问题 问答题

(1)已知Na2S2O3+H2SO4=Na2SO4+S↓+SO2+H2O.甲同学通过测定该反应发生时溶液变浑浊的时间,研究外界条件对化学反应速率的影响.设计实验如下(所取溶液体积均为10mL):

实验编号实验温度/℃c(Na2S2O3)/mol•L-1c(H2SO4)/mol•L-1
250.10.1
250.10.2
500.20.1
500.10.1
其他条件不变时:探究浓度对化学反应速率的影响,应选择______(填实验编号);

探究温度对化学反应速率的影响,应选择______(填实验编号).

(2)已知Na2S2O3溶液与Cl2反应时,1mol Na2S2O3转移8mol电子.该反应的离子方程式是______.

甲同学设计如下实验流程探究Na2S2O3的化学性质.

(Ⅰ)甲同学设计实验流程的目的是证明Na2S2O3溶液具有碱性和______性.

(Ⅱ)生成白色沉淀B的离子方程式是______.

(Ⅲ)乙同学认为应将上述流程中②③所加试剂顺序颠倒,你认为甲、乙两同学的设计更合理的是______(填“甲”或“乙”),理由是______.

答案

(1)实验①、②的温度相等,c(Na2S2O3)相等,但c(H2SO4)不等,故实验①、②是探究浓度对化学反应速率的影响.实验①、④中c(H2SO4)和c(Na2S2O3)均相等,但温度不等,故实验①、④是探究温度对化学反应速率的影响,故答案为:①②;①④;

(2)氯气有强氧化性,能将S2O32-氧化为2SO42-,故反应的离子方程式是:S2O32-+4Cl2+5H2O=2SO42-+8Cl-+10H+,故答案为:S2O32-+4Cl2+5H2O=2SO42-+8Cl-+10H+

(Ⅰ)甲同学的实验流程中通过加入BaCl2 产生白色沉淀B 来证明Na2S2O3 与氯水反应时有SO42-生成,即证明S2O32-具有还原性,故答案为:还原; 

(Ⅱ)硫酸根可与钡离子反应生成硫酸钡沉淀,离子方程式是:SO42-+Ba2+=BaSO4↓,故答案为:SO42-+Ba2+=BaSO4↓;

(Ⅲ)在证明Na2S2O3的还原性时由于不知道BaS2O3 是否是沉淀,所以应先加BaCl2 溶液,如果不产生白色沉淀再加足量氯水产生白色沉淀,即可证明Na2S2O3具有还原性,故乙可排除BaS2O3的干扰,故答案为:乙;可以排除BaS2O3的干扰.

多项选择题
阅读理解

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项. 选项中有两项为多余选项. 请将答案涂在答题卡上.

 71  Because, from what I could see, it seemed that grown-ups often forgot. I never wanted to forget --- I wanted to be able to remind other adults and myself when the time came. I began consciously(有意识地) thinking this at quite an early age.

As soon as I was fully aware (意识到) of myself, I regarded me as a little person and liked adults who thought of and treated me the same way. I didn’t have a doll and I didn’t want one. I wanted animal toys, even a single animal. Why wouldn’t my parents give me the one thing I wanted?  72  

Instead, my dad somehow managed to buy me a full set of encyclopedia(百科全书) and books with maps and color pictures long before I could read. Well, guess what? I learned to read without realizing it! Later, I found out when I started school and it all came so easy especially geography.  73  Because of all the books my father bought me, I knew a lot of words that other children didn’t know at my age.

I love words. They opened up new worlds for me.  74  Parents, please make sure your kids have a computer. Let them explore — as safely as possible— let them do their own things and discover the world.

Now, most kids lead a happy life. They can get what they want from their parents. But children should learn to be independent.  75  Be independent to do your own things.

A.Because of them, I read and thought, and today, I write.

B.When I was a child, I promised myself to try to remember as much as I could.

C.I listened and heard everything, even if I didn’t understand everything.

D.I nearly knew every place on the map like the teacher.E. But more than anything, it made me feel uncomfortable and I knew it wasn’t nice.

F. Later, I knew we didn’t have much money, but how expensive could a toy be?

G. Be independent to learn some useful knowledge.