问题 实验题

(1)控制变量是科学研究中的重要研究方法,其基本思路是,在实验研究中人为只改变一个因素(调节变量),其他因素保持相同,观察测定因调节变量改变而改变的因素(因变量),从而分析得到研究结论.中学化学中应用控制变量的方法研究问题的例子很多.请分析或设计:

①在研究浓度对化学反应速率的影响时,教材安排了利用Na2S2O3与H2SO4反应的一组对照实验(Na2S2O3+H2SO4 Na2SO4+S↓+SO2↑+H2O) 为0.20 mol/L, c(OH-)的起始浓度为1.50 mol/L,则反应速率v=____________.

在三个烧杯(底部有黑色“十”字标记)内分别加入表中所示体积的三种液体,搅拌并开始计时,到出现浑浊使烧杯底部“十”字看不见时停止计时.比较所需时间,得出浓度对化学反应速率影响的结论.实验中,温度和反应体系中硫酸浓度是保持相同的因素,调节变量是________,因变量是________.

②运用控制变量原理设计实验,利用纯碱溶液探究温度对盐的水解的影响,简述实验方法:___________________________________________________.

(2)373 K时,H2PO3与OH发生如下反应: H2PO3+OH HPO32-+H2O 反应结果如下表所示:  

如果用v=kcm(H2PO3)·cn(OH)表示反应速率(k为与浓度无关的常数)

①k=________, m=________, n=________.

②若c(H2PO4)的起始浓度为0.20 mol/L, c(OH)的起始浓度为1.50 mol/L,则反应速率v=____________.

答案

(1)①Na2S2O3溶液的浓度 ;所需时间

②取三支试管各放同浓度同体积的纯碱溶液,滴1~2滴酚酞试液,第一支不加热,第二支加热至t1℃,第三支加热至t2℃,观察三支试管中溶液的颜色深浅,温度越高,颜色越深,说明碱性越强,则水解程度越大(其他合理答案均给分,例如不同温度下测定同浓度同体积纯碱溶液的pH)

(2)①3.2×10-4 ;1 ;2

②1.44×10-4mol/(L·s)

阅读理解

Several years ago, a television reporter was talking to three of the most important people in America. One was a very rich banker, another owned one of the largest companies in the world, and the third owned many buildings in the center of New York.

The reporter was talking to them about being important. “How do we know if someone is really important?” the reporter asked the banker. The banker thought for a few moments and then said,” I think anybody who is invited to the Whiter House to meet the President of the United States is really important. ”

The reporter then turned to the owner of the very large company. “Do you agree with that?” she asked. The man shook his head, “No. I think the President invites a lot of people to the White House. You’d only be important if while you were visiting the President, there was a telephone call from the president of another country, and the President of the US said he was too busy to answer it. ”

The reporter turned to the third man. “Do you think so?” “No, I don’t.” he said. “I don’t think that makes the visitor important. That makes the President important. ” “Then what would make the visitor important?” the reporter and the other two men asked.

“Oh, I think if the visitor to the White House was talking to the President and the phone rang, and the President picked up the receiver, listened and then said, “It’s for you.”

小题1:There are _______ in this passage.

A.two men and two women

B.three men and one woman

C.three women and one man

D.four women小题2:The banker thought _______.

A.he was really important because he was a rich banker

B.the visitor to the White House was really important

C.the visitor who met the President of the United States

D.the reporter was really important小题3: The owner of many buildings thought _______.

A.he was really important because he owned many buildings in the center of New York

B.the owner of the very large company was really important

C.the visitor was really important if he was talking to the President and the President received a telephone call for the visitor

D.the person who worked in the White House was really important

选择题