问题 实验题

(12分)图示装置可用来制取和观察Fe(OH)2在空气中被氧化时的颜色变化。实验时必须使用铁屑和6mol·L-1的硫酸,其他试剂任选。填写下列空白:

(1)B中盛有一定量的NaOH溶液,A中应预先加入的试剂是          。A中反应的离子方程式是                          

(2)实验开始时先应将活塞D       (填“打开”“关闭”或“无关系”),C中收集到气体的主要成分是          

(3)简述生成Fe(OH)2的操作过程            

(4)拔去装置B中的橡皮塞,使空气进入,写出有关反应的化学方程式          

答案

(1)铁屑,Fe+2H=Fe2+H2↑  (2)打开,H2

(3)关闭活塞D,使FeSO4溶液压入B瓶中进行反应

(4)4Fe(OH)2+O2+2H2O=4Fe(OH)3

题目分析:(1)A装置是制取FeSO4的装置,所以先加入的试剂是铁屑,发生的离子反应为Fe+2H=Fe2++H2↑。

(2)实验开始时,应该先排除装置中的空气,所以应该先把活塞D打开,让产生的氢气充满整个装置。

(3)当整个装置充满氢气后,关闭活塞D,由于A中继续产生气体会将生成的FeSO4压入到B装置中,因此反应产生了Fe(OH)2

(4)空气进入会将Fe(OH)2氧化,其反应为:4Fe(OH)2+O2+2H2O=4Fe(OH)3

点评:本题的关键是要分析出活塞D的用处。

阅读理解

阅读理解。

     We all know the dangers of fires. It's good and necessary for a family to learn how to prepare for a fire.

Here are some suggestions. Put a smoke alarm (火警) in the house. Smoke from a fire causes the alarm to

go off. The alarm makes a loud sound. The sound tells everyone to leave the house at once.

     Make escape (逃脱) plans. We should know all the ways out of the house. If there is a fire, everyone

follows the plan to get out. Part of the plan is to check all the windows to make sure they can be opened

easily.

    Buy fire extinguishers (灭火器) in the house. Everyone in the family should know how to use them.

     Practise for a fire. We do fire practice because we teach children about fire safety. Everyone in the family

should know the following fire rules:

    ★ Don't open a hot door! The fire can grow more quickly if you open the door.

    ★ Stay close to the floor! Smoke can be more dangerous than fire. The best air is near the floor because

smoke rises.

    ★ What will you do if your hair or clothes start to burn? First, stop! Don't run! The fire burns faster

because of more air. Drop! Fall to the floor. Then roll! Turning over and over will make the fire go out. Put

a blanket (毯子) around you to keep air away from the fire that may still be on you.

    There are many possible causes for fires. A wise family is ready all the time. If there is a fire, don't forget

to call 119 for help.

1. When a smoke alarm rings at home, it means _________.

A. you have to get up

B. water is running to the floor

C. something is burning

D. someone breaks your window

2. The writer advises us to do the following to prepare for a fire except that _________.

A. we practise for a fire

B. we make escape plans

C. we buy fire extinguishers

D. we use electrical cookers

3. When a fire happens, _________ if you open the hot door.

A. the door will soon be on fire

B. the electricity will be cut off

C. the fire will grow more quickly

D. the house will fall down

4. What are the right steps you should take when your hair or clothes catch fire?

A. Stop, run, roll.

B. Stop, drop, roll.

C. Run, drop, roll.

D. Roll, drop, stop.

5. What is the best title for this passage?

A. Be Ready for a Fire.

B. The Causes of a Fire.

C. Learn to Use a Fire Extinguisher.

D. The Dangers of a Fire.

选择题