(9分)酸碱中和滴定是中学化学常见实验。 某同学欲测定某浓硫酸样品的物质的量浓度

题型:实验题

问题:

(9分)酸碱中和滴定是中学化学常见实验。

某同学欲测定某浓硫酸样品的物质的量浓度,进行了以下实验操作:

A.冷却至室温后,在100mL容量瓶中定容配成100mL稀硫酸。

B.量取20.00mL稀硫酸于锥形瓶中并滴入几滴指示剂。

C.将酸式滴定管和碱式滴定管用蒸馏水洗涤干净,并用各待盛溶液润洗。

D.将物质的量浓度为1.50mol/L标准NaOH溶液装入碱式滴定管,调节液面记下读数V1。E.继续滴定至终点,记下读数为V2

F.在锥形瓶下垫一张白纸,把锥形瓶移到碱式滴定管下小心滴入NaOH标准溶液,边滴边摇动锥形瓶。

G.量取浓硫酸样品5mL,在烧杯中用蒸馏水溶解。

H.重复以上实验。

请回答下列问题:

(1)该实验正确操作步骤的顺序为:

  → A→    →D→    → H

(用编号字母填写)。

(2)量取5mL浓硫酸的仪器是     ;量取20.00mL稀硫酸的仪器是      

(3)选用的指示剂是       。滴定过程中,视线应注视          ;判断到达滴定终点的现象是                   

(4)下表是实验测得的有关数据:

滴定序号待测稀硫酸的体积(mL)所消耗NaOH标准溶液液的体积(mL)
V1V2
20.000.5022.60
20.006.0027.90
请计算出该浓硫酸样品的浓度为      mol·L1(不必写出计算过程)。

考点:燃烧热水的离子积常数水电离的影响因素水的电离平衡
题型:实验题
完形填空。
     There are many kinds of friends. Some are always   1    you, but don't understand you. Some
say only a few words to you, but understand you. Many people will step in your life, but only   2  
 friends leave footprints (脚印).
     I shall always recall (回忆) the autumn and the girl with the   3   . She will always bring back the
friendship between us. I know she will always be my best friend. It was the golden season. I could
see the yellow leaves   4   on the cool    5  . In such a season, I liked walking alone in the leaves,
    6   to the sound of them.
     Autumn is a    7   season and life is uninteresting. The free days always get me   8   . But one day,
the sound of a violin    9   into my ears like a stream (小溪) flowing in the mountains. I was so
surprised that I jumped to see what it was. A young girl, standing in the wind, was    10   in playing
her violin.
     I had   11   seen her before. The music was so nice that I listened quietly. Lost in the music, I didn't
know that I had been   12    there for so long but my existence (存在) did not seem to disturb her.
     Leaves were still falling. Every day she played the violin in the corner of the building    13   I went
downstairs to watch her performance. I was the only listener. The autumn seemed no longer lonely and
life became    14    .    15   we didn't know each other, I thought we were already good friends. I
believe she also loved me.
     Autumn was nearly over. One day, when I was listening carefully, the sound suddenly   16    . To
my astonishment (惊讶), the girl came over to me.
    "You must like violin." she said.
     "Yes. And you play very well. Why did you stop?" I asked.
     Suddenly, a   17   expression appeared on her face and I could feel something unusual. "I came
here to see my grandmother, but now I must leave. I once played very badly. It was your listening
every day that   18   me." she said.
     "In fact, it was your playing    19   gave me a meaningful autumn," I answered, "Let's be friends."
     The girl smiled, and so did I.
     I never heard her play again in my life. I no longer went downstairs to listen like before. Only thick
leaves were left behind. But I will always remember the fine figure (身影) of the girl. She is like a   20 
-so short, so bright, like a shooting star giving off so much light that it makes the autumn beautiful.
( ) 1. A. with      
( ) 2. A. good      
( ) 3. A. sound      
( ) 4. A. shaking    
( ) 5. A. wind      
( ) 6. A. watching  
( ) 7. A. lively    
( ) 8. A. up        
( ) 9. A. flowed    
( )10. A. lost      
( )11. A. once      
( )12. A. waiting    
( )13. A. because    
( )14. A. interesting
( )15. A. But        
( )16. A. stopped    
( )17. A. happy      
( )18. A. surprised  
( )19. A. that      
( )20. A. song      
B. for        
B. true      
B. song      
B. hanging    
B. snow      
B. listening  
B. lovely    
B. off        
B. grew      
B. active    
B. never      
B. stopping  
B. so        
B. moving    
B. However    
B. began      
B. sad        
B. excited    
B. which      
B. dream                
C. against    
C. new        
C. play        
C. falling    
C. air        
C. seeing      
C. harvest    
C. down        
C. entered    
C. busy        
C. often      
C. standing    
C. when        
C. encouraging
C. Even        
C. gone        
C. strange    
C. encouraged  
C. it          
C. fire        
D. to          
D. old          
D. violin      
D. floating    
D. rain        
D. hearing      
D. lonely      
D. over        
D. ran          
D. interested  
D. usually      
D. hearing      
D. but          
D. exciting    
D. Though      
D. changed      
D. surprised    
D. interested  
D. who          
D. sister      
题型:实验题

=______。

题型:实验题

化纤其他童游戏套装紧身及套头衫

题型:实验题

某集团总公司为其子公司与某钢厂的钢材买卖合同在1000万元的限度内提供连带保证,并委派专人监督合同的执行。钢厂交付给子公司的价值50万元的一批钢材质量严重不合格,子公司未提出异议并接受了货物,但集团总公司以书面形式向钢厂提出了异议,要求退货。子公司与钢厂的买卖总价款额达到800万元时,集团总公司以书面通知钢厂终止保证合同,但在钢厂收到该通知之前钢厂又交付给子公司价款额为100万元的钢材,钢厂收到通知后又交付给子公司价款额为100万元的钢材。集团总公司承担保证责任的范围应当是()

A.1000万元

B.900万元 

C.850万元

D.750万元

题型:实验题

按照网络所使用的传输技术将网络分成两类: 【3】 网络和点对点网络。

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