问题 实验题

某化学课外小组用如图所示装置制取溴苯。先向分液漏斗中加入苯和液溴,再将混合液慢慢滴入反应器A(A下端活塞关闭)中。

(1)写出A中反应的化学方程式________________。

(2)观察到A中的现象是____________________________________。

(3)实验结束时,打开A下端的活塞,让反应液流入B中,充分振荡,目的是________________,写出有关的化学方程式___________________。

(4)C中盛放CCl4的作用是____________________。

(5)若证明苯和液溴发生的是取代反应,而不是加成反应,可向试管D中加入AgNO3溶液,若产生淡黄色沉淀,则能证明。另一种验证的方法是向试管D中加入__   _,现象是_______________________ 。

答案

(10分)(1)

(2)反应液微沸,有红棕色气体充满A容器   (3)除去溶于溴苯中的溴

Br2+2NaOH=NaBr+NaBrO+H2O 或    3Br2+6NaOH=5NaBr+NaBrO3+3H2O

(4)除去溴化氢气体中的溴蒸气    (5)石蕊试液 溶液变红色(其他合理答案都对)

题目分析:(1)装置A中用来制备溴苯的,所以A中反应的化学方程式是

(2)由于该反应是放热反应,且单质溴易挥发,所以实验中观察到的实验现象是反应液微沸,有红棕色气体充满A容器。

(3)由于生成的溴苯中含有溶解的单质溴,所以让反应液流入氢氧化钠溶液中的目的是除去溶于溴苯中的溴,有关反应的方程式是Br2+2NaOH=NaBr+NaBrO+H2O,或3Br2+6NaOH=5NaBr+NaBrO3+3H2O。

(4)由于单质溴易挥发,会干扰溴化氢的检验,所以四氯化碳的作用是除去溴化氢气体中的溴蒸气。(5)由于溴化氢溶于水溶液显酸性,据此可以检验,即向试管D中加入石蕊试液,而实验现象是溶液变红色。

点评:该题是高考中的常见题型,属于中等难度的试题。试题贴近高考,针对性强,主要是考查学生对溴苯制备原理、物质的除杂、物质的检验的了解掌握情况,有助于培养学生规范严谨的实验设计能力,有利于提高学生的应试能力,有助于提升学生的学科素养。

阅读理解

That warm day was the only day of the week without rain.I opened the door,took a seat and began to enjoy the wonderful sunshine.Suddenly,I noticed that the house near mine had been sold.An elderly lady was in front of the door,with some beautiful flowers beside her.I walked to her.She looked to be in her early eighties and had the prettiest white hair.

“Hi!My name is Karmen,”I said smiling brightly at the old lady.She smiled back and said,“Hello,Karmen.I ’m Henrietta.”Her voice was very strong for someone at her age.Later,I learned she was alone and had no family or relatives to help her.From that day on,I often visited her and helped her with her housework and sometimes she gave me some delicious food.A year passed,and I considered Henrietta to be one of my best friends.

One day,I walked over for my morning visit and knocked on the door,but there was no answer.I knocked again,and she still didn’t turn up.So I let myself in,using the key she had given me.I checked her living room and then her kitchen.I finally went into her bedroom,and she was lying peacefully on her bed.Beside her there were two notes.One was her will(遗嘱),which said all that she had would be given to me.The other was a thank-you note.I went to her bedside and cried sadly.

Though several years have gone by,I still miss her deeply.Whenever I look at the beautiful flowers in front of her house,I remember the wonderful friendship we had.

小题1:The writer came out of the house to ______.

A.look at an old lady

B.enjoy some flowers

C.enjoy the sunshine

D.clean the house nearby小题2:Through visiting the old lady,the writer learnt that the old lady ______.

A.disliked all her relatives

B.had no one to look after her

C.didn’t want to live with her family

D.was looking for someone to look after her小题3:What can we learn from the passage?

A.The old lady was not kind.

B.The writer didn’t have any good friends.

C.The old lady didn’t know how to make food.

D.The writer got along very well with the old lady.小题4:What does the underlined part “turn up”in Paragraph 3 mean?

A.Appear

B.Leave

C.Try

D.Change

判断题