问题 实验题

(10分)(1)为了检验和除去下表中的各种杂质(括号里的为杂质),请从①中选出适当的检验试剂,从②中选出适当的除杂试剂,将所选的答案用字母填入相应的空格内。

物质检验试剂除杂试剂
甲烷(乙烯)  
酒精(水)  
①检验的试剂:

A.无水硫酸铜  B.酸性高锰酸钾溶液  C.水  D.氢氧化钠溶液

②除杂试剂:

a.无水硫酸铜  b.乙酸    c.新制的生石灰  d.溴水

③写出除杂时,乙烯发生反应的化学方程式:

___________________________________________________________________

(2)如图,在左试管中先加入2 mL 95%的乙醇,并在摇动下缓缓加入3 mL浓硫酸,再加入2 mL乙酸,充分摇匀。按图连接好装置,用酒精灯对左试管小火加热3~5 min后,改用大火加热,当观察到右试管中有明显现象时停止实验。

试回答:

在右试管中通常加入________溶液,实验生成的乙酸乙酯,其密度比水________,是有特殊香味的液体。分离右试管中所得乙酸乙酯的操作为(只填名称)________。反应中加入浓硫酸的作用是________。

答案

(1)

物质检验试剂除杂试剂
甲烷(乙烯)Bd
酒精(水)Ac
 

(2)饱和Na2CO3 小 分液 催化剂、吸水剂

(1)①乙烯含有碳碳双键,能和溴水发生加成反应,也能和酸性高锰酸钾溶液发生氧化反应而褪色,所以二者都可以鉴别甲烷和乙烯;由于酸性高锰酸钾溶液能把乙烯氧化生成CO2,所以要除去甲烷中的乙烯,应该用溴水。

②要检验酒精中的水,一般用无水硫酸铜;但要除去水,则需要加入生石灰,然后蒸馏即可。

③乙烯和溴水发生加成反应的方程式为CH2=CH2+Br2CH2BrCH2Br。

(2)由于生成的乙酸乙酯中含有乙酸和乙醇,而乙酸乙酯不溶于水,所以要分离提纯乙酸乙酯,应该加入饱和碳酸钠溶液。乙酸乙酯的密度小于水的,由于不溶于水,分液即可;由于酯化反应是可逆反应,所以在反应中,浓硫酸除了起催化剂的作用外,还起吸水剂的作用。

阅读理解

阅读下面课文段落,按照句子结构的语法性和上下文的连贯要求,空格处各填入一个适当的单词,使短文通顺完整。请将答案写在二卷答题纸上。

◣ A ◢

(Book 4 Unit 2  Working the land)

Although he is one of China’s most famous scientists, Yuan Longping considers himself a farmer, for he works the land to do his research. Indeed, his sunburnt face and   小题1: and his slim, strong body are just like those of millions of Chinese farmers, for whom he has   小题2:  for the past five decades. Dr Yuan Longping grows what is called super hybrid rice.   小题3:  1974, he became the first agricultural pioneer in the world to grow rice that has a high   小题4:. This special strain of rice makes it possible to produce one-third more of the   小题5:  in the same fields. Now more than 60% of the rice produced in China each year is from this hybrid strain.

◣ B ◢

(Book 4 Unit 5  Theme parks)

The theme park you are probably most familiar with is Disneyland. It can be found in several   小题6:  of the world. It will bring you into a magical world and make your dreams come   小题7: , whether traveling through space, visiting a pirate ship or meeting your favourite fairy tale or Disney cartoon character. As you   小题8: around the fantasy amusement park, you may see Snow White or Mickey Mouse in a parade or on the street. Of course Disneyland also has many exciting rides, from giant   小题9: ships to terrifying free-fall drops. With all these attractions, no wonder tourism is increasing wherever there is a Disneyland. If you want to have   小题10: and more than fun, come to Disneyland!

多项选择题