问题 选择题

25℃时,Ksp(BaSO4)=1×10-10,Ksp(BaCO3)=2.6×10-9.该温度下,下列说法不正确的是(  )

A.同浓度的Na2SO4和Na2CO3混合溶液中滴加BaCl2溶液,BaSO4先析出

B.BaCO3的悬浊液中加入少量的新制氯水,c(Ba2+)增大

C.BaSO4和BaCO3共存的悬浊液中

c(S
O2-4
)
c(C
O2-3
)
=
1
26

D.BaSO4悬浊液中加入Na2CO3浓溶液,BaSO4不可能转化为BaCO3

答案

A.25℃时,Ksp(BaSO4)=1×10-10,Ksp (BaCO3)=2.6×10-9,物质Ksp小的容易生成沉淀,所以同浓度的Na2SO4和Na2CO3混合溶液中滴加BaCl2溶液,BaSO4先析出,故A正确;

B.BaCO3的悬浊液中存在沉淀溶解平衡,加入氯水,c(CO32-)的浓度减小,沉淀溶解平衡正移,所以c(Ba2+)增大,故B正确;

C.根据Ksp(BaSO4)和Ksp(BaCO3)计算可求出中

c(S
O2-4
)
c(C
O2-3
)
=
Ksp(BaSO4)
Ksp(BaCO3)
=
1
26
,故C正确;

D.当Qc=c(CO32-)•c(Ba2+)≥Ksp(BaCO3),就能转化为BaCO3,所以当c(CO32-)足够大时,能满足Qc=c(CO32-)•c(Ba2+)≥Ksp(BaCO3),所以BaSO4能转化为BaCO3,故D错误;

故选:D.

阅读理解

C

Dear Ariel,

I got a job offer from a high-tech company with a fairly satisfactory payment and benefits.Even the work environment is cool.But I heard that the job requires a lot of overtime and even weekends.I know it’s important for newcomers to get their feet planted firmly on the ground to reach their goals, but I’m scared of the idea of having nearly no free time.I still need to find a girlfriend and look after my parents.So, shall I accept the job or give it up for another one with much less pay and more freedom?

Amoretto

Dear Amoretto,

I have two things to say: First, you’re lucky to have such an excellent offer, especially at a time when so many talented people are struggling to find any work at all; and second, you can’t figure out your work-life balance until you’re actually working.

Take the job.You’ll be learning, doing interesting things, working in a cool environment, and making money.If you’re given contract, make sure you understand the terms before you sign.Ask your boss how many hours a week you’re expected to work.If he tells you a number that’s much lower than what you find once you’re working, you’ll be in a better position to talk to him about it.

Give your work 100 percent.Work energetically and efficiently.If you’re devoted and focused, you might achieve more than your co-workers in less time.Showing yourself to be a productive and talented worker from the beginning will give you more bargaining power.Finally, remember that taking a job doesn’t have to be a life commitment.Try to give it at least a year(two is better).If you’re really miserable after that time, look for another job that will give you more freedom.By then, you’ll have workplace experience, bosses and colleagues who can speak positively about your work and some savings as well.

Good luck!

Ariel

64.When considering the job offer, Amoretto is most concerned about whether he’ll have______.

A.a pay rise     B. a girlfriend       C.free time      D. cool working condition

65.We can infer that Ariel thinks________.

A.young people are faced with a fierce competition in job-hunting

B.a good start and 100% devotion to the work are of great importance

C.Amoretto should ask nothing until he actually works in the company

D.beginning workers with bargaining power are not popular with bosses

66.Ariel recommended Amoretto to_____.

A.balance his life and work before taking the job

B.analyze the contract carefully before signing it

C.spare no effort to please his boss and colleagues

D.be a lifelong worker for the company whatever happens

67.In the first letter, the underlined part “get their feet planted firmly on the ground” means______.

A.present themselves truthfully        B.face the reality bravely

C.be conscious of their abilities        D.work heart and soul

选择题