问题 问答题

中考前,我市各校进行了化学实验操作考查,一些同学用图所示装置制备常见气体.请回答下列问题:

(1)写出图中标号①和②的仪器名称:______、______.

(2)小明用上图B、D装置制取一种常见气体.

①请写出有关反应的化学方程式______.

②检查装置的气密性:先将B装置的导管浸入水中,然后用手握住试管外壁,观察到导管口______(填“有”或“没有”)气泡冒出,表明B装置肯定会漏气.

③如何检验D中的气体已收集满?请写出有关的操作和现象______.

(3)小红同学用A、E装置和高锰酸钾制取并收集气体,要等到有连续稳定气泡冒出时才开始收集,而不是一看到气泡冒出就收集气体,其原因是______.

答案

(1)①是酒精灯,②是集气瓶;

(2)B装置不需要加热,说明反应物有液体,D装置为向上排空气法,说明该气体密度比空气大,常见的有二氧化碳,氧气等,综合考虑,该装置可以是双氧水制氧气,可以是实验室制二氧化碳,反应方程式为2H2O2

 MnO2 
.
 
2H2O+O2↑或CaCO3+2HCl═CaCl2+H2O+CO2↑;检查气密性时,如果装置漏气,则不会有气体从导管口冒出;如果收集的是氧气,验满应该用带火星的木条放在集气瓶口,木条复燃;如果收集的是二氧化碳,验满应将燃烧着的木条放在集气瓶口,木条熄灭;

(3)不能一开始看到有气泡冒出就收集,应为发生装置中的气体要先排出,否则气体不纯.

故答案为:(1)①酒精灯  ②集气瓶

(2)①2H2O2

 MnO2 
.
 
2H2O+O2↑或CaCO3+2HCl═CaCl2+H2O+CO2

②没有

③将带火星的木条放在集气瓶口,木条复燃;或将燃烧着的木条放在集气瓶口,木条熄灭(说明:此空要与?处的答案相对应.若不对应,或?处没填写,此空不给分)

(3)刚开始排出的是空气(或防止收集到的气体不纯;或试管中原来有空气等合理答案均可)

完形填空
As a famous American writer, Mark Twain, once said, “Everybody talks about weather, but nobody       anything about it.” It is true that everybody talks about the weather. Many people
   their talks by saying, “Isn’t it a nice       ?” “Do you think it will rain?” “I think it’s going to snow.”
A large number of people think they can tell        the weather is going to be like. However, they       ever agree with each other. One man may say, “Do you see how cloudy it is in the east? It’s going to rain tomorrow.” Another man       say, “Yes, it’s cloudy in the east. We are going to have fine weather tomorrow.”
People often look for the weather they want. When a farmer needs water, he looks for something to tell him it’s going to rain and he won’t believe        else. When friends have a picnic, they are so        the weather is going to be fine that they sit        their lunch while it is raining.
Almost everyone listens to what the weatherman says. But he doesn’t always tell us what we want and sometimes he makes a mistake. Still, he is       most of the time.
小题1:
A.doB.didC.does D.done
小题2:
A.beginsB.beginC.startsD.beginning
小题3:
A.dayB.weatherC.thingD.hour
小题4:
A.howB.whenC.whereD.what
小题5:
A.neverB.allC.almostD.hardly
小题6:
A.willB.wouldC.canD.may
小题7:
A.somethingB.anythingC.everythingD.nothing
小题8:
A.trueB.certainlyC.sureD.surely
小题9:
A.eatB.eatingC.eatsD.ate
小题10:
A.rightB.wrongC.mistakeD.all right
多选题