问题 选择题

将镁片和铁片用导线连接置于同一稀盐酸溶液中,经过一段时间后,下列叙述正确的是

A.正极附近Cl-的浓度逐渐增大

B.溶液中Cl-的浓度总体上基本不变

C.负极上有Cl2逸出,正极上有H2逸出

D.溶液的pH在电池工作过程中基本不变

答案

答案:B

专题:电化学专题.

分析:镁片-铁片-稀盐酸溶液构成了原电池,较活泼的金属镁作负极,铁作正极,负极上镁失电子发生氧化反应,正极上氢离子得电子发生还原反应,溶液中阳离子向正极移动阴离子向负极移动,根据溶液中氢离子浓度的变化判断溶液中pH值的变化.

解答:解:A、原电池放电时,较活泼的金属镁作负极,铁作正极,溶液中阴离子向负极镁片移动,导致负极附近氯离子的浓度逐渐增大,故A错误; B、原电池放电时,负极上镁失电子生成镁离子进入溶液,正极上氢离子得电子析出氢气,溶液中氯离子没有参加反应,所以溶液中Cl-的浓度总体上基本不变,故B正确; C、原电池放电时,负极上镁失电子生成镁离子进入溶液,正极上氢离子得电子析出氢气,故C错误;

D、原电池放电时,负极上镁失电子生成镁离子进入溶液,正极上氢离子得电子析出氢气,导致溶液中氢离子浓度降低,溶液的pH值增大,故D错误;故选B。

点评:本题考查了原电池原理,知道正负极上发生的电极反应、溶液中离子的移动方向、溶液中PH值与氢离子浓度的关系即可解答本题,难度不大。

单项选择题 A1型题
阅读理解

阅读表达。

阅读短文,并按照题目要求用英语回答问题。

     In order to be a success in the American business world, you must get along with people. You must

learn to behave yourself in such a way that you earn the affection and respect of others. As we have

already pointed out, Americans mix business and pleasure. Therefore, learning how to chat informally

(非正式地)can be a help with your American business contracts. Americans like to talk about a number

of different topics-sports, politics, cars, popular movies, television shows and personal interests.

     Many large American cities have sports teams. If you are working with Americans in the United

States, it would be a good idea to find out about the local sports teams so that you can join in the almost

inevitable discussions about "What our team will do this year." Politics can be a sensitive topic unless

everyone is of the same mind politically. Limit your discussions to asking questions of your friends. Most

Americans are car owners and some are even obsessive(着迷的)about the subject. You can contribute

to the discussion by talking about cars you have owned or by sharing information you have had in

automotive magazines. Americans watch television almost every night and attend movies regularly, so

naturally TV programs and the latest movies become topics for discussions.

     If you are unable to watch American television or attend American movies, reading the entertainment

section of such magazines as Time and Newsweek will keep you up to date on what is popular in

America.

1. What's the best title of the passage? (No more than 10 words)

   ________________________________________________________________________

2. Why should people be careful with the topic-politics? (No more than 8 words)

   ________________________________________________________________________

3. If you want to keep you up to date on what is popular in America, what should you do?  (No more

    than 10 words)

   ________________________________________________________________________

4. The underlined word "affection" in Paragraph 1 refers to ________.(No more than 4 words)

5. Suppose you are doing business in America, what would you do to be a success in business world?

    (No more than 20 words)

   ________________________________________________________________________

   ________________________________________________________________________