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问题 问答题

某实验小组模拟高炉炼铁的化学反应原理进行实验，其装置如下图所示，请回答下列问题．

（1）A处通入气体的化学式为______，仪器C的名称是______，C中盛有的试剂是______；

（2）B处发生反应的化学方程式是______；该套装置的不足之处是______；

（3）向20g赤铁矿粉通入足量气体，充分反应后，获得11.2g铁，则赤铁矿石中三氧化二铁的质量分数为______．

答案

（1）炼铁是利用了一氧化碳的还原性，所以A处通入的气体为一氧化碳，而C仪器的名称为试管，为了验证是否生成了二氧化碳，所以在试管中应该装入的试剂为氢氧化钙溶液；

（2）炼铁的原理为用一氧化碳作为还原剂，在高温的条件下将铁还原出来，该反应生成了铁和二氧化碳，但是由于一氧化碳的利用率难以达到100%，所以为了防止有毒的一氧化碳直接排放到空气中，引起空气的污染，应该在最后加上尾气处理装置，而本题图中没有尾气处理装置；

（3）设获得11.2g铁需要三氧化二铁的质量为x，则：

Fe2O3+3CO

 高温 
.
 
2Fe+3CO2 

160             112

x                11.2g

160
112
=
x
11.2g

解得：x=16g

所以赤铁矿石中三氧化二铁的质量分数为：

16g
20g
×100%=80%．

答：赤铁矿石中三氧化二铁的质量分数为80%．

故答案为：（1）CO； 试管；澄清石灰水（或Ca（OH）2溶液）；

（2）Fe2O3+3CO

 高温 
.
 
2Fe+3CO2；没有进行尾气处理；

（3）80%．

问答题 论述题

简述卢梭的社会契约理论的主要内容。
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单项选择题

A


Napoga is a 12-year-old girl in Ghana(加纳), Africa. It is hard for her family to get clean water. Every morning, she leaves home at half past five to get clean water for her family in a village far away. It takes her six hours to get enough clean water for daily (日常的) cooking and drinking. She has no time to go to school or to play with her friends. Millions of people in the world are like Napoga. They can’t get enough clean water to keep healthy.
Earth Day is April 22. But on all other days, we must also remember it. The water we use is the most important natural resource(自然资源) on the earth.
Water covers 70% of the earth’s surface(表面). But most of that is sea water. We can’t use it for very many things. Fresh water covers only 1% of the earth’s surface.
You probably feel lucky that your life isn’t as hard as Napoga’s. But that doesn’t mean you don’t have to worry about water. We all face serious water problems. One of them is water pollution. All kinds of things from cars, factories, farms and homes make our rivers, lakes, and oceans dirty. Polluted water is very bad for people to drink. And dirty water is bad for fish, too. Now, 34% of all kinds of fish are dying out.
How do cars and factories make our water dirty First, they pollute the air. Then, when it rains, the rain water comes down and makes our drinking water dirty. Dirty rain, called acid rain (酸雨), is also bad for plants, animals and buildings.
Scientists say that in 30 years, more than half of the people in the world won’t have enough clean water. We have to learn how to save more water for ourselves and our children. Here is some advice for saving water:
Turn off the water while you brush your teeth. You can save as much as 450 liters (升) each month.
Leaky taps(水的龙头) waste a lot of water. Fix them right away!
You can easily cut your 1O-minute showers(沐浴) in half—and you’ll be just as clean.
When you wash dishes, don’t let the water run.
Only wash clothes when you have a lot to wash. If your washing machine isn’t full, you’re wasting water!

What’s the main idea of the passage ( )

A．Something must be done to prevent water form being polluted.

B．Clean water means much to human beings and living things around us.

C．It’s time to take care of the water we use.

D．Water is the most important natural resource on the eart
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