问题 问答题

为了测定水的组成选用下列装置回答问题:(氢气用盐酸和锌制得)

(1)为准确测定水的组成,为防止杂质干扰,正确的连接顺序为:己→______→丙;

(2)乙装置的作用是______.

(3)若测得丁装置中样品在实验前后减少6.4克,乙装置中药品增加了7.2克,丙装置增加了3.6克,根据此可求出水中H、O质量比为(只写计算式)______.

(4)实验结束后,若丁处仍有黑色固体,这对实验的结果的影响是______(填“氧的质量偏大”、“氢的质量偏大”、“无影响”);

(5)装置中的丙能否省去?______为什么?______.

答案

(1)为准确测定水的组成,防止杂质干扰,从己中生成的氢气带有氯化氢气体和水蒸气,依次通过甲和戊除去,然后再通过丁还原氧化铜,反应后生成的水蒸气经过乙被吸收,最后再连接丙装置,丙的作用是吸收空气中的水蒸气,以免进入乙装置影响测定结果.可用于干燥的装置除丙外还有乙和戊,由于装置戊不便于称量变化前后的质量,所以不应位于丁装置后吸收反应生成的水.综上所述,可得出装置的连接顺序:己→甲→戊→丁→乙→丙.

(2)装置乙中放入大量的干燥剂,直接和丁装置相连,所以其作用应是吸收丁装置反应产生的水;

(3)丁中金属氧化物反应前后减少的质量为6.4克,即水中氧元素的质量;乙装置增加的质量7.2克即为生成水的质量;7.2克-6.4克为氢元素的质量.根据此可求出水中H、O质量比为(7.2-6.4):6.4;

(4)实验结束后,丁处仍有黑色固体说明CuO没有全部参加反应,不参加反应的CuO在反应后仍在装置内,不影响反应前后的称重.另外,本次探究的是生成水中H、O元素的质量关系,CuO是否全部反应只是影响生成水的多少,不影响质量比的推算;

(5)装置丙也用于吸收水和二氧化碳,因为丙处于装置乙之后的整套装置的最末端直接与大气相通,所以该装置一定不是用于吸收反应中生成的水,那么就是用来吸收空气中的水和二氧化碳.这样可以减少空气中水和二氧化碳对探究结果的影响,保证实验结果的准确性.

故答案为:

(1)甲→戊→丁→乙;

(2)吸收氢气还原氧化铜后生成的水;

(3)(7.2g-6.4g):6.4g;

(4)无影响;

(5)不能;它的目的是吸收空气中的水蒸气和二氧化碳,否则会影响实验的结果.

完形填空
Maybe you are an average student. You probably think you will never be a top student. This is not necessary so, however. Anyone can become a better student if he or she wants to. Here is how.  
1). Plan your time carefully. When you plan your week, you should make a list of things that you can have to do. After making the list, you should make a schedule of your time. First time for eating, sleeping, dressing, etc. Then decide a good, regular time for studying. Don’t forget to set aside enough time fro entertainment. A weekly schedule may not solve all your problems, but it will force you to realize what is happening to your time.  
2). Find a good place to study. Look around the house for a good study area. Keep this space, which may be a desk or simply a corner of your room. Free from everything but study materials. No games, radios, or television. When you sit down to study, concentrate on the subject.   
3). Make good use of your time in class. Take advantage of class time to listen to everything the teachers say. Really listening in class means less work later. Taking notes will help you remember what your teachers say.  
4). Study regularly. When you get home from school, go over your notes. Review the important points that your teachers mentioned in class. If you want to know what your teacher is going to discuss the next day, read the material in advance. This will help you understand the next class. If you do these things regularly, the material will become more meaningful, and you will remember it longer.  
5). Develop a good attitude about tests. The purpose of a test is to show what you have learned about a subject. They help you remember your new knowledge. The world won’t end if you don’t pass a test, so don’t be overly worried. 
There are other methods that might help you with your studying. You will probably discover many others after you have tried these.  
How to Become A Better Student?
General methods  
How to  
Advantages  
plan you time carefully  
●    make a list  
●    make a 小题1:  
force you to realize 小题2: is happening to your time  
find a good place to study  
free of everything but study     小题3:
you can 小题4: on the subjects  
make good use of your time in class  
●listen to everything the teachers say  
●take 小题5:
really listening in class means   小题6:work later.  
study regularly  
●    go over your notes  
●    小题7:new materials   
Help you 小题8:it better, remember it longer   
develop a good attitude about tests  
don’t be 小题9:worried   
remember your new 小题10:
单项选择题 A1型题