问题 填空题

(12分)中学常见反应的化学方程式是A+B→X+Y+H2O(未配平,反应条件略去),其中A、B的物质的量之比为1:4。请回答:

(1)若Y是黄绿色气体,则Y的电子式是 _______ ,该反应的化学方程式是__________________________________ 。

(2)若A为非金属单质,构成它的原子核外最外层电子数是次外层电子数的2倍,B的溶液为某浓酸,则反应中氧化剂与还原剂的物质的量之比是____________________。

(3)若A为金属单质,常温下A在B的浓溶液中“钝化”,且A可溶于X溶液中。

①A元素在周期表中的位置是_______(填所在周期和族);Y的化学式是_______。

②含a mol X的溶液溶解了一定量A后,若溶液中两种金属阳离子的物质的量恰好相等,则被还原的X是_______ mol。

答案

(共12分)

(1)(2分)      MnO2+4HCl(浓) MnCl2+Cl2↑+2H2O(2分)    

(2)4:1(2分)  

(3)①第4周期 Ⅷ族(2分)  NO(2分)  ②0.4a(2分)

(1)很明显Y为氯气,与浓盐酸反应的方程式为:

MnO2+4HCl(浓) MnCl2+Cl2↑+2H2O(2分)

(2)A为碳单质;C+4HNO34NO2+CO2+2H2O

(3)A为金属单质,由“钝化”“两种金属阳离子”可判定A为铁。

设被还原的铁离子的物质量为xmol

2Fe3++Fe=3Fe2+

x          1.5x

1.5x=a-x,   x=0.4a

问答题

(46)"Popular art" has a number of meanings, impossible to define with any precision, which range from folklore to junk, with poles being clear enough but the middle tending to blur. The Hollywood Western of the 1930’s, for example, has elements of folklore, but is closer to junk than to high art or folk art. There can be great trash, just as there is bad high art. The musicals of George Gershwin are great popular art, never aspiring to high art. Schubert and Brahms, however, used elements of popular music--folk themes--in works clearly intended as high art. The case of Verdi is a different one : he took a popular genre-- bourgeois melodrama set to music (an accurate definition of nineteenth-century opera)- and, without altering its fundamental nature, transmuted it into high art. (47) This remains one of the greatest achievements in music, and one that cannot be fully appreciated without recognizing the essential trashiness of the genre.

As an example of such a transmutation, consider what Verdi made of the typical political elements of nineteenth-century opera. (48) Generally in the plots of these operas, a hero or heroine--usually portrayed only as an individual, unrestrained by class--is caught between the immoral corruption of the aristocracy and the doctrinaire rigidity of the leaders of the civilians. Verdi transforms this naive and unlike formulation with music of extraordinary energy and rhythmic vitality, music more subtle than it seems at first hearing. There are scenes and arias that still sound like calls to arms and were clearly understood as such when they were first performed. Such pieces lend an immediacy to the otherwise veiled political message of these operas and call up feelings beyond those of the opera itself.

Or consider Verdi’ s treatment of character. (49) Before Verdi, there were rarely any characters at all in musical drama, only a series of situations which allowed the singers to express a series of emotional state. Any attempt to find coherent psychological portrayal in these operas is misplaced ingenuity. The only coherence was the singer’ s vocal technique: when the cast changed, new arias were almost always substituted, generally adapted from other operas. Verdi’ s characters, on the other hand, have genuine consistency and integrity, even if, in many cases, the consistency is that of pasteboard melodrama. The integrity of the character is achieved through the music: (50) once he had become established, Verdi did not rewrite his music for different singers or allow alterations or substitutions of somebody else’s arias in one of his operas, as every eighteenth-century composer had done. When he revised an opera, it was only for dramatic economy and effectiveness.

48()

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