问题 填空题

(10重庆綦江23)我们学习了实验室制取O2和CO2的方法,相信你能够回答下列间题。

(1)实验室翻取O2可以选捧多种药品,当选择高锰酸钾时,发生反应的化学方程式为:

__________________________________。

如果要收集纯度比较高的O2,最好用_________法收集。比较用过氧化氢溶液和用氯酸钾制取O2的方法,二者的共同点是____________。

A.发生装置相同

B.都可用MnO2作催化剂

C.反应的基本类型相同

D.完全反应后剩余固体成分相同(2)李丽同学设计了实验室制取CO2装置(如下图所示),装置中出现了一个错误,你的纠正方法是_____________________。

锥形瓶中发生反应的化学方程式为_____________________________________

铜丝上下抽动起到的作用是_________________________。

如果将铜丝网改成铁丝网,收集到的CO2中还会含有_________。

答案

(1)2KMnO4 K2 MnO4 + MnO2  + O2 ↑       排水     BC

(2)用向上排空气法收集CO2

CaCO 3+ 2HCl ="==" CaCl2  + H2 O + CO2↑。

使反应随时停止和发生         H2

分析:(1)可比较两种制取氧气的反应原理进行对比,根据氧气的水溶性结合实验目的选择收集方法.

(2)根据二氧化碳是密度来判断收集方法的正误;根据反应的操作性分析铜丝的作用;根据铁的化学性质及反应液进行分析铁丝的反应.

解答:解:(1)实验室用高锰酸钾制取氧气的反应方程式为:2KMnO4 K2 MnO4 + MnO2  + O2

用双氧水制取氧气的反应方程式为:2H2O22H2O+O2↑,因为氧气不溶于水,密度比空气大,可用排水法和向下排空气法收集,根据实验目的要求收集比较纯净的氧气,所以用排水法;对比两种方法可知因为条件不同所以反应装置不同,二氧化锰第一个和第二个都是催化剂,反应类型都是分解反应,生成物不相同,所以选C.

故答案为:2KMnO4 K2 MnO4 + MnO2  + O2 ↑;排水法; B

(2)大理石和稀盐酸反应的化学方程式为:CaCO3+2HCl=CaCl2+H2O+CO2↑,因为二氧化碳密度大于空气,所以应该用向上排空气法收集;操作时当铜丝向上提升时,大理石和盐酸分离,反应停止,落下时接触反应开始,所以铜丝的作用是使反应随时停止和发生;当把铜丝换成铁丝时,铁丝可用和盐酸反应生成氢气.

故答案为:用向上排空气法收集CO2; CaCO3+2HCl=CaCl2+H2O+CO2↑;使反应随时停止和发生;H2

阅读理解

阅读理解。    

       When Martin was a little boy, he lived in the little town-Holtham. At that time he thought the town

was very big.    

       Well, Martin came back to the town last night. "It's a small town," he thought.  The town has

changed very little in the past forty years, but Martin has changed a great deal. He has grown into a

man. His thoughts are a man's. He sees things through a man's eyes.    

       Martin stayed in the town for five hours. He walked from street to street, but he knew nobody.

Was Holtham, then a town of strangers? No, he suddenly understood it all. Only he was a stranger in

the town.

1. Martin left the town           .      

A. when he was forty      

B. forty years ago      

C. when he was fourteen      

D. five hours ago  

2. In the past years, Martin has changed                    

A. his face      

B. his clothes      

C. a little        

D. a lot    

3. Martin thought the town was a small town because         ,   

A. he saw things through a stranger's eyes      

B. he had been away from the town for too long      

C. he saw things through a man's eyes now      

D. he didn't like the town any longer   

4. Martin           during his five-hour stay in the own.      

A. met no friends      

B. didn't want to see his friends      

C. saw nobody      

D. saw a lot of friends

5. Which of the following is TRUE?      

A. Martin was not a stranger in the town.      

B. Holtham was a town of strangers to Martin.      

C. Great changes have taken place in the town.  

D. A man's thoughts are better than a child's thoughts.

单项选择题 B1型题