问题 填空题

0.2 mol有机物和0.4 mol O2在密闭容器中燃烧后的产物为CO2、CO和H2O(g)。产物经过浓硫酸后,浓硫酸的质量增加10.8 g;再通过灼热CuO充分反应后,固体质量减轻3.2 g;最后气体再通过碱石灰被完全吸收,碱石灰质量增加17.6 g。

(1)判断该有机物的化学式。

(2)若0.1 mol该有机物恰好与4.6 g金属钠完全反应,试确定该有机物的结构简式。(已知:一个碳上接两个羟基是不稳定的)

答案

(1) C2H6O2  (2) HOCH2CH2OH

题目分析:(1)浓硫酸的质量增加10.8 g,则水的质量是10.8g,水的物质的量为0.6mol,则0.2mol有机物中氢原子的物质的量是1.2mol;0.4 mol O2中氧原子的物质的量是0.6mol,通过灼热CuO充分反应后,固体质量减轻3.2 g,根据反应式CuO+CO=Cu+CO2可知,CO的物质的量为0.2mol,再通过碱石灰被完全吸收,碱石灰质量增加17.6 g,则CO2的质量是17.6g,物质的量为0.4mol,其中由CO生成的CO2是0.2mol,原有机物燃烧生成的CO2是0.4mol-0.2mol=0.2mol,根据氧原子守恒可知原有机物中氧原子的物质的量是0.6mol+0.2mol+0.2mol×2-0.4mol×2=0.4mol,该有机物的化学式只能是C2H6O2;(2)0.1 mol该有机物恰好与4.6 g金属钠完全反应,4.6g金属钠的物质的量是0.2mol,这说明有机物中含有2个羟基,该有机物的结构简式是HOCH2CH2OH。

阅读理解

阅读理解。

     Can you imagine a world without the Internet? It's amazing to think about it.

     Now, China has more than 68 million Internet users, according to the China Internet Network Information

Centre. This is the second highest number of users in the world after the United States. Today, 44% of

Chinese "netizens (网民)" are teenagers."They spend about 13 hours every week online," said Qian Hulin, an

Internet expert. 

     The main reasons why teenagers surf the Web are to search for information, to communicate with others

and to have fun. On the Internet, teenagers can find out almost anything. And surfing the Web can help

students with their homework and widen their knowledge.

     Li Dong, a teacher at No. 41 Middle School in Shijiazhuang, likes her students to use the Internet. "When

we talk in class, students who surf the Net usually know more background information than the others," she

said.

     In addition, people can use the Internet to write letters or stories and send emails. Many teens keep in

touch with their friends online. It is cheaper than phoning somebody far away and also much quicker.

1. Which country has the most Internet user?

A. China

B. England

C. America

D. Japan

2. How many hours do teenagers spend on the Internet every week?

A. About 44 hours

B. About 13 hours

C. About 41 hours

D. About 10 hours

3. Why do teenagers surf the Web?

A. To get some money

B. To search for information

C. To have fun

D. Both B and C

4. Why does the teacher from Shijiazhuang like her students to use the Internet?

A. Because she wants to play computer games with them.

B. Because she wants to have a talk with them.

C. Because she wants to know what they do at home.

D. Because she wants to let them know more background information.

5. Which way is the cheapest and quickest to tell something to your friend who is far away?

A. Posting a letter.

B. Sending an e-mail.

C. Making a telephone call.

D. Going to visit your friend.

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