5.下列原子结构示意图中，表示带两个单位正电荷的离子的是

A.　　　　　　　 　　　B.　　　　　　　　　 　C.　 　　　　　　　　D.

4.下列关于燃烧现象的描述中正确的是

　A.木炭在空气中燃烧后，生成黑色的固体　　　 B.硫粉在氧气中燃烧，产生大量白烟

　C.镁条在空气中燃烧，发出耀眼的白光 　　　　D.红磷在空气中燃烧，产生蓝紫色火焰

3.盛放酒精的试剂瓶的标签上应印有下列警示标记中的

2.石油没有固定的沸点，炼油厂根据石油中各成分沸点不同，将其分离开来，得到汽油、 煤油、柴油等。由此推断石油属于

A.单质　　　　　　 B.混合物　　 C.纯净物　　　　 D.化合物

1.下列现象中发生化学变化的是

A.纸张燃烧　 B.玻璃破碎　 C.冰雪融化　 D.酒精挥发

1. --This green coat looks nice on you and it is only 200 Yuan. --OK.______. A. I'll need it　 B . I'll take it　C. It's much too expensive.　 D. I'd like to sell it.　 2.　He left ______any of his friends _____ him _____. A. with; seeing; off　B. without; seeing; off　C. without; see; /　D. with; see; out 3.　______ is _____ the students to find out the meaning and the usage of new words. A. What a dictionary does; help　　B. What dictionary does; to help C. How a dictionary does; help　　D. All that a dictionary does; helps　 4.　The landowners in India would not vote to lose their land and wealth, _____ it resulted ______ a fairer society. A. even if; in　B. even though; of　C. as if; in　D. whether; of 5.　Towards _____ evening, _____ heavy rain began to fall. A. the; a　B. /; a　C. /; the　D. the; /　 6.　--Do you have _____ more to get in the market? --No, only some bread and butter. A. something　B. everything　C. nothing　D. anything 7.　The teacher as well as her students _____ to visit the Moter Company tomorrow. A. go　B. are to go　C. is to go　D. is about to go.　 8.　The building is _____. A. twenty-metre-high　　B. twenty metre high C. twenty-metres-high　　D. twenty metres high　 9.　The book ____ three Yuan, but it only ____ me two Yuan. A. spends, take　B. costs, spend　C. costs, cost　D. pays, cost　 10.　They are____ the same size. You can take ______ half of the bread. A. in, either　B. with, either　C. in, both　D. at, none　 11.　--Hello. May I speak to Mr. Wang, please?　　　　 -- _______. A. Hold the line. please　B. Wait for a minute　C. Here it is　D. Here he is　 12.　You can choose _____ book you like among these. A. no matter what　B. whatever　C. whose　D. whichever　 13.　This kind of paper was as soft and light as silk but ______ expensive. A. much less　B. much little　　　 C. many less　D. much more than　 14.　It had rained for several days. The clothes had _____ near the fire to dry. A. hang up　B. to hung up　C. to be hung up　D. to be hanged up　 15.　The line is engaged. I can't _____ now. A. get on　B. get along　　　 C. get through 　D. get down　 16. We should prevent pollution ________ happily. A. to live　　B. for living　　C. from living　D. living　 17. As we all know, ______ knowledge comes from _______ practice. A. the; the　B. a; a　　C. the ;×　D. ×; × 18. Sports build the body _______ reading builds the mind. A. while　　B. when　　C. as　　D. for 19. The mother ________ her son's success in the newspaper. A. learned about　B. learned　　C. heard　　D. learned from 20. "Don't forget to come to my birthday party tomorrow." "__________." A. I don’t'　B. I won't　　C. I can't　　D. I haven't　 21. She was given the chance to ______ designing the new bridge. A. take part in　B. attend　C. go all out　D. join 22. Don't read ______ books ________ you can not understand. A. same…as　B. the same …like　C. such …as　D such… like 23. Bob: How long have you lived here?　　Sue: _________. A. Since the beginning of the year.　　B. In 1990 C. Not long ago　　　 　　　 D. Only until the end of the year　 24. Do you mind _______ alone at home? 　 A. Jack's being left　B. Jack leaving　C. Jack having left　D. Jack to be left　 25. Mary realized she ______. A. was playing a joke about　　B. was making fun C. was being made fun of　　　D. was made fun　 26. Peter: Do you want a ride? Dick: _______ Peter: I asked if you wanted a ride? A. I don't mind.　　　B. I beg your pardon? C. I'll take a taxi.　　　D. I don’t' want a ride.　 27. _______ the manager? A. Who is in place of　　　B. Who is in the place of C. Who shall take the place of　　D. Who will take place of　 28. Mary: What do you think of my new dress? Sue: ________. A. It is on sale　　　B. You really have a new dress C. It looks very good on you　　D. I think it's a birthday present for you 29. Patty: How about going for a walk? Nancy: ________. A. I'll walk with you at eight　　B. That's not a bad idea C. Walking is a kind of exercise　　D. It will take me minutes to have a walk　 30. I found him _________ in an armchair, ___________. A. sit…and read　B. seated…reading　C. sitting…and read　 D. seating…reading 31. If you don't turn up by 8 o'clock, we'll go ______ you. A. without　B. except　　C. but　　D. besides 32. --Has Jane arrived yet?　　　　 --No, she_______ an hour ago. A. was supposed to come　　B. must have come C. should come　　　D. ought to have come　 33. _______ in time, little Franz was afraid. ________ scolded. A. Not having come…of being　　B. Having not come…to be C. Having not come…of being　　D. Not having come…to be 34. No one but Rose and Kate _______ a fine red coat. A. put on　　B. is wearing　C. dresses　D. have on　 35. The battle lasted for a few hours and at last the enemy ________. A. was defeated　B. were beat　C. were won　D. defeated　 36. He is not a man easy ______. A. to deal　　B. to deal him　C. to deal with　D. to deal with him 37. Mr. Li is gaining _______. He has to do some exercises to lose _______.　 A. weighty…weigh　B. weight…weight　C. fat…weigh　D. weighty…heavy 38. The clock ________ and we realized it was five o'clock. A. hit　　B. beat　　C. struck　　D. run　 39. Reading without stop is a ______ piece of work. A. tire　　B. tired　　C. tiresome　D. troubled　 40. He was afraid there was any wild animal around him, looking round from ________. A. time to a time　B. time to time　C. a time to a time　D. times to times　 41. It ________ that there is no way out of difficulty. A. looks　　B. thinks　　C. believes　D. seems 42. We were told that it was our _______ to read the text together. A. action　　B. turn　　C. absence　D. sign 43. --Why doesn't he buy you a drink? --I don't know why, but it isn't _______ he had no money. A. even if　　B. as if　　C. that　　D. because 44. What way are you thinking of _______ rid of this kind of pollution? A. to get　　B. get　　C. getting　　D. got 45. The angry boss ________ from the chair and went directly to him. A. lifted　　B. raised　　C. rose　　D. carried　　 46. The schoolboy regretted _______ after he didn't pass his exam. A. the time on TV　　　B. to spend so much time on TV C. taking most of his time on TV　D. spending so much time on TV　 47. Have you found his name ______ in the papers? A. signing　B. signed　　C. to sign　　D. sign　　 48. Since we have met again after all these years, let's ________ each other from now on. A. keep up with　B. keep out of　C. keep in touch with　D. keep touching　 49. The ______ in the mountain village struck most of the visitors. A. scenes　　B. space　　C. absence　　D. flight　　 50. It is difficult for you to ______ what will happen in space without gravity. A. depend on　B. have some idea of　C. keep from　　D. equip with　 51. The two brothers carried a ______ bed into the room. A. double　　B. deal　　C. slight　　D. opposite　 52. The accident ______ for a new car. Because the old one was destroyed. A. sent me looking　B. made preparations　C. kept me from looking　D. was fit　 53. --How is it that you are late for class again?　　　　　　 --________. A. By bus and then on foot　　B. It's quite all right C. Because I missed the bus　　D. It's far from school　　　 54. Hearing the sound of shots, the birds flew away ______ all directions. A. at　　B. for　　C. from　　D. in　 55. _______ the normal condition, he can read 150 words a minute. A. Below　　B. Under　　C. With　　D. In　　 56. Tom is good boy and _______ he is honest. He never tells a lie. A. at all　　B. in all　　　 C. above all　　D. after all　　 57. Many facts proved that long before Columbus ________ America, Chinese had visited it. A. noticed　B. uncovered　　　 C. discovered　D. arrived　　 58. The meeting was _______. Many people were for our plan. A. a success　B. success　　　 C. succeed　　D. failure　 59. --How much is it ______?　　　　　　 --$ 20, I think. A. spent　　B. cost　　　 C. worth　　D. taken　 60. The world is _______ seven continents and four oceans. 　 A. made up of　B. made out of　C. made from　D. made in　 61. --Can I help you? --I'd like to have my package ______, madam. A. be weighed　B. to be weighed　　 C. to weigh　　D. weighed　 62. I'm so busy that I can't ______ the time for a holiday at present. A. spare　　B. share　　　 C. spend　　D. take　 63. They would _______ for Guangzhou the next morning and so they went to bed early. A. set out　B. set about　　　 C. set up　　D. set to　 64. He insisted on his ______ Dr Turner instead of Mr. Turner. A. called　　B. calling　　　 C. being called　D. been called 65. John: _________ Jack: In two weeks. John: Are you going to Japan? Jack: No. I'm going to Australia. I went to Japan two years ago. A. How long have you been here?　　B. When is your holiday? C. When are you leaving for Australia?　D. How long do you plan to stay here? 66. Mary ________ passing the entrance examination. A. succeeded　　　B. succeeded in C. succeeds in　　　D. succeeds　 67. Tell the child not to drink _______ water. A. boiled　　B. boil　　C. boiling　　D. boils　 68. i set _________ tomorrow on my journey to America. A. on　　B. up　　C. to　　　D. out 69. The shop owner would _______ his money every day. A. count　　B. count for　C. count out　　D. counting　 70. The old lady devoted her lifetime _______ the homeless children. A. to help　　B. to helping　C. helping　　D. for help　 71. Tom: Would you like me to water your plants while you're on your holiday? Joe: ________ A. No problem. I was more than glad to do it. B. I appreciate it, but I'm already finished watering them. C. Thanks for offering your help, but my brother's going to do it. D. Certainly watering plants is my favorite pastime.　 72. --Don't you think it's going to rain over the weekend? --_______. A. I don't believe　B. I don't believe it　C. I believe not so　D. I believe not　 73. I knew I should not accept anything from such a person but I found it difficult to turn down his ___. A. plan 　　B. offer　　C. suggestion　D. request 74. --Do you mind my taking this seat?　　　　 --________. A. Yes, sit down please　　B. No, of course not C. Yes, take it please　　D. No, you can't take it　 75. How I envy you _______ your good luck!　 A. in　　B. of　　C. to　　D. /　　 76. This event was rather unusual, ________? A. is it　　B. isn't it　　C. was it　　D. wasn't it　 77. We have _______ books in our library. A. plenty of　B. great many　C. a great deal of　D. great number of 78. The police saw the woman _______ a bus and _______ a taxi. A. get off …get on　　B. get on … get off C. get off …get into　　D. get on … get into　 79. Do you mind ______ how you succeed? A. if I go and see　B. if I go seeing　C. my going and see　D. my go to see 80. The boy would have died, _______ on him without delay. A. if the doctor didn't operate　B. if the doctor wouldn't operate C. would the doctor not operate　D. had the doctor not operated 81. Only when ______ in 1918, ______ happily back to work. A. the war was over … he went　B. was the war over … did he go C. the war was over … did he go　D. was the war over … he went　　 82. --Who telephoned just now? --Sorry. I couldn't ______ the voice. A. recognize　B. realize　C. know　　D. understand　　 83. He had ______ in finding Mr. Green's house. A. many difficulties　　B. many difficulty C. much difficulties　　D. much difficulty 84. I don't want to _______ money on such books. A. cost　　B. pay　　C. spend　　D. take 85. --Thank you for your help.　　　　　 --________. A. All right　B. That's right　C. You're right　D. That's OK　 86. The man is standing _______ his back _______ the fire. A. with … to　B. with … against　C. on …for　D. at … of 87. I looked everywhere in the house ______ a key that had been lost. A. in searching for　　B. in search of C. to search　　　D. searching of 88. I insisted that he_______ at once. A. leave　　B. left　　C. leaves　　D. leaving　 89. When will you _______ me the money that was borrowed? A. pay　　B. repay　　C. pay for　　D. repay for　 90. "Do you have any clothes to ______, Tom?" mother asked. A. wash　　B. washing　C. be washed　D. washed　 91. You may use the book as you like, _______ you keep it clean. A. unless　　B. so long 　C. as long　　D. so long as　 92. He ________ the world record. A. failed to break　B. failed to breaking　C. failed breaking　D. failed broken 93. No ________ what you say, _______exists in three states. A. matter…matters　　　B. matter…matter C. matters…matter　　　D. matters…matters　　 94. I wonder what time lunch is_______ in your school. A. given　　B. taken　　C. served　　D. eaten　　 95. The people in some countries ________ freedom. A. longed　B. long for　C. longing　　D. longing for　 96. I ______ all the bookshops in our town for the book I needed but I couldn't get one. A. hunted　B. found　　C. looked for　　D. searched for　 97. A piece of ______ music will make you happy. A. fond　　B. pleased　C. merry　　D. glad 98. --You seem to get lost. Need help? -- _______ A. Yes, would you please help me with the bag? B. Help me find my key, please. C. Yes, give me a hand, please. D. I'm looking for Zhongshan Road.　 99. --I must apologize for _______ ahead of time. --That's all right. A. letting you not know　　B. not letting you know. C. letting you know not　　D. letting not you know　 100. The students are well _______ the exam. They are sure to get good marks. A. prepared for　B. ready for　　C. prepared　　D. preparing　 101. Yesterday the president spoke on TV to the _______. A. country　B. nation　　C. land　　D. state　 102. The nurse gave ________ the sweets to the children. A. up　　B. off　　C. out　　D. in 103. Remember to______ a stamp on the envelope before you post it. A. put　　B. place　　C. strike　　D. stick　 104 John: Do you happen to have twenty dollars with you? Jack: _______ John: I want to buy a notebook. A. How do you want it?　B. How much? C. What for?　　　D. When can you pay me back?　 105. After school was over the boys ________ their books and went home. A. put in　　B. put aside　　C. put away　　D. put up 106. _______ went to see the film yesterday. A. Every of them　　　B. Both they C. Nobody of them　　　D. Not all of them　　 107. The higher the birds flew, _______ we could see them. A. less clearly　　　B. the less clearly C. more clear　　　D. more clearly　　 108. With her long beautiful hair gone _______ would be no use for the combs. A. she　　B. they　　C. there 　　D. it.　 109. Joe: Why don't you tell me a few things about your country? Ken: __________ A. Because I can't tell you many things at a time　B. I'm afraid I can't. C. Sure. What in general are you interested in?　D. I don’t know anything about that.　 110. --You look so worn-out! --i lay ________ all the night. A. woke　　B. awake　　C. slept　　D. asleep 111. When you ______ the book please return it to the library on time. A. get through　B. get along　　　 C. look through　D. look up 112. Both the man and his horse ________ after the long ride. A. gave out　B. worn out　　C. tired out　D. run out　 113. You _______ last night, but you went to the concert. A. must have studied　　　B. might study C. should have studied　　D. would study　　 114. Teacher: You can't finish the book in less than an hour, I suppose? Student: __________. A. Yes, I'm sure I can　　　B. No, hardly C. Sorry, I can't　　　D. I don't think I can　　 115. Tom: My brother will be surprised when he opens this package I'm sending. Jack: Why are you sending him a package? Tom: __________. A. It's a new radio　　　B. It's his birthday C. It's very expensive　　　D. It's too late 116. "Have a nice weekend!" " _________." A. The same to you　　　B. You do too C. The same as you　　　D. You have it too　 117. Joe: Are you taking some gifts with you when you return to America? Dan: I'm planning to do so. Have you any suggestions? Joe: __________. A. I'm leaving tomorrow　　　B. I'm taking a plane C. Why don't you buy some bamboo works?　D. I posted them to America yesterday 118. ―What happened to the old mail carrier? ―He _______ to a new neighborhood to work. A. has sent 　B. has been sent 　C. was sent 　D. sent 119. Mary: This handbag isn't yours, is it? Joan: __________. A. Yes, it's not mine　　B. No, yours is bigger C. Yes, it's my friend's　　D. No, mine is a red one　 120. "Hi, haven't seen you for ages! You look fine!" "__________. You look well, too." A. Great　　B. Thanks　　C. Oh, no　　D. Not at all　

40．(09年山东理综·28)(14分)运用化学反应原理研究氮、氧等单质及其化合物的反应有重要意义。

(1)合成氨反应N₂(g)+3H₂(g)2NH₃(g)，若在恒温、恒压条件下向平衡体系中通入氩气，平衡　　　 移动(填“向左”、“向右”或“不”)；使用催化剂　　　　 反应的△H(填“增大”、“减小”或“不改变”)。

(2)已知：O₂(g) = O₂⁺(g)+e^－　　　　　　 H₁=1175.7 kJ·mol^-1

PtF₆(g)+e^－=PtF₆^－(g)　　　　　　　　　　 H₂=-771.1 kJ·mol^-1

O₂PtF₆(S)=O₂⁺(g)+PtF₆^－(g)　　　　　　　 H₃=482.2 kJ·mol^-1

则反应O₂(g)+PtF₆(g) = O₂⁺PtF₆^－(s)的H=_____________ kJ·mol^-1。

(3)在25℃下，向浓度均为0.1 mol·L^-1的MgCl₂和CuCl₂混合溶液中逐滴加入氨水，先生成　　　　 沉淀(填化学式)，生成该沉淀的离子方程式为　　　　 。已知25℃时K_sp[Mg(OH)₂]=1.8×10^-11，K_sP[Cu(OH)₂]=2.2×10^-20。

(4)在25℃下，将a mol·L^-1的氨水与0.01 mol·L^-1的盐酸等体积混合，反应时溶液中c(NH₄^*)=c(Cl^-)。则溶液显　　　 性(填“酸”、“碱”或“中”)；用含a的代数式表示NH₃·H₂O的电离常数K_b=　　　　　　 。

答案：(1)向左 不改变

(2)－77.6

(3)Cu(OH)₂　 Cu²⁺+2NH₃·H₂O = Cu(OH)₂↓ +2NH₄⁺

　　　　 (4)中　　 　mol·L^-1

解析：(1)恒温、恒压条件下向平恒体系中通入氩气，则反应体系体积增大，平衡左移；使用催化剂只是改变了反应的途径，没有改变反应物与生成物的状态，△H不变；(2)利用盖斯定律，△H₁+△H₂+(-△H₃)= -77.6 kJ·mol^-1；(3)由于,K_sP [Cu(OH)₂]=2.2×10^-20＜K_sp[Mg(OH)₂]=1.8×10^-11，所以先生成沉淀；2NH₃·H₂O+Cu²⁺＝Cu(OH)₂↓+2 NH₄^*；根据溶液的电中性原则，c(NH₄^*)=c(Cl^-)，则[H⁺]＝[OH^-]；溶液显中性；K_b= ，c(NH₄^*)=c(Cl^-)＝0.005 mol·L^-1；[H⁺]＝[OH^-]＝1×10^-7 mol·L^-1(因为是25℃下且为中性)；[NH₃·H₂O]＝mol·L^-1－0.005 mol·L^-1，则：K_b=mol·L^-1。

39．(09年宁夏理综·28)(14分)2SO₂(g)+O₂(g) 2SO₃(g)反应过程的能量变化如图所示。已知1mol SO₂(g)氧化为1mol SO₃的ΔH=-99kJ·mol^-1.请回答下列问题：

(1)图中A、C分别表示　　 、　　 ，E的大小对该反应的反应热有无影响？　 。该反应通常用V₂O₅作催化剂，加V₂O₅会使图中B点升高还是降低？　 ，理由是　　　 ；

(2)图中△H=　 kJ·mol^-1；

(3)V₂O₅的催化循环机理可能为：V₂O₅氧化SO₂时，自身被还原为四价钒化合物；四价钒化合物再被氧气氧化。写出该催化循环机理的化学方程式　　　　　 ；

(4)如果反应速率v(SO₂)为0.05 mol·L^-1·min^-1，则v(O₂)=　　　 mol·L^-1·min^-1、v(SO₃)=　　　 mol·L^-1·min^-1；

(5)已知单质硫的燃烧热为296 KJ·mol^-1，计算由S(s)生成3 molSO₃(g)的△H　　　

　(要求计算过程)。

答案：(1)反应物能量　 生成物能量　 (2)无　 降低　 因为催化剂改变了反应的历程使活化能E降低　 (3)-198　 (4)SO₂ +V₂O₅=SO₃+2VO₂　 4VO₂+ O₂=2V₂O₅　 (4)0.025　 0.05

(5)S(s)+O₂(g) =2SO₂(g)△H₁=-296 KJ·mol^-1 ， SO₂(g)+1/2O₂(g) SO₃(g) △H₂=-99 KJ·mol^-1　

3S(s)+9/2O₂(g)=3SO₃(g) △H=3(△H₁+△H₂)=-1185 KJ·mol^-1　

解析：(1)本小题考查反应物总能量高于生成物总能量为放热反应，可得到A和C所表示的意义，E为活化能与反应热无关，但是用催化剂可以降低活化能；(2)图中表示的是2molSO₂的反应，因此△H=-99×2KJ·mol^-1；(3)依题意即可写出：SO₂ +V₂O₅=SO₃+2VO₂　 4VO₂+ O₂=2V₂O₅；(4)依据速率之比等于化学计量数之比

38．(09年江苏化学·20)(10分)联氨(N₂H₄)及其衍生物是一类重要的火箭燃料。N₂H₄与N₂O₄反应能放出大量的热。

(1)已知：2NO₂(g)===N₂O₄(g)　 △H=-57.20kJ·mol^-1。一定温度下，在密闭容器中反应2NO₂(g)N₂O₄(g)达到平衡。其他条件不变时，下列措施能提高NO₂转化率的是　　 (填字母)。

A．减小NO₂的浓度　　　　　　　　　　　　　　　　 B．降低温度

C．增加NO₂的浓度　　　　　　　　　　　　　　　　 D．升高温度

(2)25℃时，1.00gN₂H₄(l)与足量N₂O₄(l)完全反应生成N₂(g)和H₂O(l)，放出19.14kJ的热量。则反应2N₂H₄(l)+N₂O₄(l)=3N₂(g)+4H₂O(l)的△H=　　　 kJ·mol^-1。

(3)17℃、1.01×10⁵Pa，密闭容器中N₂O₄和NO₂的混合气体达到平衡时，c(NO₂)=0.0300 mol·L^-1、c(N₂O₄)=0.0120 mol·L^-1。计算反应2NO₂(g)N₂O₄(g)的平衡常数K。

(4)现用一定量的Cu与足量的浓HNO₃反应，制得1.00L已达到平衡的N₂H₄和NO₂的混合气体(17℃、1.01×10⁵Pa)，理论上至少需消耗Cu多少克？

答案：(1)BC

(2)-1224.96

(3)根据题意知平衡时：c(N₂O₄)=0.0120 mol·L^-1、c(NO₂)=0.0300 mol·L^-1

K==13.3L·mol^-1

答：平衡常数为13.3。

(4)由(3)可知，在17℃、1.01×10⁵Pa达到平衡时，1.00L混合气体中：

n(N₂O₄)=　c(N₂O₄)×V=0.0120 mol·L^-1×1.00L=0.0120mol

n(NO₂)=　c(NO₂)×V=0.0300 mol·L^-1×1.00L=0.0300mol

则 n (NO₂) 总= n(NO₂)+2n(N₂O₄)=0.0540mol

由Cu+4HNO₃=Cu(NO₃)₂+2NO↑+2H₂O可得

答：理论上至少需消耗Cu 1.73 g.

解析：(1)考查影响化学平衡移动的因素(2)简单的反应热计算要注意将质量转化为物质的量，还要注意比例关系。(3)(4)见答案

[考点分析]^{本题考察了平衡移动原理、反应热计算、平衡常数。高考中的热点和难点。}

37．(09年广东化学·20)(10分)

　甲酸甲酯水解反应方程式为：

HCOOCH₃(l)+H₂O(l)HCOOH(l)+CH₃OH(l)；△H>0

某小组通过试验研究该反应(反应过程中体积变化忽略不计)。反应体系中各组分的起始量如下表：

甲酸甲酯转化率在温度T₁下随反应时间(t)的变化如下图：

(1)根据上述条件，计算不同时间范围内甲酸甲酯的平均反应速率，结果见下表：

请计算15-20min范围内甲酸甲酯的减少量为　　　　　 mol，甲酸甲酯的平均反应速率为 　　　mol·min^-1(不要求写出计算过程)。

(2)依据以上数据，写出该反应的反应速率在不同阶段的变化规律及其原因：　　　　 　。

(3)上述反应的平衡常数表达式为：，则该反应在温度T₁下的K值为 　　　　　　　。

(4)其他条件不变，仅改变温度为T₂(T₂大于T₁)，在答题卡框图中画出温度T₂下甲酸甲酯转化率随反应时间变化的预期结果示意图。

答案：(1)15-20min范围内甲酸甲酯的减少量为0.045mol；甲酸甲酯的平均反应速率为0.009mol·min^-1(2)反应速率随着反应的进行，先逐渐增大再逐渐减小，后不变；原因：随着反应的不断进行，应开始甲酸甲酯的浓度大，所以反应速率较大，后随着反应进行，甲酸甲酯的物质的量浓度不断减少，反应速率不断减慢，所以转化率增大的程度逐渐减小，当反应达到平衡后，转化率不变。

(3)1/7

(4)图略。作图要点：因为T₂>T₁，温度越高，平衡向逆反应方向移动，甲酸甲酯的转化率下降，T₂达到平衡时的平台要低于T₁；另外温度越高，越快达到平衡，所以T₂达到平衡的时间要小于T₁。

解析：(1)15min时，甲酸甲酯的转化率为6.7%，所以15min时，甲酸甲酯的物质的量为1-1.00mol×6.7%==0.933mol；20min时，甲酸甲酯的转化率为11.2%所以20min时，甲酸甲酯的物质的量为1-1.00mol×11.2%==0.888mol，所以15至20min甲酸甲酯的减少量为0.933mol-0.888mol=0.045mol，则甲酸甲酯的平均速率==0.045mol/5min==0.009mol·min^-1。

(2)从题给数据不难看出，平均速率的变化随转化率的增大先增大再减小，后保持不变。因为反应开始甲酸甲酯的浓度大，所以反应速率较大，后随着反应进行甲酸甲酯的浓度减小，反应速率减小，当达到平衡时，反应速率几乎不变。

(3)由图象与表格可知，在75min时达到平衡，甲酸甲酯的转化率为24%，所以甲酸甲酯转化的物质的量为1.00×24%==0.24mol，结合方程式可计算得平衡时，甲酸甲酯物质的量==0.76mol，水的物质的量1.75mol，甲酸的物质的量==0.25mol 甲醇的物质的量==0.76mol

。所以K=(0.76×0.25)/(1.75×0.76)=1/7。

(4)因为升高温度，反应速率增大，达到平衡所需时间减少，所以绘图时要注意T₂达到平衡的时间要小于T₁，又该反应是吸热反应，升高温度平衡向逆反应方向移动，甲酸甲酯的转化率减小，所以绘图时要注意T₂达到平衡时的平台要低于T₁。