问题 实验题

已知Fe(NO3)2受热分解产物为金属氧化物、NO2和O2,请完成表格内容并回答相关问题:

(1)对固体产物中Fe化合价的猜想:

猜想一:只显+2价 猜想二:只显+3价;猜想三:               

(2)为证明猜想二通过完成下表加以验证。供选试剂有: 0.01 mol/L 酸性KMnO4溶液、0.1 mol/L H2SO4溶液、3%H2O2溶液、0.1 mol/LKSCN溶液、蒸馏水。(仪器自添)

实验操作现象目的或结论
步骤1:取适量上述热分解后的固体于试管中,加入0.1 mol/L H2SO4溶液使其充分溶解,将上层清液分加到A、B两支试管中 溶解固体产物
步骤2: 溶液中含有Fe3+
步骤3: 溶液中不含 Fe2+
 

经验证,猜想二正确,请写出Fe(NO3)2热分解的化学方程式                        

(3)某同学将带火星的木条伸入该分解反应产生的气体中,木条复燃,由此他得出“NO2能支持燃烧的结论”。请你判断该结论是否正确?并说明理由。

答案

⑴既有+2价又有+3价(2分)不写“+”号或写成“2+”、“3+”、“Fe2+”、“Fe3+”等,不给分。

实验操作现象
步骤2:向A试管中滴入几滴0.1mol/LKSCN溶液溶液呈血红色
步骤3:向B试管中滴入几滴0.01mol/L酸性KMnO4溶液酸性KMnO4溶液不褪色
 

每空2分。

操作部分:所用试剂须从“供选试剂”中选用,否则不给分。“KSCN”、“KMnO4”化学式写错,不给分。若操作部分错误,则现象部分答案不论对错均不给分。

现象部分:“血红色”可写为“红色”,写成“砖红色”、“红褐色”、“血红色沉淀”等,不给分。“褪”字写错扣1分。

4Fe(NO3)22Fe2O3+8NO2↑+O2↑(2分)化学式错,不得分;配平及条件错,扣1分。

⑶结论正确。(1分)

Fe(NO3)2分解后的气体产物中,NO2和O2的体积比为8:1,O2的体积分数小于空气中氧气的体积分数21%,若NO2不支持燃烧,则木条不会复燃。(2分)

能说明该反应产生的气体中氧气浓度较低,若NO2不支持燃烧,则木条不会复燃即可。

题目分析:从铁的硝酸盐分解,用氧化还原角度来看,N(+5→+2),O(-2→0),故铁的化合价可能变也可能不变,故为+2或+3价,然后据此进行探究。根据+2和+3价铁离子的检验设计实验方案,得出相关的结论。对于NO2能否支持燃烧的结论,要从,O2的百分含量的角度定量进行考虑。

完形填空

第二节完形填空(共20小题;每小题1分,满分20分)

请认真阅读下面短文,从短文后各题所给的A、B、C、D四个选项中,选出最佳选项。

A young school teacher had a dream that an angel appeared to him and said, “You will be given a child who will grow up to become a world   36 . How will you prepare her so that she will realize her intelligence, grow in confidence, develop both her confidence and sensitivity, be open-minded, yet   37  in character? In short, what kind of education will you   38  so that she can become one of the world's truly great leaders?”

The young teacher    39  in a cold sweat. It had never occurred to him before ---any one of his present or future students could be the person   40 in his dream. Was he preparing them to rise to any position which they may   41 ? He thought, “How might my   42  change if I knew that one of my students were this person?” He   43 began to formulate (规划;想出)a plan in his mind.

This student would   44  experience as well as instruction. She would need to know how to solve problems of various kinds. She would need to know the value of lifelong learning in order to keep a curious and   45  mind.

His teaching  46 . Every young person who walked through his   47 became, for him, a future world leader. He saw each one, not   48  they were, but as they could be. He   49  the best from his students, yet tempered(使缓和)it with pity. He taught each one as if the future of the       50  depended on his instruction.

After many years, a woman he knew   51  to a position of world fame. He realized that she must   52  have been the girl described in his dream. Only she was not one of his   53 , but rather his daughter. For of all the   54  teachers in her life, her father was the best.

Where and how you will   55  this child is a mystery. But believe that one child's future may depend upon the influence only you can provide, and something remarkable will happen.

36. A. leader                  B. destroyer                   C. rescuer                D.protector

37. A. bad                     B. weak                        C. special                 D. strong

38. A. afford                  B. provide                     C. receive                D. have 

39. A. awaken                 B. feared                       C. awoke                 D. stood

40. A. described       B. appeared                    C. imagined               D. lived 

41. A. buy                     B. send                        C. make                  D. desire

42. A. performance           B. teaching                     C. acting                  D. learning 

43. A. gradually              B. gladly                       C. suddenly               D. finally  

44. A. like                    B. have                        C. need             D. mean

45. A. actual                   B. dependent               C. absent            D. active 

46. A. worked                 B. changed                    C. developed              D. finished

47. A. classroom               B. office                       C. house                  D. mind

48. A. like                    B. unlike               C. likely                 D. as

49. A. begged                  B. expected                    C. forced                 D. learned 

50. A. world                   B. school                      C. class                   D. family 

51. A. appeared                B. stood                       C. rose                    D. raised 

52. A. completely              B. nearly                      C. hardly                  D. surely

53. A. children                 B. students                    C. friends                 D.followers

54. A. male                    B. wise                 C. various                 D. language

55. A. raise                    C. help                        C. love                    D. meet

单项选择题 A1型题