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
2014-12-26
33
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.
According to the Arrhenius equations as discussed in the passage, which of the following statements about chemical reactions is true?
选项
A、Chemical reactions are less likely to occur at temperature close to absolute zero.
B、In some cases the rate of a chemical reaction is related to temperature and in other cases it is not.
C、The rate of a chemical reaction depends on many other factors besides temperature.
D、Chemical reaction rate and temperature are not related.
答案
A
解析
细节题。根据“Arrhenius equations”定位至文章第一段According to hisequation,chemical reactions are increasingly unlikely to occur as temperatureapproaches absolute zero,and at absolute zero,reactions stop.“根据他的定理,当温度越接近绝对零度,化学反应就越不可能发生;当到达绝对零度的时候,反应就停止了。”这和A选项表达一致。所以答案选A。
转载请注明原文地址:https://kaotiyun.com/show/6bh7777K
0
大学英语六级
相关试题推荐
Doeswalkingonthemoonmakelifebetterforpeopleonearth?Whyshouldwebespendinghugesumsontripstoouterspace?Such
Doeswalkingonthemoonmakelifebetterforpeopleonearth?Whyshouldwebespendinghugesumsontripstoouterspace?Such
A、Membershipinafoodco-op.B、Thebenefitsofhealthfood.C、Shoppinginthesupermarket.D、Thecurrentcostoffood.A对话开门见山地
A、Inacafe.B、Inapub.C、Inarestaurant.D、Inanightclub.B短文中提到Tomeetfriendshereitusuallyhastobeinapub,由此可知,在英国人
A、TheirBBSwasnotasgoodaswhattheyhadthoughtbefore.B、Theirprogressinthewebsite-designwashinderedforlackoffun
A、Becausetakingthesubwayisfasterthoughlessdirect.B、Becausetakingthesubwayislessexpensive.C、Becausetakingthebu
Amidweakjobandhousingmarkets,consumersaresavingmoreandspendinglessthantheyhaveindecades,andindustryprofessio
A、Tohelppeopleunderstandhorsesbetter.B、Tohelppeopleenjoyafamilyatmosphere.C、Tohelppeoplehavefunaboveotherthi
Thebiggestsafetythreatfacingairlinestodaymaynotbeaterroristwithagun,butthemanwithaportablecomputerinbusin
Forthousandsofyearsmanhasexploitedandoftendestroyedtherichesofland.Nowmancovets(觊觎)thewealthoftheoceans.Eve
随机试题
在薄板结构的装焊中,广泛采用________。
油箱的容量一般为液压泵流量的2~3倍。()
什么是堆焊?常用的堆焊方法有哪些?
Tobe,ornottobe—thatisthequestion;Whether’tisnoblerinthemindtosufferTheslingsandarrowsofoutrageousfortune
刑事诉讼中需要回避的人员不包括()
A.酸奶B.脱脂乳C.稀释乳D.无乳糖奶粉E.豆奶粉供新生儿和早产儿食用
决定信托产品收益和风险的主要因素是()。
根据下面材料回答以下问题。总体看来,2004年世界各国的石油探明储量基本变化不大。但是由于BP公司修正了前苏联、哈萨克斯坦、伊朗、利比亚和苏丹等国的数据,特别是哈萨克斯坦从12亿吨修正到54亿吨,从而使各国在全球石油储量分布中所占的比例发生了一些
通过经济手段征税,把碳排放作为一项成本,计入工业生产和个人生活中,在经济学上顺理成章,但在政治上却有着极大的风险。既难以得到工业界的支持,也不容易说服选民。虽然是以碳排放名义征税,却往往会被认为是政府变相加税,或者是通过人为增加成本来压缩市场需求,不得人心
下列网络系统要素中,网络攻击的主要目标是()。
最新回复
(
0
)