问题 填空题

氯水具有多种性质,根据新制氯水分别与如图五种物质发生的反应填空(氯水足量):

(1)a、b、c中反应的离子方程式为:                                                         

e中的化学反应方程式为                       。上述反应中发生了氧化还原反应的是:       (填“a”、“b”、“c”或“e”)。

(2)能证明氯水具有漂白性的现象是____________________________。

(3)久置的氯水变为________,用化学反应方程式表示为__________。

(4)实验室保存饱和氯水的方法是_____________________________。

答案

(1)2Fe2++Cl2===2Fe3++2Cl-(1分)

2H++CO32-===H2O+CO2↑(1分)

Ag++Cl-===AgCl↓(1分)

2Cl2+2Ca(OH)2===Ca(ClO)2+CaCl2+2H2O ,(2分)

ae(1分)

(2)氯水与石蕊试液反应,先变红后褪色(1分)

(3)稀盐酸(1分) 2HClO2HCl+O2↑(1分)

(4)在阴凉处置于棕色试剂瓶中密封保存(1分)

题目分析:(1)a为Cl2氧化Fe2+,离子方程式:Cl2+2Fe2+=2Cl‾+2Fe3+,b为氯水中的盐酸与Na2CO3,离子方程式为:CO32‾+2H+= H2O+CO2↑,c为氯水中的Cl‾与AgNO3溶液中的Ag+反应,离子方程式为:Cl‾+Ag+===AgCl↓,e为Cl2与Ca(OH)2反应,离子方程式为:2Cl2+2Ca(OH)2===Ca(ClO)2+CaCl2+2H2O ,ae中反应元素化合价发生了变化,为氧化还原反应。

(2)把新制氯水加入石蕊试液,氯水显酸性使石蕊变红,HClO使石蕊褪色,说明氯水具有漂白性。

(3)HClO分解生成HCl和O2,所以久置的氯水变为稀盐酸,化学方程式为:2HClO2HCl+O2

(4)因为HClO在光照条件下易分解,所以氯水在阴凉处置于棕色试剂瓶中密封保存。

完形填空

(三)完形填空(共 10 小题;每小题 1 分,满分 10 分)阅读下面短文,掌握其大意,然后从30 至第40 小题所给的A、B、C、D 四个选项中,选出最佳选项,并在答题卡上将该项涂黑。

I feel it enjoyable and exciting to study in a British high school for one year. Life there was quiet different from what I 31 in China. The average size for British schools is much 32 and there were only 29 students in our class. We had to move to different classrooms for different classes. We also had different students in some classes, 33 it difficult to remember all the faces and names. I found the homework was less heavy than 34 in my old school, but all the homework was in English. That is 35 it was a bit challenging for me at first. 36, all my teachers were very helpful and I enjoyed all my subjects. My English 37 a lot as I used English every day and 38 an hour each day reading English books in the library. Students at that school are required to study Math, English and Science, but they can choose other subjects 39. I 40 to have Chinese food a lot at lunchtime there and I missed my parents very much. I usually went to the Computer Club at lunchtime, so I could e-mail my family and friends back home for free.

31. A. used to       B. was similar to   C. was used to        D. was familiar to

32. A. less         B. smaller        C. fewer            D. bigger

33. A. making       B. causing       C. resulting            D. leading

34. A. it            B. one          C. which              D. that

35. A. when         B. why          C. where            D. because

36. A. Unfortunately  B. Eventually     C. Luckily            D. Hopefully

37. A. improved      B. raised         C. rose              D. lifted

38. A. took           B. paid          C. cost              D. spent

39. A. in themselves   B. of themselves    C. by themselves     D. to themselves

40. A. looked forward  B. intended        C. wished for        D. did want

单项选择题