问题 问答题

CO和CO2都可以合成甲醇:CO+2H2→CH3OH;CO2+3H2→CH3OH+H2O,CO、CO2和H2可通过下列反应制备:

①CH4+H2O(g)→CO+3H2

②CO+H2O(g)→CO2+H2

反应①的产物合成甲醇时H2过量,反应②的产物合成甲醇时H2不足.为了充分利用原料,可将两个反应的产物混合使用.

(1)反应①和反应②的产物气体混合的最佳比例为______.

(2)以CH4、CO、H2O混合气体为原料气,在一定条件下充分反应,所得气体用于合成甲醇,为使原子的利用率达到最高,则CH4、CO、H2O的最佳配比为______.

(3)若以100LCH4和H2O的混合气体为原料,制备CO、CO2和H2混合气体,当CH4和H2O均完全反应后,则在相同条件下反应后的气体的体积为______.(写出范围).

答案

(1)设反应①的气体产物共为V1L,则合成甲醇时H2过量0.25V1L,反应②的气体产物共为V2L,则反应②生成的气体中CO2体积为0.5V2L,H2的体积为0.5V2L,反应CO+2H2→CH3OH合成甲醇剩余的氢气,与反应②生成的混合气体恰好发生反应CO2+3H2→CH3OH+H2O,

故0.5V2L:(0.5V2L+0.25V1L)=1:3,整理得V1:V2=4:1,

故答案为:4:1;

(2)使原子利用率都达到100%,根据原子守恒,由甲醇的分子式可知,则混合气体中n(C):n(H):n(O)=1:4:1,

令CH4、CO、H2O的物质的量分别为xmol、ymol、zmol,则(x+y):(4x+2z):(y+z)=1:4:1,

整理得x:y:z=2:1:2,

故答案为:2:1:2;

(3)假定只发生反应CH4+H2O (g)→CO+3H2,生成的混合气体的体积最大,最大体积为100L×

4
2
=200L,假定只发生CH4+2H2O(g)→CO2+4H2,生成的混合气体的体积最小,最小体积为100L×
5
3
=166.7L,故反应后气体的体积为:166.7L<v<200L,

故答案为:166.7L<V<200L.

阅读理解

阅读理解。

     What does it mean to relax? Despite hearing this term thousands of times during the course of our lives,

very few people have deeply considered what it's really about.

     When you ask people what it means to relax, most will answer in a way that suggests that relaxing is

something you plan to do later-you do it on vacation, when you retire, or when you get everything done. This

means, of course, that most other times (the other 95 percent of your life) should be spent nervous, restless,

rushed, and mad. Could this explain why so many of us perform as if life were one great big emergency

(紧急事件)? Most of us put off relaxation until our " in-basket (收文篮)" is empty. Of course it never is.

     It is useful to think of relaxation as a quality of heart that you can own on a regular basis rather than

something left for some later time. You can relax now. It's helpful to remember that relaxed people can still be

super achievers and, in fact, that relaxation and creativity go hand in hand. When I'm feeling upright, for

example, I don't even try to write. But when I feel relaxed, my writing flows quickly and easily.

     Being more relaxed includes training yourself to react differently to the dramas (戏剧) of life-turning your

melodrama (情节剧) into a sweet-drama. It comes, in part, from reminding yourself over and over again

(with loving kindness and patience) that you have a choice in how you respond to life. You can learn to relate

to your thinking as well as your situation in new ways. With practice, making these choices will translate into

a more relaxed self.

1. The writer intends to tell us _____.

A. how to find chances to relas

B. what realxation really means

C. when to relax

D. the ways to relax

2. The underlined word " it" in the second paragraph (last sentence) probably refers to _____.

A. life

B. emergency

C. relaxation

D. in-basket

3. According to the passage most people think of relaxation as _____.

A. something planned to do in the future

B. something to be done now

C. something never to be done

D. something to be done like a dream

4. What is the writer's attitude towards relaxation?

A. Only by relaxing can one achieve something

B. No one really understands what relaxation is.

C. relaxation is a good state of mind one should keep every day.

D. 95 percent of your life should be spent in a relaxed way.

单项选择题