问题 选择题

一定温度下,取pH=12的NaOH溶液和氨水各10 mL,分别用蒸馏水冲稀至1 L。关于稀释后的溶液的pH的说法正确的是(   )

A.NaOH溶液的pH大于氨水的pH

B.NaOH溶液的pH小于氨水的pH

C.两溶液的pH相等

D.无法判别两溶液pH的相对大小

答案

答案:B

氨水稀释后,NH3·H2O+OH-,上述平衡右移,使n(OH-)增大,最终,NaOH溶液中c(OH-)小于氨水中c(OH-)。

单项选择题
问答题

To get help, Internet addicts tired of their square-eyed, keyboard tapping ways need look no further than the Web for counseling. There is now an online counseling service at www. relate, org. nz for Internet obsessives. Just e-mail the details of your Internet-induced crisis and help comes direct to your inbox. (46)The new breed of cybertherapists see nothing strange about offering help through the very medium that is swallowing their clients’ free time and splitting their marriages.

Getting hooked on the Internet isn’t confined to a few computer nerds. It’s on the rise everywhere—and women are the most likely addicts. The old stereotypical addict was a young man who spent hours playing games, downloading software or reading messages on newsgroups. (47)Yet, the new image is of a young woman who fritters away hours e-mailing friends, buying books and CDs online, talking in chatrooms and looking for information for next year’s holiday.

Ingrid Parker, once a slave to Internet chatrooms, found her experiences so devastating that she wrote a book to help other addicts break the habit. (48) Her computer dream turned to nightmare when she sold up and moved to be with her cyberpal (who had just left his wife), only to be told a week later that the couple were getting back together. The heart-breaking turn of events gave her the motivation to control her addiction—and write the book Caught in the Web.

For Ingrid Parker, anyone who is married or in a sound relationship should not really be spending hours talking to someone else and ignoring their nearest and dearest. (49)While Parker provided her own therapy by putting her experiences down on paper, she recommends others take up the online counseling offer, or log off from the Worldwide Web gradually.

She said, "It’s like smoking. It’s not a good idea to suddenly go cold turkey. People often e mail me about the problem and I tell them to gradually wean themselves off and not to switch to a scheme where you pay per hour for online time. (50)If they break their resolution, all they end up with then is the same old problem plus money difficulties for the long hours they have spent logged in to the Internet. "

Of course, the Internet is definitely addictive but if you can keep it in control it has advantages, too. Using it can be a steep learning curve so it helps you become very quick at learning. Also there is a huge demand for people in the field of Information Technology (IT) and hours on the Internet are great training.

(50)If they break their resolution, all they end up with then is the same old problem plus money difficulties for the long hours they have spent logged in to the Internet. "