问题 选择题

常温下,下列溶液的pH或微粒的物质的量浓度关系正确的是

A.将0.2mol/L的某一元酸HA溶液和0.1mol/L NaOH溶液等体积混合后溶液pH大于7,则反应后的混合液:2c(OH)=2c(H+)+c(HA)-c(A)

B.某溶液中存在的离子有S2—、HS、OH、Na+、H+,则离子浓度的大小关系一定是:c(Na+)>c(S2—)>c(OH)>c(HS)>c(H+)

C.pH=3的二元弱酸H2R溶液与pH=11的NaOH溶液混合后,混合液的pH等于7,则反应后的混合液:c(R2—)+c(HR)=c(Na+)

D.某物质的溶液中由水电离出c(H+)=1×10—amol/L,若a>7时,则该溶液的pH一定为14-a

答案

答案:A

题目分析:A.将0.2mol/L的某一元酸HA溶液和0.1mol/L NaOH溶液等体积混合后得到的溶液为HA与NaA按照1:1的混合溶液。由于混合溶液的pH大于7,则说明A-的水解作用大于HA的电离作用。根据电荷守恒可得:c(H+)+ c(Na+)= c(OH)+ c(A)。根据物料守恒可得:c(HA)+c(A)=2c(Na+)。两式联立求解可得:2c(OH)=2c(H+)+c(HA)-c(A)。正确。B.某溶液中存在的离子有S2—、HS、OH、Na+、H+,若为Na2S溶液,则离子浓度的大小关系一定是:c(Na+)>c(S2—)>c(OH)>c(HS)>c(H+)。若为NaHS溶液,则离子浓度的大小关系一定是:c(Na+) >c(HS) >c(OH)>c(S2—) > c(H+)。错误。C.pH=3的二元弱酸H2R溶液与pH=11的NaOH溶液混合后,混合液的pH等于7,根据物料守恒可得则反应后的混合液:2c(R2—)+c(HR)=c(Na+)。错误。D.某物质的溶液中由水电离出c(H+)=1×10—amol/L,若a>7时,则水的电离受到了抑制,该溶液可能呈酸性,也可能呈碱性。若为酸性该溶液的pH为14-a;若为碱性,则pH=a.错误。

阅读理解

One evening in February 2007, a student named Paula Ceely brought her car to a stop on a remote road in Wales. She got out to open a metal gate that blocked her path .That’s when she heard the whistle sounded by the driver of a train. Her Renault Clio was parked across a railway line. Seconds later, she watched the train drag her car almost a kilometre down the railway tracks.

Ceely’s near miss made the news because she blamed it on her GPS (导航仪). She had never driven the route before. It was dark and raining heavily. Ceely was relying on her GPS, but it made no mention of the crossing. “I put my complete trust in the device and it led me right into the path of a speeding train,” she told the BBC.

Who is to blame here? Rick Stevenson, who tells Ceely’s story in his book When Machines Fail Us, points the finger at the limitations of technology. We put our faith in digital devices, he says, but our digital helpers are too often not up to the job. They are filled with small problems. And it’s not just GPS devices: Stevenson takes us on a tour of digital disasters involving everything from mobile phones to wireless keyboards.

The problem with his argument in the book is that it’s not clear why he only focuses on digital technology, while there may be a number of other possible causes. A map-maker might have left the crossing off a paper map. Maybe we should blame Ceely for not paying attention. Perhaps the railway authorities are at fault for poor singalling system. Or maybe someone has studied the relative dangers and worked out that there really is something specific wrong with the GPS equipment. But Stevenson doesn’t say.

It’s a problem that runs through the book. In a section on cars, Stevenson gives an account of the advanced techniques that criminals use to defeat computer-based locking systems for cars. He offers two independent sets of figures on car theft; both show a small rise in some parts of the country. He says that once again not all new locks have proved reliable. Perhaps, but maybe it’s also due to the shortage of policemen on the streets. Or changing social circumstances. Or some combination of these factors.

The game between humans and their smart devices is amusing and complex. It is shaped by economics and psychology and the cultures we live in. Somewhere in the mix of those forces there may be a way for a wiser use of technology.

If there is such a way, it should involve more than just an awareness of the shortcomings of our machines. After all, we have lived with them for thousands of years. They have probably been fooling us for just as long.

小题1:What did Paula Ceely think was the cause of her accident?

A.She was not familiar with the road.

B.It was dark and raining heavily then.

C.The railway workers failed to give the signal.

D.Her GPS device didn’t tell her about the crossing.小题2:The phrase “near miss” (Paragraph 2) can best be replaced by______.

A.close hit

B.heavy loss

C.narrow escape

D.big mistake小题3:Which of the following would Rick Stevenson most probably agree with?

A.Modern technology is what we can’t live without.

B.Digital technology often falls short of our expectation.

C.Digital devices are more reliable than they used to be.

D.GPS error is not the only cause for Ceely’s accident.小题4:In the writer’s opinion, Stevenson’s argument is _______.

A.one-sided

B.reasonable

C.puzzling

D.well-based小题5:What is the real concern of the writer of this article?

A.The major causes of traffic accidents and car thefts.

B.The relationship between human and technology.

C.The shortcomings of digital devices we use.

D.The human unawareness of technical problems.

填空题