问题 填空题

向草酸(H2C2O4)溶液中逐滴加入酸性高锰酸钾溶液时,溶液褪色总是先慢后快。对其原因,某研究性学习小组结合化学反应原理提出猜想与假设,并设计了一系列实验进行探究:

实验(1):在两支试管中分别加入10mL等浓度的草酸溶液,在②号试管中加入少量硫酸锰固体。然后在两支试管中分别加入5滴0.1 mol·L-1的硫酸酸化高锰酸钾溶液。现象如下(表1)

 ①号试管②号试管
加入药品草酸溶液

硫酸酸化高锰酸钾溶液

草酸溶液

硫酸酸化高锰酸钾溶液

硫酸锰固体

实验现象(褪色时间)溶液褪色很慢(30s)溶液褪色很快(2s)
实验(2):在两支试管中分别加入5 mL等浓度的草酸溶液,在②号试管中再滴加10滴稀硫酸,然后各加入5滴0.1 mol·L-1的高锰酸钾溶液。现象如下(表2)

编号①号试管②号试管
  褪色时间

现象

100 s90 s
均有气泡产生;②号试管的溶液褪色比①号试管的溶液快,它们颜色变化如下:紫红色→红色→橙红色→橙色→黄色→无色。
实验(3):取3支试管分别加入5 mL等浓度草酸溶液,然后在①、②、③号试管中依次加入10滴、1 mL、2 mL稀硫酸溶液,各加入5滴0.1 mol·L-1的高锰酸钾溶液,然后置于温度为65℃的水浴中加热。观察现象(表3)。

编号①号试管②号试管③号试管
褪色时间

实验现象

80 s100 s120 s
均有气泡产生;①号试管的溶液褪色比②、③号试管的溶液快,它们颜色变化如下:紫红色→红色→橙红色→橙色→黄色→无色。
(1)该研究性学习小组的实验目的是                            

(2)该研究性学习小组进行实验时所用的方法是科学实验中常用的一种方法,该方法叫              法;

(3)实验(1)得出的结论是                                 

(4)由实验(2)和实验(3)得出的结论是(写三点)

_________________________,_____________________,_______________;

(5)据有关现象写出草酸溶液与酸性高锰酸钾溶液反应的离子方程式:

  H2C2O4  MnO4        Mn2           H2O

答案

(1)研究温度、浓度、催化剂等因素对化学反应速率的影响(2分)。

(2)对照实验法或者控制变量法(2分)

(3)结论:Mn2+在反应中起到催化剂的作用,加快了反应速率 。(2分)

(4)硫酸对草酸和高锰酸钾溶液的反应有影响。(2×3=6分)--答对其中3项得分

加入少量硫酸,可以促进草酸和高锰酸钾溶液的反应;

加入大量硫酸,草酸和高锰酸钾溶液的反应速率开始比较慢;

温度升高,反应速率加快 。

(5)  5 H2C2O4  2 MnO4  6 H+  2 Mn2+ 10CO2  8 H2O

阅读理解

阅读理解。

     As a teacher, I think it is right to tell my students to write about their pure feelings and real experiences. I always taught my students how to learn by experience. And I also found that it helped me a lot to get on well with the students.

     One day after explaining a text,I asked my students to write a passage about their families.I encouraged them to write about their  real  experiences  with  their closest family members. All the students wrote quite well  but  the  best one of them was written by a  little girl. She was Hao Fang. I was deeply moved by her

story. In  her  passage, she said her father  had died years  before  and  her mother  had to  work hard to

support the family. Many times she  had seen her mother work deep into night but never seen tears on her

face.  She also wrote that she needed to stay  strong  and  she would do the best to give her  mothe r an

easier life in the future. Like her mother, Hao  Fang also  worked hard  at  her  lessons  and she was really

good at any of them.  I didn't know anything about her unlucky family till then. She always appeared happy and 'never showed that she needed  anyone's help.

     In order to make her an example to the class, I read  this  passage to the class. When I finished reading

it, I found my throat choked  and  my students' eyes full of tears. After  class nearly  all  my  other students

crowded around Hao Fang and gave their money to help this girl. We knew her family needed money very much. Many students decided to offer her more help. To tell  the  truth, I was really proud  of my students.

But to my surprise, this student of mine didn't express her thanks to  her classmates and left school without even telling me the next day. I was puzzled about this.

     Was  it  right to  tell her sad story to the class? Why did sh e refuse to accept  the  donation? These

questions crowded my mind.

1. The teacher mentioned in the article always _      .         

A. made the students feel sad

B. asked the students to make up stories

C.  helped the students learn from the real life

2. Hao Fang wrote about her family's hard life in order to          .           

A. tell her real experiences

B. show how strong she was

C. ask her classmates for money

3. The underlined word "choked"  means          in Chinese.     

A.哽咽            

B.激动                

C. 疼痛

4. By reading the article, we know that Hao Fang _______ .      

A. appreciated the donation

B. was frustrated at her hard life

C. wanted to improve her family's life by working hard

5. We can learn from the article that       .             

A. the ways of helping people should be well chosen

B. it's wrong to ask students to tell their real experiences

C. donating money to the poor is the only better way to help them

单项选择题