问题 填空题

(10武汉30).(5分)根据下列的实验装置图回答问题。

(1)装置Ⅰ在实验中可用于过氧化氢溶液制氧气,其反应的化学方程式为        

(2)在化学实验中,对装置稍加改装或采用不同的组合时,就能完成多种实验。如将装置Ⅱ改为Ⅳ后,可以顺利进行草酸受热扫解的实验。

草酸是一种有机物,常温时为一种无色透明的晶体,加热时易分解。草酸受热分解的化学方程式为:C2H2O2==H2O+CO2+CO

根据改进后图Ⅳ所示实验装置推测草酸还具有的物理性质为                

(3)现将装置Ⅳ与装置Ⅲ相连,对草酸受热分解后所得产物的组成和性质进行探究。实验开始前E中左右液面在同一水平面上。

①装置Ⅲ中A可用于收集反应生成的水,还具有      的作用;

②实验过程中,D中一直无明显现象,E中球容器内液面         (填“升高”、“降低”或“不变”)。

答案

(1)2H2O2====2H2O+O2

(2)熔点较低

(3)①安全瓶  ②降低

(1)过氧化氢在二氧化锰作催化剂的条件下分解生成水和氧气,反应的化学方程式为:2H2O22H2O+O2↑;

(2)将装置Ⅱ改为Ⅳ,区别就是将酒精喷灯改为酒精灯,因为酒精灯火焰的温度比酒精喷灯的低,说明草酸的熔点较低;

(3)①二氧化碳和氢氧化钠溶液反应后压强减小,为了防止倒吸,所以A装置即可以收集反应生成的水还具有安全瓶的作用;②随着一氧化碳的不断生成,会使得E中压强增大,所以E中球容器内液面降低.

故答案为:(1)2H2O22H2O+O2↑;(2)熔点较低;(3)①安全瓶;②降低.

阅读理解

阅读理解。

     Tom was from Canada and he had come to New York for a holiday. One day he was not feeling well,

so he asked a man of his hotel to find a doctor. The man said, "Thomas Brown is a good doctor." Tom said,

"Thank you very much. Is he expensive?" "Well" the man answered, "he always asks his patients (病人) for

two dollars if they are first visit. One dollar if they are later visit." Tom decided to save one dollar, so when

he went to see the doctor, he said, "I've come again, doctor." For a few minutes the doctor looked at his

face carefully without saying anything. Then he said, "Everything's going as it should do. Oh, I gave you

medicine last time, didn't I? Just go on with it."

1. Tom came to New York ______.

A. to see a good doctor

B. for a holiday

C. to feel ill

D. to find a doctor

2. Doctor Thomas Brown asked for ______ for the first time.

A. one dollar

B. two dollars

C. nothing

D. three dollars

3. The doctor looked at Tom's face carefully because ______.

A. he knew Tom

B. he had seen Tom before

C. there was something wrong with his face

D. he wanted to know if Tom had been here before

4. Tom said,"I've come again, doctor." Because he ______.

 A.wanted to be friendly to the doctor

B.wanted to make the doctor happy

C.wanted to make the doctor angry

D.tried to make the doctor believe that he had been to him before

5. The doctor knew that ______.

A. Tom didn't want any medicine

B. he hadn't seen Tom before

C. he had given Tom some medicine before

D. Tom wasn't feeling ill

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