问题 填空题

在实验室里制取乙烯时,常因温度过高而发生副反应,部分乙醇跟浓H2SO4反应生成SO2,CO2,水蒸气和炭黑.

(1)用编号为①→④的实验装置设计一个实验,以验证上述反应混合气体中含CO2,SO2和水蒸气.用装置的连接顺序(按产物气流从左到右的流向):______→______→______→______.

(2)实验的装置①中A瓶的现象是______;结论为______.B瓶中的现象是______;B瓶溶液作用为______.若C瓶中品红溶液不褪色,可得到结论为______.

(3)装置 ③中加的固体药品是______以验证混合气体中有______.装置  ②中盛的溶液是______以验证混合气体中有______.

答案

(1)检验二氧化硫用品红溶液,检验二氧化碳用澄清的石灰水,检验水蒸气用无水硫酸铜,因溶液中有水,所以先检验水蒸气,然后检验二氧化硫,同在检验二氧化碳之前用溴除尽SO2,再通过品红溶液不褪色确认SO2已除干净,

故答案为:④③①②;

(2)实验的装置①中A瓶装的是品红溶液,当混合气体通过A瓶时,品红褪色,说明产物中有二氧化硫;溴水能和二氧化硫反应,所以,二氧化硫能被溴水吸收,当混合气体再次通过品红时,不褪色说明品红已全部被吸收,

故答案为:品红褪色;混合气体中有二氧化硫;溴水褪色;将二氧化硫吸收完全;混合气体已无二氧化硫;

(3)装置③的作用为检验水蒸气的存在,白色无水硫酸铜变成蓝色晶体,说明有水蒸气存在,装置②的作用为检验二氧化碳的存在,当澄清石灰水变浑浊,说明有二氧化碳存在,

故答案为:无水硫酸铜;水蒸气;澄清石灰水;CO2

单项选择题
阅读理解

阅读理解。

     Recently, in the hope of earning both money and social experience, I became a door-to-door salesman. I once read a saying: "If somebody wants something of you, you will be treated as warmly as spring, but if they don't you may be treated as coldly as winter." You may consider it an exaggeration(夸张),but if you are a salesman, it is clearly correct.

     You would never have found it to be so true if you hadn't been a salesman. You needn't stand doubtful looks and unfriendly views; you needn't listen to something completely wrong and nod to say that it was quite right; you needn't always keep patience and smile; you needn't repeat the same sentences over again; you needn't talk to somebody you dislike.

     I did this work for a month; then I decided to give it up. In spite of the above reasons, I found I was paying too much attention to the job and thus sacrificing my study time. The latest test result proved that my grades were getting lower. Even worse, I hadn't enough time to join my classmates in college activities. Sometimes I felt lonely and unhappy because of both my study and my part-time job. Now I don't think it is worth doing such a thing even though I was earning money at great cost.

     Newspapers and magazines often publish stories about good students who do part-time work and keep high scores in class. But according to my experience, part-time work can have some strong bad effects on study.

     Most students don't see the relationship between studies and work in a correct way. In my opinion, if it isn't a must for money reasons, students should be cautious about taking up a part-time job. In western countries even the children of very rich families take part in hard jobs during the summer vacation.

1. What caused the writer to give up his part-time job?

A. Too much attention to it and his grades getting lower

B. He often missed some college activities

C. Sometimes he felt tired and unhappy

D. All the above

2. Which of the following has the closest meaning to the underlined word "sacrificing"?

A. losing

B. wasting

C. using

D. getting

3. The writer thought __________.

A. to do part-time job was unnecessary

B. part-time jobs had good effect upon study

C. it's hard to plan study and work correctly

D. part-time jobs were good for students

4. Who should take part-time jobs according to the text above?

A. Every college student

B. Those who want to get study experience

C. Those in great need of money

D. Those from very rich families