AlO-2) =0.05 mol

n (K2SO4) =n (SO${}_4^{2-}$) =0.2 mol

得:n (K+) =n (KAlO2) +2n (K2SO4)

=0.45 mol

c (K+) =0.45 mol/2L=0.225 mol/L

解法4:中间产物判断法:设硫酸铝、硫酸钾和明矾的混合溶液体积为1L.

在硫酸铝、硫酸钾和明矾的混合溶液中, 加入0.2 mol/L的KOH溶液至生成的沉淀恰好完全溶解, 存在一个中间过程, 即Al3+恰好转化为沉淀, 此时为Al (OH) 3、KOH和K2SO4的化合物.

n (KOH) =0.2 mol× (1/4) =0.05 mol

n (K2SO4) =0.2 mol

n (K+) =n (KOH) +2n (K2SO4)

=0.45 mol

c (K+) =0.45 mol/2L=0.225 mol/L

解法5:变形化学式法:设硫酸铝、硫酸钾和明矾的混合溶液体积为1L.

将KAl (SO4) 2看成K2SO4·Al2 (SO4) 3, 则原混合溶液可看成K2SO4和Al2 (SO4) 3的混合液.据Al3++4OH-=AlO-2+2H2O, 加入的OH-为0.2 mol, 则Al3+为0.05 mol, Al2 (SO4) 3为0.025 mol, Al2 (SO4) 3中SO${}_4^{2-}$为0.075 mol.则K2SO4中SO${}_4^{2-}$为0.2 mol-0.075 mol=0.125 mol, K2SO4中K+为0.25 mol.

n (K+) =0.25 mol+0.2 mol=0.45 mol

c (K+) =0.45 mol/2L=0.225 mol/L

答案: (A) .

七、题型、信息的新颖性

题目情境新、设问巧是近几年高考化学试题的发展特点, 高考化学“压轴题”多是这一类题.解题时要善于分析、接受新信息, 灵活迁移解决新问题.

例7 美国“科学怪人”克雷格·文特尔2007年10月6日向媒体透露, 由他领导的研究小组合成了人类历史上第一个人造染色体, 并有可能创造出首个永久性生命形式.有一种式量为M的多肽, 经水解后只得到甘氨酸 (相对分子质量为75) , 如果该多肽是链状分子, 则一个这种多肽分子含有的肽键数为 ( )

$\begin{array}{l}(\text{A})\frac{{\rm M}-75}{57}(\text{B})\frac{{\rm M}}{75}\\ (\text{C})\frac{{\rm M}-18}{75}(\text{D})\frac{{\rm M}+18}{75}\end{array}$

解析:氨基酸含有氨基或羧基, 同种分子可以通过缩聚反应生成高分子化合物, 但是要区分清楚形成环状和链状时缩水数量的差异.设该多肽分子中有 n 个肽键, 已知每2个氨基酸分子脱1分子水形成二肽, 含有一个肽键, 依此类推, 含 n 个肽键, 需要 (n+1) 个甘氨酸分子脱 n 个水分子, 根据质量守恒:

(n+1) ×75=M+18n

解得:$n=\frac{{\rm M}-75}{57}$

答案: (A) .

山东省滕州市第一中学西校