问题 选择题

甲醇质子交换膜燃料电池中将甲醇蒸气转化为氢气的两种反应原理是

①CH3OH(g)+H2O(g) = CO2(g)+3H2(g);DH=+ 49.0 kJ·mol1

②CH3OH(g)+1/2O2(g) = CO2(g)+2H2(g);DH =-192.9 kJ·mol1 下列说法正确的是

A.CH3OH的燃烧热为192.9 kJ·mol1

B.CH3OH的燃烧热为133.9 kJ·mol1

C.CH3OH转变成H2的过程一定要吸收能量

D.根据②推知反应:CH3OH(l) +1/2O2(g) = CO2(g) +2H2(g)的DH >-192.9 kJ·mol1

答案

答案:D

所谓燃烧热是指1mol物质完全燃烧生成稳定的氧化物所放出的热量,从所给方程式知道CH3OH转变成H2的过程可以是放热、也可以是吸热反应,但所示反应均不表示燃烧热。由于气态的甲醇的能量高于液态甲醇(如下图),所以可推出D选项正确。

阅读理解

阅读理解。

     Starting a stamp collection is easy and not very expensive. Before you start, you need to decide

what kind of stamps you want to collect. Most people collect stamps that they are interested in: a

certain country or an animal, a famous person or even a sport. Whatever you choose, you will find

that there is a world of knowledge in stamps: you will learn about people, geography, building, history

and culture.

     You can collect stamps from letters, ask your friends to let you have their old stamps, or you can

buy used stamps. When you get a letter with a stamp on it, carefully cut out the stamp. Leave lots of

space around the stamp so that you will not damage it. Put the stamp in water and wait until you can

safely remove the stamp. Carefully remove the stamp off the letter. Place the wet stamp between two

clean pieces of paper. A stamp can get wrinkled(褶皱的) when it dries, so put some books on top.

1. What does the writer think of collecting stamps?

A. Hard        

B. Expensive          

C. Useful          

D. Boring

2. What does the underlined work "damage" mean?

A. 损坏        

B. 保存              

C. 利用            

D. 删除

3.What's the correct order when we try to get a stamp on a letter?

①Remove the stamp off the letter.

②Place the wet stamp between two pieces of paper.

③Cut out the stamp.

④Put the stamp in water.

⑤Put some books on top.

A. ①→②→⑤→③→④                  

B. ③→④→①→②→⑤

C. ④→①→②→⑤→③                  

D. ③→①→④→②→⑤

填空题