问题 填空题

(10分)设计出燃料电池使天然气CH4氧化直接产生电流是对世纪最富有挑战性的课题之一。最近有人制造了一种燃料电池,一个电极通入空气,另一电极通入天然气,电池的电解质是掺杂了Y2O3的ZrO2晶体,它在高温下能传导O2离子。回答如下问题:

(1)这个电池的正极发生的反应是:                                ;(2分)

(2)负极发生的反应是:                                             ;(2分)

(3)固体电解质里的O2的移动方向是:                               ;(2分)

(4)天然气燃料电池最大的障碍是氧化反应不完全,产生         堵塞电极的气体通道,有人估计,完全避免这种副反应至少还需10年时间,正是新一代化学家的历史使命。(2分)

(5)若将此甲烷燃料电池设计成在25%的KOH溶液中的电极反应,该电池的负极区域的碱性会__________(填“增强”、“减弱”或“不变”)。(2分)

答案

(1)O2+4e-=2O2-(2分)   (2)CH4-8e-=CO2+2H2O(2分)

(3)正极流向负极(2分) (4)碳(2分)    (5)减弱(2分)

(1)原电池中正极得到电子,所以氧气在正极通入。又因为电解质是掺杂了Y2O3的ZrO2晶体,它在高温下能传导O2离子,所以正极电极反应式为O2+4e-=2O2-

(2)负极失去电子,因此甲烷在负极通入,甲烷的氧化产物是CO2和水,所以电极反应式为CH4-8e-=CO2+2H2O。

(3)原电池中,负极失去电子,所以阴离子流向负极。

(4)甲烷不完全反应,可能产生碳单质堵塞电极的气体通道。

(5)如果电解质是氢氧化钠,则负极电极反应式为H2-2e+2OH=2H2O,所以负极周围溶液的碱性减弱。

选择题
填空题

阅读理解。

    We know the mosquito (蚊子) very well. Mosquitoes fly everywhere. They can be found almost all

over the world, and there are more than 2,500 kinds of them.    

     No one likes the mosquito. But the mosquito may decide that she loves you. She? Yes, she. It's true

that the male mosquito doesn't bite (咬) and only the female mosquito bites because she needs blood to

lay eggs. She is always looking for things or people she wants to bite. If she likes what she finds, she

bites. But if she doesn't like your blood, she will turn to someone else for more delicious blood. Next

time a mosquito bites you, just remember you are chosen. You're different from the other people!    

     If the mosquito likes you, she lands on your body without letting you know. She bites you so quickly

and quietly that you may not feel anything different. After she bites, you will have an itch on your body

because she puts something from her mouth together with your blood. By the time the itching begins, she

has flown away.  

     And then what happens? Well, after her delicious dinner, the mosquito feels tired. She just wants to

find a place to have a good rest. There, on a leaf or a wall, she begins to lay eggs, hundreds of eggs.

1. "itch" means ______ in Chinese.

A. 叫声  

B. 麻木  

C. 剧痛  

D. 痒

2. How many kinds of mosquitoes are there in the world?             

A. There are 2,500 kinds of them.    

B. There are more than 2,500 kinds of them.    

C. There are many kinds of them.    

D. There are less than 2,500 kinds of them.

3. "But the mosquito may decide that she loves you." "she" refers  to (指的是) ______.

A. the male mosquito         

B. the young mosquito    

C. the old mosquito          

D. the female mosquito

4. The mosquito is always looking for ______.   

A. people she dislikes    

B. things or people she doesn't want to bite    

C. things or people she wants to bite    

D. animals she doesn't want to bite

5. Which of the following sentences is true?  

A. The itching begins before the mosquito bites you.    

B. Mosquitoes need blood to lay eggs.    

C. You feel terrible when the mosquito bites you.    

D. All the mosquitoes like to bite people for blood.