首页
登录
职称英语
About a century ago, the Swedish physical scientist Arrhenius proposed a low
About a century ago, the Swedish physical scientist Arrhenius proposed a low
游客
2024-04-22
42
管理
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. [br] 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://tihaiku.com/zcyy/3565953.html
相关试题推荐
Aboutacenturyago,theSwedishphysicalscientistArrheniusproposedalow
Aboutacenturyago,theSwedishphysicalscientistArrheniusproposedalow
Aboutacenturyago,theSwedishphysicalscientistArrheniusproposedalow
Before1965manyscientistspicturedthecirculationoftheocean’swaterma
Here’sawarningfromhealthexperts:Sittingisdeadly.Scientistsareinc
Here’sawarningfromhealthexperts:Sittingisdeadly.Scientistsareinc
[originaltext]Scientistsarefascinatedbywhattheylearnfromthemethods
[originaltext]Scientistsarefascinatedbywhattheylearnfromthemethods
Childrenarenatural-bornscientists.Theyhave【C1】______minds,andtheyare
Childrenarenatural-bornscientists.Theyhave【C1】______minds,andtheyare
随机试题
Theethicalbehaviorrefersto______.[br]Inthispassagetheauthorreallycon
下列句子中,加点的字不属于通假字的是( )。 A.张良出,项伯 B.距
在新民主主义革命和社会主义建设的重要关头,中国共产党成功地完成了三次重大转变:武
小明发现主机故障声不响,需要进行()操作来检查主机是否正常。A.消音 B.
基金销售机构销售基金产品一般以()营销理论为指导。A.4Cs B.4Ps
咳血方与小蓟饮子中均含有的药物是( )。A.山栀子 B.青黛 C.炙甘草
下列关于设计总负责的描述正确的是()。A:所谓设计总负责,就是指业主将一个建设
张某挎一背包到某工厂找人,遇到门卫王某的阻拦并发生争吵,引来群众围观。工厂保安发
缓冲区A.包括上下颌牙槽嵴顶的区域,能承担咀嚼压力,抵抗义齿基托的碰撞B.上下颌
无毒、抗菌卫生,主要用作工业及生活饮用水,冷、热水输送的管道是指()A.丁烯管
最新回复
(
0
)