GRE阅读题目解析:化学反应与温度相关性

　　P2

　　1

　　About a century ago, the Swedish physical scientist Arrhenius proposed a law of classical chemistry that relates chemical reaction rate to temperature.

　　大约一百年前，瑞典物理学家 A 提出一条经典化学的规律，化学反应与温度之间存在相关性。

　　2

　　According to the Arrhenius equation, chemical reaction are increasingly unlikely to occur as temperatures approach absolute zero, and at absolute zero (zero degrees Kelvin, or minus 273 degrees Celsius) reactions stop.

　　根据 A 的推导，温度越接近绝对零度，化学反应越难发生，达到绝对零度(开尔文 0 度，或摄氏零下 273 度)化学反应停止。

　　3

　　However, recent experimental evidence reveals that although the Arrhenius equation is generally accurate in describing the kind of chemical reaction that occurs at relatively high temperatures, 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 the principles of classical chemistry.

　　然而，最近有实验证据显示，尽管 A 的方程在描述较高温度环境下的化学反应时通常精确，但温度降至接近绝对零度时，量子力学效应或称隧道效应(势垒贯穿)开始发挥作用;这种效应解释了，经典化学理论认为不可能发生的某些反应。

　　4

　　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.

　　特别是整个分子能够 “ 通过隧道 ” 穿过其他分子的斥力产生的势垒，并发生反应，即便根据经典化学理论，前者没有足够的能量来克服势垒。

　　5

　　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.

　　任何化学反应的速率，不考虑反应发生时的温度，通常依赖一种非常重要的特征指标，即活化能。

　　6

　　Any molecule can be imagined to reside at the bottom of a so-called potential well of energy.

　　我们可以想象，任何分子都处于所谓势能井的底部。

　　7

　　A chemical reaction corresponds to the transition of a molecule from the bottom of one potential well to the bottom of another.

　　化学反应相当于分子从一个势能井底部移动到另一个的底部。

　　8

　　In classical chemistry, such a transition can be accomplished only by going over the potential barrier between the wells, the height of which remains constant and is called the activation energy of the reaction.

　　经典化学理论中，这样的转移只能通过克服井间的势垒来完成，势垒的高度恒定，被称为该反应的活化能。

　　9

　　In tunneling, the reacting molecules tunnel from the bottom of one to the bottom of another well without having to rise over the barrier between the two wells.

　　隧道效应中，反应分子通过隧道从一个势能井底部到达另一个，无需克服两井之间的势垒。

　　10

　　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.

　　近期，研究者发展了隧道温度的概念：达到该温度或更低温度时，隧道转移极大超过 A 式转移，经典化学理论失效，量子化学理论发挥作用。

　　11

　　This tunneling phenomenon at very low temperatures suggested my hypothesis about a cold prehistory of life: the formation of rather complex organic molecules in the deep cold of outer space, where temperatures usually reach only a few degrees Kelvin.

　　这种低温下的隧道现象启发我提出了生命物质在低温下的形成假设：在极寒的宇宙空间，温度只比开氏零度高一些，形成了相当复杂的有机分子。

　　12

　　Cosmic rays (high-energy protons and other particles) might trigger the synthesis of simple molecules, such as interstellar formaldehyde, in dark clouds of interstellar dust.

　　宇宙射线(高能质子和其他粒子)可能激发了简单分子的化合作用，比如星际间的甲醛，被发现于星际尘埃形成的暗云中。

　　13

　　Afterward complex organic molecules would be formed, slowly but surely, by means of tunneling.

　　然后会形成复杂的有机分子，慢但肯定会发生，以隧道反应的方式。

　　14

　　After I offered my hypothesis, Hoyle and Wickramasinghe argued that molecules of interstellar formaldehyde have indeed evolved into stable polysaccharides such as cellulose and starch.

　　我提出假设后，H 和 W 认为星际甲醛分子实际上变成了稳定的多糖比如纤维素和淀粉。

　　(argue 一方面可以指与人争执，吵起来了;一方面也可以指，为自己的观点提供证据和逻辑，来说服别人。

　　所以不要一看到 argue 就认定对方提出了一种反驳观点。从本文来看，H 和 W 主张的观点跟文中的 “我” 就不矛盾，只不过把我的假设又推前了一步，引起的争议也看不出是我提出或支持的。)

　　15

　　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.

　　尽管他们的结论引发了强烈争议，但也让包括我在内的许多研究者兴奋不已，我们都认为，星云是生命出现以前的演化过程中，必要化合物的诞生地。

　　2.According to the passage, classical chemical reactions and tunneling reactions are alike in which of the following ways?

　　(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 neither type of reaction does the height of the barrier between the wells remain constant.

　　(D) In neither type of reaction does the rate of a chemical reaction depend on its activation energy.

　　(E) In both types of reactions, reacting molecules are able to go through the barrier between the two wells.

　　选 B

　　A 错。一个越过，一个穿过。

　　B 正确。都是一个底到另一个底。

　　C 错在 neither 。两者的 barrier 都是恒定的，只不过 tunneling 不需要越过 barrier 了。

　　D 错在 nether 。一个需要考虑活化能，一个不需要。

　　E 错。经典的不能 go through 。

　　3.The author's hypothesis concerning the cold prehistory of life would be most weakened if which of the following were true?

　　(A)Cosmic rays are unlikely to trigger the formation of simple molecules.

　　(B)Tunneling occurs only in a narrow band of temperatures around zero degrees Kelvin.

　　(C)The synthesis of interstellar formaldehyde can be activated by means other than cosmic rays.

　　(D)Simple molecules can be synthesized by means of tunneling.

　　(E)Classical chemical reactions do not occur at temperatures close to absolute zero.

　　选 A

　　A 正确。如果宇宙射线不能激发简单分子化合，那么整个假设就不存在了。

　　B 不确定项。narrow 是个很模糊的说法，如果这个 narrow 能包括句 11 末的 only a few degrees Kelvin，假设仍然成立，所以说不确定。

　　C 错误项。除了宇宙射线，其他方式也能促进化合。这不但不能攻击作者的假设，甚至给作者的假设提供了一定的保险。

　　D 错。文中作者假设的基础，正是这种情况，再说一遍也不能 weaken 之。

　　E 错。同 D，这也是作者承认的先决条件，假设说的是通过 tunneling，跟经典化学无关。

　　4.Which of the following best describes the hypothesis of Hoyle and Wickramasinghe as it is presented in the passage?

　　(A) Cosmic rays can directly synthesize complex organic molecules.

　　(B) The galactic clouds are the places where prebiological evolution of compounds necessary to life occurred.

　　(C) Interstellar formaldehyde can be synthesized by tunneling.

　　(D) Molecules of interstellar formaldehyde can evolve into complex organic molecules.

　　(E) Complex organic molecules can be synthesized from stable polysaccharides such as cellulose and starch.

　　选 D

　　简单总结一下句 11-15：

　　作者认为，通过隧道效应，宇宙射线在低温环境激发了简单分子化和成简单有机分子，比如甲醛，甲醛一定会进一步化合成更复杂的有机分子;

　　H 和 W 不但同意我的假设，他们甚至进一步推演，认为星际甲醛变成了稳定的多糖，比如纤维素和淀粉。

　　A 错在 derectly 。而且这也不是二人的观点，而是作者的观点。

　　B 错，这是对二人观点感兴趣的科学家们的猜测。

　　C 错，这是作者提出的。

　　D 正确。

　　E 错，二人只提出了甲醛到多糖，没说多糖到更复杂的有机分子。

　　5.Which of the following best describes the organization of the first two paragraphs of the passage?

　　(A) The author cites a basic principle of classical chemistry and then describes the research from which that principle was developed.

　　(B) The author cites an apparent contradiction to the principles of classical chemistry and then explains the process of a chemical reaction to show there is in fact no contradiction.

　　(C) the author describes the role of heat in chemical reactions and then offers a detailed explanation of its function.

　　(D) The author presents a law of classical chemistry in order to introduce a kind of chemical reaction that differs from it and then explains the essential difference between the two.

　　(E) The author presents the fundamental rules of classical chemistry in order to introduce an explanation of a specific chemical reaction.

　　选 D

　　没说的。

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