问题 选择题

用碱性氢氧燃料电池为电源进行电解的实验装置示意图如下所示。下列说法中正确的

是(    )

A.燃料电池工作时,负极反应为:H2 – 2e= 2H+

B.若要实现铁上镀铜,则a极是铁,b极是铜

C.若a极是粗铜,b极是纯铜时,a极逐渐溶解,b极上有铜析出

D.a、b两极均是石墨时,在相同条件下当电池中消耗H2 22.4 L(标准状况)时,a极析出铜64 g

答案

答案:C

题目分析:根据图示可知,左边是原电池,右边是电解池,原电池中H2是负极,电极反应为:H2 -2e-+2OH-= 2H2O,O2是正极,电极反应为:O2+4e+2H2O=4OH-,电解池中a是阳极,b是阴极,要想实现铁上镀铜,铁做阴极,铜做阳极,要想精炼铜,精铜在阴极,粗铜在阳极,如果两个电极都是石墨,则标准状况下电池中消耗H2 22.4 L是,b极析出64g铜。因此A、B、D错误,C是正确,答案选C。

点评:在原电池中较活泼的金属作负极,失去电子,发生氧化反应。电子经导线传递到正极上,所以溶液中的阳离子向正极移动,阴离子向负极移动。正极得到电子,发生还原反应,据此可以进行有关的判断。电解中最关键的是准确判断出电极上离子的放电顺序。在判断电解产物时,首先判断阳极电极材料。如果是活性电极,则电极本身失去电子。如果是惰性电极,则溶液中的阴离子失去电子。而阴极是溶液中的阳离子得到电子,所以需要熟练记住常见离子的放电顺序。

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In the southern part of America, when somebody has a birthday, often family or friends, or both, will arrange a party. The party could be elaborate(精心准备的)and include a meal or may be simple with a birthday cake and drinks. One does not plan, nor give, one’s own birthday as is the custom in some cultures. At a party there is usually a decorated cake, often with the words “Happy Birthday” and with the name of the person written on the top of the cake. Sometimes there is also one candle for each year of the person celebrating the birthday before the cake is cut. While blowing out the candles, the person makes a wish for something pleasant.

Usually those invited to a birthday party will bring a gift for the person honored. Gifts given by friends do not have to be expensive, but the family of the birthday person will spend whatever they can afford on a gift.

Christmas parties also are very popular in the South. Often this is the only time during the year that some people see acquaintances(熟人). These parties can be elaborate or simple, ranging from a buffet(自助餐)to a reception called “open house (家庭招待会)”. If you are invited to one of these, you don’t need to take a Christmas gift, as it is not customary to take the hostess a gift every time you are invited to a party or a meal. However, if you wish to take a gift, it should only be something useful and inexpensive and should be given to the hostess at the door as you enter the party. Usually gifts of Christmas food treats are the most appreciated.

51. On one’s birthday, before blowing out the candles, he or she will______.

A. wear beautiful clothes          B. eat birthday cake

C. invite friends                 D. make a wish

52. This passage mainly tells us about __________.

A. two kinds of parties in the southern United States

B. how to arrange a birthday party

C. how to arrange a Christmas party

D. who will arrange a party

53. In southern America , birthday parties are often arranged by _________.

A. friends     B. oneself      C. family        D. Both A and C

54. Which of the following is true?

A.For a birthday party, the cake is often cut before candles are blown out.

B.For a birthday party, neither friends nor the family will buy expensive presents.

C. It’s customary to take the hostess a gift when you are invited to a party.

D.If you take a gift to a Christmas party, you’d better take something useful and inexpensive.

55. What kind of gift is the best if someone is invited to a Christmas party?

A. Expensive things     B. Candles      C. Food      D. Money