问题 实验题

化学课上老师做了一个演示实验:用脱脂棉包住约0.2g过氧化钠粉末,置于石棉网上,往脱脂棉上滴水,观察到脱脂棉剧烈燃烧起来。

(1)由上述实验现象所得出的有关过氧化钠跟水反应的结论是:

第一:有氧气生成;

第二:______________。

Na2O2跟水反应的化学方程式是________________________。

(2)某研究性学习小组拟用下图所示装置(气密性良好)进行实验,以证明上述结论。

用以验证第一条结论的实验操作是:___________________________;用以验证第二条结论的实验方法是:______________________________。

(3)实验(2)往试管中加水至固体完全溶解且不再有气泡生成后,取出试管,往试管中滴入酚酞试液,发现溶液先变红后褪色。为探究其原因,该小组同学从查阅有关资料中得知:Na2O2与水反应可生成H2O2,H2O2具有强氧化性和漂白性。

请设计一个简单的实验,验证Na2O2跟足量水充分反应后的溶液中有H2O2存在。(只要求写出实验所用的试剂及观察到的现象)试剂:_______________________;现象:____________________________。

(4)该小组同学提出用定量的方法探究Na2O2跟水反应后的溶液中否含有H2O2,其实验方法为:称取

2.6g Na2O2固体,使之与足量的水反应,测量产生O2的体积并与理论值比较,即可得出结论。

①测量气体体积时,必须待试管和量筒内的气体都冷却至室温时进行,应选用上图装置中的__________ (忽略导管在量筒中所占的体积)(填序号),理由是___________________。

②若在标准状况下测量气体的体积,应选用的量筒的大小规格为____________(选填“100mL”“200 mL”“500 mL”或“1000 mL”)。

答案

(1)该反应是放热反应;2Na2O2+2H2O==4NaOH+O2

(2)打开分液漏斗活塞使水流入试管,再将带火星的木条靠近导管口P处,木条复燃,证明有O2生成;将导管Q浸入水中,反应过程中导管口有气泡冒出

(3)MnO2;气泡迅速产生,能使带火星的木条复燃

(4)①B;防止气体冷却时发生倒吸现象;②500mL

阅读理解
BBC News on TV, radio and online often brings you stories from across the world. Today we can hear “Life in China”. Have you got a story about life in China today? If you do, please put your stories here.
Wu Peng, Anhui

    I am a 14-year-old boy from a poor village in Anhui Province. Like many other left-behind children in China, I live with my grandparents now. My parents went to work in Shanghai several years ago. They call me twice a month to ask about my study. I really miss my parents and I hope I can go to school in Shanghai. I think every child needs parents’ love and care.
Cindy, Shenzhen

I like traveling and I have traveled a lot around China. During the trip, I often find that a number of Chinese often break the rules in public. For example, when I traveled in Hong Kong this year, I saw a kid eating noodles on the underground, which was against the rules. However, the kid’s mother didn’t think she did wrong. Can you believe it? Let’s improve our public manners.
Mike, Shanghai

These days, we’re asked to “clear our plates” when having our meals and say no to wasting. Some of us used to order more than what we could eat. That was a big waste of food. Now we need to finish the food we order. We should also stop wasting in some other ways. For example, we should turn off the lights when we leave the classroom.
小题1:How does Wu Peng contact his parents according to the passage?
A.By writing letters.B.On the telephone.
C.On the Internet.D.By sending text messages.
小题2:Who thought it was not right to eat on the underground?
A.Cindy.B.Mike.C.Wu Peng.D.The kid’s mother
小题3:What does Mike want people to do?
A.Care about left-behind childrenB.Obey the rules in public.
C.Improve their public mannersD.Stop wasting
单项选择题