问题 问答题

下列A~F是初中化学中的六个实验,请按要求填空:

(1)D实验中烧杯③的作用是______,F实验中搅拌的目的是______.

(2)B实验中红磷燃烧的化学方程式为______,实验说明氧气的体积约占空气的______,实验成功的关键是______(填序号).

①装置气密性好;②实验前夹紧止水夹;③红磷过量或足量;④冷却后再打开止水夹;⑤要选用教室内的空气.

(3)E实验的全过程观察到的现象是______;发生反应化学方程式为______.

(4)上述实验中能达到实验目的且正确的是______(填字母).

答案

(1)同样是酚酞溶液,在不同的环境中,很明显烧杯③的作用就是作为对比实验,玻璃棒的作用有很多种,在这里考虑到浓硫酸溶于水要放出大量的热,所以玻璃棒的作用就是使溶解过程中的热量散失或者是使受热均匀,故本题答案为:作对比或对比实验;散热(使产生的热量迅速扩散)或混匀

(2)要保证本实验成功,装置的密封性要好,不能产生装置内外的温度差,所以本题答案为:4P+5O2

 点燃 
.
 
2P2O5;1/5;①②③④

(3)从本装置可以看出,若二氧化碳与氢氧化钠发生了反应,那么装置中的压强就会减小,从而气球会膨胀,由于反应要生成碳酸钠,那么滴入盐酸后就会生成二氧化碳,由于二氧化碳的生成就会使装置中的压强变大,从而压缩气球变小,所以本题的答案为:①滴入氢氧化钠溶液后,气球膨胀,②滴入盐酸后,产生气泡,③气球缩小

   CO2+2NaOH═Na2CO3+H2O       Na2CO3+2HCl═2NaCl+H2O+CO2

(4)A中二氧化碳的密度比空气大,故应该用向上排空气法收集,C中验证的是燃烧的条件,但是有所给装置我们可以看出仅仅是比较了空气中的白磷和水中的白磷,也就说仅仅验证了在同是可燃物这两种环境下能否燃烧,也就是验证了两个条件,对于着火点这一条件没有比较,F中的操作也是错误的,正确的操作:把浓硫酸缓慢的加入到水中,并不断搅拌,防止液滴的迸溅所以能够达到目的是:B、D、E

完形填空
完形填空。
      Sato Miyoko is a Japanese schoolgirl. She didn't have a camera.    1   she lives out in the country,
there is no place    2   a very good camera. She decided to buy a digital camera online    3   it could be
sent to her.
      She had searched the Internet for two hours    4    she found an ad for the Sony digital camera. She
liked the    5  . After she had found more information, she asked her father if she    6    buy it. Mr. Sato
looked at the ad. Then he found ads for other cameras     7  . After he had checked out all the information
about different kinds of cameras, he believed his daughter had    8    a good decision. This camera seemed
to offer the most at the    9   price. He helped her order the camera online.
      Miyoko clicked   10   the screen, and a form. appeared for her to fill in her personal information. Her
dad helped her   11   the form. and typed in his credit card number. Miyoko filled in their   12  , address
and e-mail address. Then a screen came up that read, "Congratulations! You have   13   bought a Sony
camera." A week later Miyoko received the camera she had   14  .
      Miyoko came to Beijing with her friends last month. She enjoyed her visit to Beijing so much that
she    15   with the new camera. They will help her remember this special trip forever.
( )1. A. For    
( )2. A. buy    
( )3. A. so      
( )4. A. when    
( )5. A. ad      
( )6. A. will    
( )7. A. as well 
( )8. A. got    
( )9. A. good    
( )10. A. in      
( )11. A. fill in 
( )12. A. telephone
( )13. A. never   
( )14. A. seen    
( )15. A. has a good time    
             C. takes a lot of photos
B. As             
B. find           
B. that         
B. then           
B. picture       
B. can           
B. by the way     
B. made           
B. better         
B. on             
B. fill         
B. names         
B. successfully   
B. made       
  

C. Because of 
C. to buy    
C. so that    
C. while    
C. information 
C. must      
C. in the end 
C. found      
C. best      
C. with      
C. write      
C. ages      
C. success    
C. ordered    
B. had a good time      
D. took a lot of photos 

D. As if            
D. to find          
D. while              
D. after         
D. size and shape   
D. could            
D. at last          
D. did              
D. most             
D. at               
D. copy             
D. telephone number
D. yet              
D. bought      


     
选择题