问题 问答题

在容积为V L的密闭容器中发生2NO2⇌2NO+O2的反应.反应过程中NO2的物质的量随时间变化的状况如图所示.

(1)若曲线A和B表示的是该反应在某不同条件下的反应状况,则该不同条件是______.

A.有、无催化剂    B.压强不同    C.温度不同

(2)写出该反应的化学平衡常数K的表达式______,并比较

K800℃______K850℃(填>、<或=).

(3)求在B条件下从反应开始至达到平衡,氧气的反应速率VO2=______.

(4)能说明该反应已达到平衡状态的是______.

A.V正(NO2)=V逆(NO)

B.C(NO2)=C(NO)

C.气体的平均摩尔质量不变

D.气体的密度保持不变.

答案

(1)由图象可知B状态反应较快,且A、B处于不同平衡状态,肯定不是催化剂的影响,如是压强的影响,则增大压强,平衡向逆反应方向移动,则NO2的物质的量应增大,但B状态NO2的物质的量较少,应是升高温度的原因,该反应的正反应为吸热反应,升高温度平衡向正反应方向移动,则NO2的物质的量减少,故答案为:C;

(2)平衡常数等于生成物的浓度幂之积除以反应物的浓度幂之积,则k=

c2(NO)•c(O2)
c2(NO2)
,反应的正反应为吸热反应,升高温度平衡向正反应方向移动,则平衡常数增大,

故答案为:k=

c2(NO)•c(O2)
c2(NO2)
;<;

(3)根据图象可知,B状态时,平衡时NO2的物质的量为0.1mol,则反应的NO2的物质的量为0.1mol,生成O2的物质的量为0.05mol,则VO2=

0.05mol
VL
2s
=
0.025
V
mol/(L•s),

故答案为:

0.025
V
mol/(L•s);

(4)A.V正(NO2)=V逆(NO),说明正逆反应速率相等,反应达到平衡状态,故A正确;

B.C(NO2)=C(NO),正逆反应速率不相等,没有达到平衡状态,故B错误;

C.气体的质量不变,气体的平均摩尔质量不变,则说明气体的物质的量不变,说明反应达到平衡状态,故C正确;

D.由于气体的质量不变,气体的体积不变,则无论是否达到平衡状态,都存在气体的密度保持不变的特征,不能判断是否达到平衡,故D错误.

故答案为:AC.

填空题
完形填空

完形填空(共20小题,每小题1.5分,满分30分)

I did very badly at school. My headmaster thought I was  36  and when I was 14 he said, “You’re never going to be   37   but a failure.”

After five years of   38  jobs, I fell in love with a very nice middle-class girl. It was the best   39   that could have happened to me. I   40   I wanted to do something positive (积极地) with my life because I wanted to prove to   41   that what people said about me was   42 . Especially her mother, who had said to me, “Let’s   43   it, you’ve failed at everything you’ve ever done.”  So I tried hard with my  44   and went to college. My first novel (小说)  45   while I was at college.

After college I taught during the   46   in high schools and attended evening classes at London University, where I got a    47   in history. I became a lecturer at a college and was thinking of  48   that job to write full time   49   I was offered a part-time job at Leeds University. I began to feel proud of myself —  50   was a working--class boy who’d   51   school early, now teaching at the university.

My writing career (职业) took off when I discovered my own style. Now I’m rich and   52 , have been on TV, and met lots of film stars.   53   what does it mean? I   54   wish all the people that have put me down had  55  : “I believe in you. You’ll succeed.”

36. A. bright                       B. useless                             C. simple                             D. hopeful

37. A. anything                  B. something                      C. everything                    D. nothing

38. A. low                           B. poor                                 C. good                               D. useful

39 A. support                             B. happiness                       C. surprise                         D. thing

40. A. admitted                 B. decided                       C. planned                         D. told

41. A. me                           B. them                                C. her                                   D. it

42. A. wrong                   B. right                               C. stupid                         D. faulty

43. A. see            B. know                     C. understand                D. face

44. A. experiment     B. practice                   C. writing                     D. composition

45. A. came on        B. came in                   C. came out                   D. came back

46. A. day            B. night                      C. month                    D. year

47. A. graduation      B. pass                     C. degree                   D. success

48. A. giving in         B. giving back                    C. giving out                  D. giving up

49. A. while          B. if                                 C. when                      D. or

50. A. there          B. here                                C. it                         D. that

51. A. left            B. attended                 C. changed                  D. graduated

52. A. tired           B. calm                      C. nervous .                  D. famous

53. A. And            B. But                      C. However                  D. Well

54. A. just            B. exactly                  C. so                        D. very

55. A. praised          B. said                      C. answered                  D. advised