首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
About a century ago, the Swedish physical scientist Arrhenius proposed a low of classical chemistry that relates chemical reacti
About a century ago, the Swedish physical scientist Arrhenius proposed a low of classical chemistry that relates chemical reacti
admin
2015-01-31
26
问题
About a century ago, the Swedish physical scientist Arrhenius proposed a low of classical chemistry that relates chemical reaction rate to temperature. According to his equation, chemical reactions are increasingly unlikely to occur as temperature approaches absolute zero, and at absolute zero, reactions stop. However, recent experiment evidence reveals that although the Arrhenius equation is generally accurate in describing the kind of chemical reaction that occurs at relatively high temperature, at temperatures closer to zero a quantum-mechanical effect known as tunneling comes into play; this effect accounts for chemical reactions that are forbidden by me principles of classical chemistry. Specifically, entire molecules can tunnel through the barriers of repulsive forces from other molecules and chemically react even though these molecules do not have sufficient energy, according to classical chemistry, to overcome the repulsive barrier.
The rate of any chemical reaction, regardless of the temperature at which it takes place, usually depends on a very important characteristic known as its activation energy. Any molecule can be imagined to reside at the bottom of a so-called potential well of energy. A chemical reaction corresponds to the transition of a molecule from the bottom of one potential well to the bottom of another. In classical chemistry, such a transition can be accomplished only by going over the potential barrier between the well, the height of which remains constant and is called the activation energy of the reaction. In tunneling, the reactings molecules tunnel from the bottom of one to the bottom of another well without having to rise over the barrier between the two wells. Recently researchers have developed the concept of tunneling temperature: the temperature below which tunneling transitions greatly outnumber Arrhenius transitions, and classical mechanics gives way to its quantum counterpart.
This tunneling phenomenon at very low temperatures suggested my hypothesis about a cold prehistory of life: formation of rather complex organic molecules in the deep cold of outer space, where temperatures usually reach only a few degrees Kelvin. Cosmic rays might trigger the synthesis of simple molecules, such as interstellar formaldehyde, in dark clouds of interstellar dust. Afterward complex organic molecules would be formed, slowly but surely, by means of tunneling. After I offered my hypothesis, Hoyle and Wickramashinghe argued that molecules of interstellar formaldehyde have indeed evolved into stable polysaccharides such as cellulose and starch. Their conclusions, although strongly disputed, have generated excitement among investigators such as myself who are proposing that the galactic clouds are the places where the prebiological evolution of compounds necessary to life occurred.
In which of the following ways are the mentioned chemical reactions and tunneling reactions alike?
选项
A、In both types of reactions, reacting molecules have to rise over the barrier between the two wells.
B、In both types of reactions, a transition is made from the bottom of one potential well to the bottom of another.
C、In both types of reactions, reacting molecules are able to go through the barrier between the two wells.
D、In neither type of reaction does the rate of a chemical reaction depend on its activation energy.
答案
B
解析
细节题。根据“chemical reactions and tunneling reactions”定位到文章第二段In classical chemistry,such a transition can be accomplished only by going over thepotential barrier between the well,the height of which remains constant and is called theactivation energy of the reaction.In tunneling,the reacting molecules tunnel from thebottom of one to the bottom of another well without having to rise over the barrierbetween the two wells.“在经典化学中,这种跃迁只有跨过两阱之间势垒才能完成。位垒之高度为常数(固定不变)。这种跃迁叫做能量活化。在隧道效应中作反应的分子从一个势阱的底部通到另一个势阱底部不需要上升跨越两阱之间的位垒。”可见经典化学定理和隧道效应中都有从一个潜在的势阱底部到另一个底部的转换。和选项B表述一致,所以B为正确答案。
转载请注明原文地址:https://kaotiyun.com/show/pGh7777K
0
大学英语六级
相关试题推荐
A、Putupposters.B、Writeaspeech.C、Answerquestions.D、Studychemistry.B细节题。对话中女士提到,她安排了男士明天中午作演讲(giveaspeech),男士回答说他得尽快写一
NewtechnologylinkstheworldasneverbeforeOurplanethas【B1】______.It’snowa"globalvillage"wherecountriesareonlyse
NewtechnologylinkstheworldasneverbeforeOurplanethas【B1】______.It’snowa"globalvillage"wherecountriesareonlyse
NewtechnologylinkstheworldasneverbeforeOurplanethas【B1】______.It’snowa"globalvillage"wherecountriesareonlyse
NewtechnologylinkstheworldasneverbeforeOurplanethas【B1】______.It’snowa"globalvillage"wherecountriesareonlyse
NewtechnologylinkstheworldasneverbeforeOurplanethas【B1】______.It’snowa"globalvillage"wherecountriesareonlyse
A、Midnineteenthcentury.B、Latenineteenthcentury.C、Mideighteenthcentury.D、Lateeighteenthcentury.A短文谈到,美国有很多中国餐馆,超市里也卖中
A、Amancarefulwithmoney.B、Abook-lover.C、Anoisyreader.D、Atrouble-maker.A选项表明,本题考查人物性格或爱好等。由对话中男士提到的BeforeIpaymymon
Thelongestbullruninacenturyofart-markethistoryendedonadramaticnotewithasaleof56worksbyDamienHirst,"Beaut
Britishscientistsarebreedinganewgenerationofriceplantsthatwillbeabletogrowinsoilcontainingsaltwater.Theirw
随机试题
患者,男,46岁。反复心悸不宁3年,症见心悸少寐,多梦,头晕目眩,手足心热,耳鸣腰酸,舌红少苔,脉细数。问题4:(假设信息)若见虚烦咽燥,口干口苦等热象较著者,治疗应首选
关于医嘱的描述,不正确的是
某市西部拟建一污水处理厂,一期规模为30万t/d。污水处理厂退水为某市一条主要河流的河道。该地区夏季主导风向为西北风,冬季主导风向为东北风。污水处理厂厂址有两个备选方案:A.余粮堡村厂址;B.小梁厂址。A方案厂址位于某市洪区余粮堡村农田和浑河南岸滩地,东南
发展多种形式规范、健全的资本市场,尤其是(),提高企业直接融资比重,有效分流储蓄资金,减少企业外部融资对银行间接融资方式的过渡依赖。
隧道施工现场一般将风枪支撑在钻孔台架上,利用台架的钢管作为风管向风枪供送高压风。高压风的风压一般不低于()MPa,每台风枪每分钟的需风量不低于()m3。
古代筑垣以设境界而于其中饲养禽兽的场所称为()。
抑景主要有()之分。
人们都喜爱观赏日出,无不赞叹太阳升起时的壮观景象。而对日落,却很少有人去流连观赏、吟咏描绘。原因何在?恐怕是一种感情的影响,“日薄西山,气息奄奄”。就连我们的古人不也留下________的诗句吗?填入画横线部分最恰当的一句是()。
茶树性喜潮湿,需要多量而均匀的雨水,湿度太低或降雨量少于1500毫升都不适合茶树的生长。仙人球喜阳,只有在足够的光照下,才能发育良好,否则,会使条形圆球儿长成桶形,强刺球儿的刺也会萎缩,整个球没有光泽。在某地的大部分地区茶树和仙人球至少有一种长得好。如果
信息系统软件运维的主要过程不包含___________。
最新回复
(
0
)