问题 选择题

常温下,将200 mL pH = a的CuSO4和K2SO4的混合溶液用石墨电极电解一段时间后,测得溶液的PH变为b(溶液体积的变化忽略不计),在整个电解过程中始终只有一个电极上有气体产生。下列说法错误的是

A.b<a<7

B.阴极电极反应式为:Cu2++2e-="Cu"

C.向溶液中加人9.8x(10-b-10-a)gCu(OH)2可使溶液恢复到电解前的浓度

D.阳极产生的气体是O2,其体积(标准状况下)为1.12x(10-b-10-a)L

答案

答案:C

题目分析:依题意可知整个电解过程中始终发现只有一个电极有气体产生,则整个过程中是阳极产生氧气,阴极析出铜单质,要恢复电解前的溶液就要将氧气和铜的质量转化成CuO或CuCO3,需要20(10-b-10-a)g CuO。考虑水解a<7,电解转变成酸则b<a<7,根据pH的变化可知转移的电子数为(10-b-10-a)mol/L×0.2L,所以产生氧气的体积为。因此C项错误,其余选项均正确。答案选C。

点评: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。

阅读理解

阅读理解。

                                                What makes a house a home?

     Not size, of course. I've been in some of the grandest houses in America, and it's readily apparent no

one lives there. Earlier this year, I had dinner in a mud hut in Ethiopia, where we sat on chairs next to the

hostess' bed -a home that had more warmth than any house I've been in since.

     Now John Edwards is exploring what makes a house a home in his just-released Home: The

Blueprints of Our Lives. There Edwards writes, " This is a book about homes, the values they rest on,

the dreams they are filled with, and the people they have shaped. The houses and circumstances are

different, but much of what you find inside will be familiar."      

     Whether you're sitting in an airport right now, waiting to fly to your childhood home for Thanksgiving,

or in your own home waiting for the relatives to arrive, you know what he's talking about.

     We've lived in our townhouse for 21 years. The loose windows that make noise in the wind. The

fireplace so shallow it holds only one log. The kitchen window that offers a view of the world passing by.

It's where friends sit on the kitchen counter drinking wine while dinner is being fixed.I lived there for only

18, but it will always be my true home. Even the lamp in the west living room window, which I could see

far down the road when driving home late at night, still shines.

     While all this talk about childhood memories can be warm and comforting, home is whom you're with,

not where you are. As Edwards writes, "Home is family. Home is safety. Home is faith."

Happy homecoming.

1.What would be the best title for the text?  

A. Home Means Everything      

B. What's Inside Makes Us Feel at Home

C. Home: The Blueprints of Our Lives    

D. The Importance of the Home

2.The purpose of the second paragraph is to __

A. mean the author likes living in grandest houses

B. prove the author got along well with the hostess

C. mean the feeling of home isn't related to the size

D. show the author's different feelings about houses

3. About the book Home: The Blueprints of Our Lives, we know that __

A. it was the description of Edwards' houses

B. it is mainly about houses

C. it helps us understand the concept of home

D. it was written by the author of the text

4.What did the author mainly mean when he mentioned the loose windows and the shallow fireplace ?

A. His house was too old to live in.

B. He missed the feelings of home.

C. He hated living there.

D. He missed his old friends too much.

5.It can be inferred according to the text that __

A. the author's family were very rich   

B. every happy home is the same

C. the author has been living a hard life  

D. the author and Edwards hold similar ideas

单项选择题 A1型题