问题 计算题

将28.12 g还原铁粉(含少量FexC)在氧气流中加热,得到标准状况下的CO2 224mL;将相同质量的还原铁粉与足量硫酸反应,得标准状况下的H2 10.752L,计算FexC的化学式。

答案

Fe2C           (4分)

题目分析:CO2的物质的量是0.224L÷22.4L/mol=0.01mol

氢气的物质的量是10.752L÷22.4L/mol=0.48mol

则单质铁的质量是0.48mol×56g/mol=26.88g

所以FexC的质量是28.12g-26.88g=1.24g

根据碳原子守恒可知,该化合物的物质的是0.01mol

则该化合物的相对分子质量是1.24÷0.01=124

所以x=(124-12)÷2=2

即化学式是Fe2C

点评:该题是基础性试题的考查,侧重对学生基础知识的巩固和训练,该题的关键是利用好守恒法,有利于培养学生的逻辑推理能力和创新思维能力。

单项选择题
阅读理解

A man accused of failing to return more than 700 children’s books to five different libraries in the county was released from prison after a book publisher agreed to post his bond(保释金)of $1,000.The publisher said.“There’s a story here.This is a man who loves books.He just can’t let go of them.He hasn’t stolen a single book.So what’s the crime ? We think that Mr.Banish has story to tell.We plan to publish his story.”  

When asked why he didn’t return the books, Mr.Banish said,”Well,how could I? They became family to me.I was afraid to return them,because I knew that kids or dogs would get hold of these books and chew them up,throw them around,tear the pages,spill soda on them,get jelly﹙糊状物﹚ on them,and drown them in the toilet.

He continued,“Books are people,too! They talk to you,they take care of you,and they enrich you with wisdom,humor and love.A book is a guest in my home.How could I kick it out? I repaired tor n﹙撕破的﹚ pages.I dusted them with a soft clean cloth.I turned their pages so they could breathe and get some fresh air.”

“Every week I reorganized them on their shelves so they could meet new friends,My books were HAPPY books.You could tell just by looking at them.Now they’re all back in the libraries,on the lower shelves,on the floors,at the mercy of all those runny-nosed kids I can hear them calling me.I need to rescue them.Excuse me.I have to go now.”

小题1:Why was the man put into prison?

A.Because the book publisher persuaded the police to do so.

B.Because he stole 700 children’s books from the five different libraries.

C.Because he refused to return the books that he had borrowed.

D.Because he wanted to publish his story.小题2:From the passage we can learn that the man is       

A.a thief

B.a writer

C.crazy about books

D.unfortunate小题3:What might happen after the man was set free?

A.He might stop borrowing books.

B.He might start a library of his own.

C.He might go on borrowing books from libraries.

D.He might return all his books.小题4:What is mainly talked about in this passage?

A.A funny thief who loves stealing books.

B.A person who refuses to return borrowed books and wants to look after them.

C.A person who is crazy about books so he keeps stealing them from the library.

D.A person who may have some mental problems