问题 填空题

实验室制备硝基苯的主要步骤如下:

①配制一定比例的浓硫酸和浓硝酸的混合酸加入反应器中。

②向室温下的混合酸中逐滴加入一定量的苯,充分振荡,混合均匀。

③在50℃~60℃下发生反应。

④除去混合酸后,粗产品依次用蒸馏水和5%的NaOH溶液洗涤,最后用蒸馏水洗涤。

⑤将用无水氯化钙于燥后的粗硝基苯进行蒸馏,得到纯硝基苯。

(1)配制一定比例浓硝酸和浓硫酸混合酸时,操作注意事项是                                    

(2)步骤③的加热方式是                                    

(3)步骤④中,洗涤、分离粗硝基苯应使用的仪器是                             

(4)步骤④中,粗产品用5%的NaOH溶液洗涤的目的是                                            

(5)现有三种实验装置,如下图所示,要制备硝基苯,应选用 (    )

答案

(1)一定要将浓H2SO4沿内壁缓缓注入盛有浓HNO3的烧杯中,并不断搅拌,冷却

(2)50℃~60℃水浴加热

(3)分液漏斗

(4)洗去粗产品中的酸性杂质

(5)C

   (1)硝基苯的制备中,加入药品必须将浓硫酸加入浓硝酸中,这相当于是浓硫酸的稀释;(2)水浴加热有助于控制温度,且受热均匀;(3)两种不相溶的液体可用分液的方法;(4)粗产品用NaOH溶液洗涤主要是为了洗去溶于溴苯中的Br2

阅读理解

Good morning, class!

We know that there are too many net bars around us. The Internet is popular and it makes our lives colorful. Many of us like going online very much because we can learn how to use the computer and get more information from the Internet. We can learn English. We can read some good newspapers and magazines. It can make us clever in playing computer games. We can send E-mails to our friends quickly. We can chat(聊天) freely online with our friends. It can help us get in touch with people from all over the world.

But some students spend too much time in playing computer game and some stay in the net bars all day and all night. Teenagers even get to have boyfriends or girlfriends online. They write too many letters to each other. It takes them too much time to chat online so they do worse and worse in their lessons and they don’t study well any more. I think we mustn’t get online when it is time for us to study. We can do it in summer or winter holidays. We should get online with adults(成人)--our teacher or parents.

At the same time, if we have lots of free time, we can do some out-of-class activities at school. We usually have activities from 4:50 to 5:50 in the afternoon. We have different kinds of activities. If you are interested in sports, you can play basketball or football. We can go to the English Corner. We can practice talking in English there. We hope we can spend more time on our subjects or on such activities that we can learn a lot from and less time on the Internet.

Thank you for listening to me. That’s all.

小题1:The short passage is about __________.

A.going online

B.how to communicate with others

C.how to spend our free time

D.different kinds of activities小题2:The Internet can make our lives _________.

A.helpful and important

B.enjoyable and interesting

C.enjoyable but expensive

D.different kinds of activities小题3:________ is not good.

A.Sending E-mails

B.Reading newspapers and magazines online

C.going online with adults

D.Spending all day in the net bars小题4:Playing computer games________.

A.gives us lots of information

B.makes our studies worse

C.makes us more clever

D.is harmful to our health小题5:Which of the following is NOT right?

A.There are too many net bars in the cities.

B.We can learn English from the Internet.

C.We mustn’t get online when we are studying at school.

D.We cannot do out-of-class activities from 4:50 to 5:50 p.m.

单项选择题