21世纪四大化学难题
高考化学常见难题解析与解答方法
高考化学常见难题解析与解答方法高考化学对大部分学生来说是一门难题，很多学生对此感到困惑。
为了帮助广大学生更好地应对高考化学，本文将分析常见的难题，并提供解析与解答方法。
1. 难题一：酸碱溶液的计算问题酸碱溶液的计算是高考化学考试中比较常见的问题。
其中一个经典问题是计算酸碱溶液的pH值。
解决这个问题需要掌握酸碱溶液的离子浓度和离子平衡原理。
通过计算酸碱离子浓度，利用pH=-log[H+]公式，就可以得到溶液的pH值。
2. 难题二：有机化合物的识别问题有机化合物的识别是高考化学考试中的重点难题之一。
面对一组化合物，我们需要根据给出的信息确定它的结构式或化学式。
解决这个问题需要熟悉有机化合物的命名规则和结构特征，同时还需要掌握一些常见的有机官能团的化学性质。
3. 难题三：电化学问题电化学作为高考化学中的一个重要知识点，对很多学生来说是一个难点。
在解决电化学问题时，我们需要了解电池的构成及原理，电化学反应的规律，以及在电化学过程中的电流方向和氧化还原反应的方向。
通过掌握这些知识，我们能够准确地判断电池和电化学反应的产物。
4. 难题四：配位化合物的性质问题配位化合物是高考化学中经常出现的一个考点，也是很多学生的难题。
在解决配位化合物的性质问题时，我们需要理解配位化合物的结构和确定中心金属离子的价态与配位数，并了解轴向配体和配位环境对配位化合物性质的影响。
5. 难题五：化学反应的速率问题化学反应的速率问题是高考化学中一个重要的考点。
解决这个问题需要掌握反应速率与反应物浓度和温度的关系，了解催化剂对反应速率的影响，以及掌握酶和催化剂的特性和作用机制。
通过解析以上几个常见难题，我们可以找到一些解答方法，以帮助学生更好地应对高考化学。
首先，进行针对性复习。
对于每一个难题，我们需要有针对性地进行复习，将相关的知识点进行归纳总结，并通过练习题来加强对难题的理解。
其次，理清思路。
在解答难题时，我们需要按照一定的思路进行分析与解答。
史上最难化学试题及答案
史上最难化学试题及答案1. 问题：请解释什么是共价键，并给出一个例子。
答案：共价键是一种化学键，其中两个原子共享一对电子以满足它们的最外层电子的稳定状态。
例如，水分子（H2O）中的氢原子和氧原子之间形成的就是共价键。
2. 问题：什么是酸碱中和反应？请写出其化学方程式。
答案：酸碱中和反应是一种化学反应，其中酸和碱反应生成盐和水。
一个典型的酸碱中和反应的化学方程式是：\[ \text{HCl} + \text{NaOH} \rightarrow \text{NaCl} +\text{H}_2\text{O} \]3. 问题：请描述电子排布在原子中是如何进行的。
答案：电子在原子中按照特定的能级和亚能级进行排布，遵循泡利不相容原理和洪特规则。
最外层电子数不超过8个，次外层不超过18个，倒数第三层不超过32个。
4. 问题：什么是氧化还原反应？请给出一个例子。
答案：氧化还原反应是一种化学反应，其中至少有一个元素的氧化态发生变化。
例如，铁与氧气反应生成铁的氧化物：\[ 4\text{Fe} + 3\text{O}_2 \rightarrow2\text{Fe}_2\text{O}_3 \]5. 问题：请解释什么是同位素，并给出一个例子。
答案：同位素是具有相同原子序数但不同质量数的原子，它们具有相同数量的质子但中子数不同。
例如，氢的同位素有氕（H）、氘（D）和氚（T）。
6. 问题：什么是化学平衡？请解释勒夏特列原理。
答案：化学平衡是指在一个封闭系统中，正向反应和反向反应的速率相等，反应物和生成物的浓度不再随时间变化的状态。
勒夏特列原理指出，如果一个处于平衡状态的系统受到外部条件的改变（如浓度、压力、温度），系统会自发地调整以减小这种改变的影响。
7. 问题：请解释什么是摩尔，并给出摩尔质量的定义。
答案：摩尔是物质的量的单位，表示物质中包含的粒子数与12克碳-12中包含的碳原子数相同。
摩尔质量是一摩尔物质的质量，通常以克/摩尔（g/mol）为单位。
化学世界的10大未解之谜
化学世界的10大未解之谜绝大部分最精深的科学问题，以及一些对人类而言最为紧迫的问题，都与原子或者分子有关。
1.生命从何而来？距地球上第一种生物从无生命物质中诞生，至今已近40亿年，但最初的生命是如何出现的，至今仍是个谜。
那些相对简单的分子，最初如何从“原始汤”里创生出来，并形成越来越复杂的化合物？这些化合物又如何开始进行能量代谢，并完成自我复制（这两者是定义生命的两个特性）？当然，在分子水平上，所有这些步骤都是化学反应，也正因为如此，“生命从何而来”成了一个化学问题。
关于这个问题，对科学家的挑战不再是构想出那些看似合理的假说，因为这样的假说已经太多了。
例如，有研究者推断，在第一种能够自我复制的聚合物（类似DNA或蛋白质一类的分子，是由许多更小单位构成的长链）的形成过程中，泥土等矿物质可能起到了催化剂的作用。
还有人认为，正是因为深海热泉源源不断地提供能量，才会产生结构复杂的化学物质。
此外，还有研究者提出，地球上曾存在一个RNA（核糖核酸）世界，这个世界出现在DNA和蛋白质诞生之前。
在这个世界中，DNA（脱氧核糖核酸）的近亲RNA（它可以被看作是一种酶，并且可以像蛋白质那样催化化学反应）无处不在。
我们现在要做的就是，找到一种方法，在加热的试管里面触发化学反应，验证上面提到的那些假说。
科学家已经取得了一些进展，他们的研究表明，一些化学物质可以自发排列，形成更加复杂的结构——例如氨基酸，还有众所周知的核苷酸（nucleotides，DNA的组成单元）。
2009年，现供职于英国医学研究委员会剑桥分子生物学实验室的约翰·萨瑟兰德（John Sutherland）所带领的团队已经证实，在“原始汤”中，确实可能存在自发的核苷酸合成过程。
[在2015年最新一期的《自然·化学》（Nature Chemistry）上，萨瑟兰德的团队报道，要生S）和紫外线（UV）就够了。
此成核酸前体，只需要氰化氢（HCN）、硫化氢（H2外，萨瑟兰还称，能生成核酸前体的反应条件也可以生成构成天然氨基酸和脂质的基本物质。
21世纪化学发展的四大难题
21世纪化学发展的四大难题化学是一门承上启下的中心科学；化学是一门与我们的衣、食、住、行都有密切联系、社会迫切需要的中心科学；化学是与信息、生命、材料、环境、能源、地球、空间和核科学等都有紧密联系、交叉和渗透的中心科学。
化学是20世纪发明的七大技术中排序第一的技术，21世纪的化学将在与物理学、生命科学、材料科学、信息科学、能源、环境、海洋、空间科学的相互交叉，相互渗透，相互促进中共同大发展。
然而，21世纪化学却面临着四大难题：一．建立精确有效而又普遍适用的化学反应的含时多体量子理论和统计理论化学反应理论和定律是化学的第一根本规律。
建立严格彻底的微观化学反应理论，既要从初始原理出发，又要巧妙地采取近似方法，使之能解决实际问题，包括决定某两个或几个分子之间能否发生化学反应?能否生成预期的分子?需要什么催化剂才能在温和条件下进行反应?如何在理论指导下控制化学反应?如何计算化学反应的速率?如何确定化学反应的途径等。
二．分子结构及其和性能的定量关系这里的“结构”包含构型、构象、手性、粒度、形状和形貌等，而“性能”则包含物理、化学和功能性质以及生物和生理活性等。
虽然从理论上证明一个分子的电子云密度可以决定它的所有性质，但实际计算困难很多，现在对结构和性能的定量关系的了解，还远远不够。
因而，大力发展密度泛函理论和其他计算方法，是21世纪化学的第二个重大难题。
三．生命现象中的化学机理问题充分认识和彻底了解人类和生物体内分子的运动规律。
例如：研究配体小分子和受体生物大分子相互作用的机理，这是药物设计的基础、光合作用的机理、生物固氮作用的机理、人类的大脑是用“泛分子”组装成的最精巧的计算机、蛋白质和DNA的理论研究等。
四．纳米尺度的基本规律当尺度在十分之几到10nm的量级，正处于量子尺度和经典尺度的模糊边界中，有许多新的奇异特性和新的效应，新的规律和重要应用，值得理论化学家去探索研究。
如：热力学性质与粒子尺度的关系、纳米粒子表面积引起性质的不同变化等。
化学十大难题
Scientific American：化学十大难题博主按：这是Scientific American科普杂志为国际化学年推出的专题。
化学一直声称自己是中心学科，是因为化学其实也就是分子科学，而无论物理还是生命科学，研究到最后，还是要在分子机制这个层面才能解决问题。
下面列出的化学十大难题，其实值得所有科学家关注，大家都能在这个舞台里一显身手，但是，化学家或许能在里面找到最好的切入点，从而找到解决问题的关键！1. How Did Life Begin? 生命从何而来?2. How Do Molecules Form? 分子如何形成?3. How Does the Environment Influence Our Genes? 环境如何影响人类基因?4. How Does the Brain Think and Form Memories? 大脑如何思考,并形成记忆?5. How Many Elements Exist? 到底存在多少种元素?6. Can Computers Be Made Out of Carbon? 我们能用碳元素制造出电脑吗?7. How Do We Tap More Solar Energy? 如何捕获更多太阳能?8 What Is the Best Way to Make Biofuels? 制造生物燃料的最佳途径是什么?9. Can We Devise New Ways to Create Drugs? 我们能研制出全新类型的药物吗?10. Can We Continuously Monitor Our Own Chemistry? 我们能实时监测自身的化学变化吗?CHEMISTRY：The 10 Unsolved MysteriesMany of the most profound scientific questions—and some of humanity’s most urgent problems—pertain to the science of atoms and moleculesBy Philip BallPhilip Ball has a Ph.D. in physics from the University of Bristol in England and was an editor at Nature for more than 20 years. He is the award-winning author of 15 books, including The Music Instinct: How Music Works, and Why We Can’t Do without It.1 How Did Life Begin?the moment when the first living beings arose from inanimate matter almost four billion years ago is still shrouded in mystery. How did relatively simple molecules in the primordial broth give rise to more and more complex compounds? And how did some of those compounds begin to process energy and replicate(two of the defining characteristics of life)? At the molecular level, all of those steps are, of course, chemical reactions,which makes the question of how life beganone of chemistry.The challenge for chemists is no longer to come up with vaguely plausible scenarios,of which there are plenty. For example, researchers have speculated about minerals such as clay acting as catalysts for the formation of the first self-replicating polymers(molecules that, like DNA or proteins, are long chains of smaller units); about chemical complexity fueled by the energy of deep-sea hydrothermal vents; and about an "RNA world," in which DNA’s cousin RNA—which can act as an enzyme and catalyze reactions the way proteins do—would have been a universal molecule, before DNA and proteins appeared. No, the game is to figure out how to test these ideas in reactions coddled in the test tube. Researchers have shown, for example, that certain relatively simple chemicals can spontaneously react to form the more complex building blocks of living systems, such as amino acids and nucleotides, the basic units of DNA and RNA. In 2009 a team led by John Sutherland, now at the MRC Laboratory of Molecular Biology in Cambridge, England, was able to demonstrate the formation of nucleotides from molecules likely to have existed in the primordial broth.Other researchers have focused on the ability of some RNA strands to act as enzymes,providing evidence in support of the RNA world hypothesis. Through such steps, scientists may progressively bridge the gap from inanimate matter to selfreplicating, self-sustaining systems. Now that scientists have a better view of strange and potentially fertile environments in our solar system—the occasional flows of water on Mars, the petrochemical seas of Saturn’s moon Titan, and the cold, salty oceans that seem to lurk under the ice of Jupiter’s moons Europa and Ganymede—the origin of terrestrial life seems only a part of grander questions: Under what circumstances can life arise? And how widely can its chemical basis vary? That issue is made richer still by the discovery, over the past 16 years, of more than 500 extrasolar planets orbiting other stars—worlds of bewildering variety.These discoveries have pushed chemists to broaden their imagination about the possible chemistries of life. For instance, NASA has long pursued the view that liquid water is a prerequisite, but now scientists are not so sure. How about liquid ammonia, formamide, an oily solvent like liquid methane or supercritical hydrogen on Jupiter? And why should life restrict itself to DNA, RNA and proteins? After all, severalartificial chemical systems have now been made that exhibit a kind of replication from the component parts without relying on nucleic acids. All you need, it seems, is a molecular system that can serve as a template for making a copy and then detach itself. Looking at life on Earth, says chemist Steven Benner of the Foundation for Applied Molecular Evolution in Gainesville,Fla.,―we have no way to decide whether the similarities [such as the use of DNA and proteins] reflect common ancestry or the needs of life universally.‖But if we retreat into saying that we have to stick with what we know, he says,―we have no fun.‖2 How Do Molecules Form?molecular structures may be a mainstay of high school science classes,but the familiar picture of balls and sticks representing atoms and the bonds among them is largely a conventional fiction.The trouble is that scientists disagree on what a more accurate representation of molecules should look like. In the 1920s physicists Walter Heitler and Fritz London showed how to describe a chemical bond using the equations of then nascent quantum theory, and the great American chemist Linus Pauling proposed that bonds form when the electron orbitals of different atoms overlap in space.A competing theory by Robert Mulliken and Friedrich Hund suggested that bonds are the result of atomic orbitals merging into―molecular orbitals‖that extend over more than one atom. Theoretical chemistry seemed about to become a branch of physics. Nearly 100 years later the molecularorbital picture has become the most common one, but there is still no consensus among chemists that it is always the best way to look at molecules. The reason is that this model of molecules and all others are based on simplifying assumptions and are thus approximate, partial descriptions. In reality, a molecule is a bunch of atomic nuclei in a cloud of electrons, with opposing electrostatic forces fighting a constant tug-of-war with one another, and all components constantly moving and reshuffling. Existing models of the molecule usually try to crystallize such a dynamic entity into a static one and may capture some of its salient properties but neglect others.Quantum theory is unable to supply a unique definition of chemical bonds that accords with the intuition of chemists whose daily business is to make and break them. There are now many ways of describing molecules as atoms joined by bonds. According to quantum chemist Dominik Marx of Ruhr University Bochum in Germany, pretty much all such descriptions―are useful in some cases but fail in others.‖Computer simulations can now calculate the structures and properties of molecules from quantum first principles with great accuracy—as long as the number of electrons is relatively small. ―Computational chemistry can be pushed to the level of utmost realism and complexity,‖Marx says. As a result, computer calculations can increasingly be regarded as a kind of virtual experiment that predicts the course of a reaction. Once the reaction to be simulated involves more than a few dozen electrons, however, the calculations quickly begin to overwhelm even the most powerful supercomputer, so the challenge will be to see whether the simulations can scaleup—whether, for example, complicated biomolecular processes in the cell or sophisticated materials can be modeled this way.3 How Does the Environment Influence Our Genes?the old idea of biology was that who you are is a matter of which genes you have. It is now clear that an equally important issue is which genes you use. Like all of biology, this issue has chemistry at its core. The cells of the early embryo can develop into any tissue type. But as the embryo grows, these so-called pluripotent stem cells differentiate, acquiring specific roles (such as blood, muscle or nerve cells) that remain fixed in their progeny. The formation of the human body is a matter of chemically modifying the stem cells’ chro mosomes in ways that alter the arrays of genes that are turned on and off. One of the revolutionary discoveries in research on cloning and stem cells, however, is that this modification is reversible and can be influenced by the body’s experiences. Cells d o not permanently disable genes during differentiation, retaining only those they need in a ―ready to work‖ state. Rather the genes that get switched off retain a latent ability to work—to give rise to the proteins they encode—and can be reactivated, for instance, by exposure to certain chemicals taken in from the environment.What is particularly exciting and challenging for chemists is that the control of gene activity seems to involve chemical events happening at size scales greater thanthose of atoms and molecules—at the so-called mesoscale—with large molecular groups and assemblies interacting. Chromatin, the mixture of DNA and proteins that makes up chromosomes, has a hierarchical structure. The double helix is wound around cylindrical particles made from proteins called histones, and this string of beads is then bundled up into higher-order structures that are poorly understood [see illustration on opposite page]. Cells exercise great control over this packing—how and where a gene is packed into chromatin may determine whether it is active or not.Cells have specialized enzymes for reshaping chromatin structure, and these enzymes have a central role in cell differentiation. Chromatin in embryonic stem cells seems to have a much looser, open structure: as some genes fall inactive, the chromatin becomes increasingly lumpy and organized. ―The chromatin seems to fix and maintain or stabilize the cells’ state,‖ says pathologist Bradley Bernstein of Massachusetts General Hospital. What is more, such chromatin sculpting is accompanied by chemical modification of both DNA and histones. Small molecules attached to them act as labels that tell the cellular machinery to silence genes or, conversely, free them for action. This labeling is called ―epigenetic‖ because it does not alter the information carried by the genes themselves.The question of the extent to which mature cells can be returned to pluripotency—whether they are as good as true stem cells, which is a vital issue for their use in regenerative medicine—seems to hinge largely on how far the epigenetic marking can be reset.It is now clear that beyond the genetic code that spells out many of the cells’ key instructions, cells speak in an entirely separate chemical language of genetics—that of epigenetics. ―People can have a genetic predisposition to many diseases, including cancer, but whether or not the disease manifests itself will often depend on environmental factors operating through these epigenetic pathways,‖ says geneticist Bryan Turner of the University of Birmingham in England.4 How Does the Brain Think and Form Memories?the brain is a chemical computer. Interactions between the neurons that form its circuitry are mediated by molecules: specifically, neurotransmitters that pass across the synapses, the contact points where one neural cell wires up to another. This chemistry of the mind is perhaps at its most impressive in the operation of memory, in which abstract principles and concepts—a telephone number, say, or an emotional association—are imprinted in states of the neural network by sustained chemical signals. How does chemistry create a memory that is both persistent and dynamic, as well as able to recall, revise and forget?We now know parts of the answer. A cascade of biochemical processes, leading to a change in the amounts of neurotransmitter molecules in the synapse, triggers learning for habitual reflexes. But even this simple aspect of learning has short and long-term stages. Meanwhile more complex so-called declarative memory (of people, places, and so on) has a different mechanism and location in the brain, involving the activation of a protein called the NMDA receptor on certain neurons. Blocking thisreceptor with drugs prevents the retention of many types of declarative memory.Our everyday declarative memories are often encoded through a process called long-term potentiation, which involves NMDA receptors and is accompanied by an enlargement of the neuronal region that forms a synapse. As the synapse grows, so does the ―strength‖of its connection with neighbors—the voltage induced at the synaptic junction by arriving nerve impulses. The biochemistry of this process has been clarified in the past several years. It involves the formation of filaments within the neuron made from the protein actin—part of the basic scaffolding of the cell and the material that determines its size and shape. But that process can be undone during a short period before the change is consolidated if biochemical agents prevent the newly formed filaments from stabilizing. Once encoded, long-term memory for both simple and complex learning is actively maintained by switching on genes that give rise to particular proteins. It now appears that this process can involve a type of molecule called a prion. Prions are proteins that can switch between two different conformations. One of the conformations is soluble, whereas the other is insoluble and acts as a catalyst to switch other molecules like it to the insoluble state, leading these molecules to aggregate. Prions were first discovered for their role in neurodegenerative conditions such as mad cow disease, but prion mechanisms have now been found to have beneficial functions, too: the formation of a prion aggregate marks a particular synapse to retain a memory.There are still big gaps in the story of how memory works, many of which await filling with the chemical details. How, for example, is memory recalled once it has been stored? ―This is a deep problem whose analysis is just beginning,‖ says neuroscientist and Nobel laureate Eric Kandel of Columbia University.Coming to grips with the chemistry of memory offers the enticing and controversial prospect of pharmacological enhancement. Some memory-boosting substances are already known, including sex hormones and synthetic chemicals that act on receptors for nicotine, glutamate, serotonin and other neurotransmitters. In fact, according to neurobiologist Gary Lynch of the University of California, Irvine, the complex sequence of steps leading to long-term learning and memory means that there are many potential targets for such memory drugs.5 How Many Elements Exist?the periodic tables that adorn the walls of classrooms have to be constantly revised, because the number of elements keeps growing. Using particle accelerators to crash atomic nuclei together, scientists can create new ―superheavy‖ elements, which have more protons and neutrons in their nuclei than do the 92 or so elements found in nature. These engorged nuclei are not very stable—they decay radioactively, often within a tiny fraction of a second. But while they exist, the new synthetic elements such as seaborgium (element 106) and hassium (element 108) are like any other insofar as they have well-defined chemical properties. In dazzling experiments, researchers have investigated some of those properties in a handful of elusive seaborgium and hassium atoms during the brief instants before they fell apart.Such studies probe not just the physical but also the conceptual limits of the periodic table: Do superheavy elements continue to display the trends and regularities in chemical behavior that make the table periodic in the first place? The answer is thatsome do, and some do not. In particular, such massive nuclei hold on to the atoms’ innermost electrons so tightly that the electrons move at close to the speed of light. Then the effects of special relativity increase the electrons’ mass and may play havoc with the quantum energy states on which their chemistry—and thus the table’s periodicity—depends. Because nuclei are thought to be stabilized by particular ―magic numbers‖ of protons and neutrons, some researchers hope to find what they call the island of stability, a region a little beyond the current capabilities of element synthesis in which superheavies live longer. Yet is there any fundamental limit to their size? A simple calculation suggests that relativity prohibits electrons from being bound to nuclei of more than 137 protons.More sophisticated calculations defy that limit. ―The periodic system will not end at 137; in fact, it will never end,‖ insists nuclear physicist Walter Greiner of the Johann Wolfgang Goethe University Frankfurt in Germany. The experimental test of that claim remains a long way off.6 Can Computers Be Made Out of Carbon?computer chips made out of graphene—a web of carbon atoms—could potentially be faster and more powerful than silicon-based ones. The discovery of graphene garnered the 2010 Nobel Prize in Physics, but the success of this and other forms of carbon nanotechnol ogy might ultimately depend on chemists’ ability to create structures with atomic precision. The discovery of buckyballs—hollow, cagelike molecules made entirely of carbon atoms—in 1985 was the start of something literally much bigger. Six years later tubes of carbon atoms arranged in a chicken wire–shaped, hexagonal pattern like that in the carbon sheets of graphite made their debut. Being hollow, extremely strong and stiff, and electrically conducting, these carbon nanotubes promised applications ranging from high-strength carbon composites to tiny wires and electronic devices, miniature molecular capsules, and water-filtration membranes.For all their promise, carbon nanotubes have not resulted in a lot of commercial applications. For instance, researchers have not been able to solve the problem of how to connect tubes into complicated electronic circuits. More recently, graphite has moved to center stage because of the discovery that it can be separated into individual chicken wire–like sheets, called graphene, that could supply the fabric for ultraminiaturized, cheap and robust electronic circuitry. The hope is that the computer industry can use narrow ribbons and networks of graphene, made to measure with atomic precision, to build chips with better performance than silicon-based ones. “Graphene can be patterned so that the interconnect and placement problems of carbon nanotubes are overcome,‖ says carbon specialist Walt de Heer of the Georgia Institute of Technology. Methods such as etching, however, are too crude for patterning graphene circuits down to the single atom, de Heer points out, and as a result, he fears that graphene technology currently owes more to hype than hard science. Using the techniques of organic chemistry to build up graphene circuits from the bottom up—linking together“polyaromatic‖ molecules containing several hexagonal carbon rings, like little fragments of a graphene sheet—might be the key tosuch precise atomicscale engineering and thus to unlocking the future of graphene electronics.7 How Do We Tap More Solar Energy?with every sunrise comes a reminder that we currently tap only a pitiful fraction of the vast clean-energy resource that is the sun. The main problem is cost: the expense of conventional photovoltaic panels made of silicon still restricts their use. Yet life on Earth, almost all of which is ultimately solar-powered by photosynthesis, shows that solar cells do not have to be terribly efficient if, like leaves, they can be made abundantly and cheaply enough.“One of the holy grails of solar-energy research is using sunlight to produce fuels,‖ says Devens Gust of Arizona State University. The easiest way to make fuel from solar energy is to split water to produce hydrogen and oxygen gas. Nathan S. Lewis and his collaborators at Caltech are developing an artificial leaf that would do just that [see illustration on opposite page] using silicon nanowires.Earlier this year Daniel Nocera of the Massachusetts Institute of Technology and his co-workers unveiled a silicon-based membrane in which a cobalt-based photocatalyst does the water splitting. Nocera estimates that a gallon of water would provide enough fuel to power a home in developing countries for a day. ―Our goal is to make each home its own power station,‖ he says.Splitting water with catalysts is still tough. ―Cobalt catalysts such as the one that Nocera uses and newly discovered catalysts based on other common metals are promising,‖ Gust says, but no one has yet found an ideal inexpensive catalyst.“We don’t know h ow the natural photosynthetic catalyst, which is based on four manganese atoms and a calcium atom, works,‖ Gust adds.Gust and his colleagues have been looking into making molecular assemblies for artificial photosynthesis that more closely mimic their biological inspiration, and his team has managed to synthesize some of the elements that could go into such an assembly. Still, a lot more work is needed on this front. Organic molecules such as the ones nature uses tend to break down quickly. Whereas plants continually produce new proteins to replace broken ones, artificial leaves do not (yet) have the full chemical synthesis machinery of a living cell at their disposal.8 What Is the Best Way to Make Biofuels?instead of making fuels by capturing the rays of the sun, how about we let plants store the sun’s energy for us and then turn plant matter into fuels? Biofuels such as ethanol made from corn and biodiesel made from seeds have already found a place in the energy markets, but they threaten to displace food crops, particularly in developing countries where selling biofuels abroad can be more lucrative than feeding people at home. The numbers are daunting: meeting current oil demand would mean requisitioning huge areas of arable land.Turning food into energy, then, may not be the best approach. One answer could be to exploit other, less vital forms of biomass. The U.S. produces enough agricultural and forest residue to supply nearly a third of the annual consumption of gasoline and diesel for transportation. Converting this low-grade biomass into fuel requires breaking down hardy molecules such as lignin and cellulose, the main building blocks of plants. Chemists already know how to do that, but the existing methods tend to be too expensive, inefficient or difficult to scale up for the enormous quantities of fuel that the economy needs.One of the challenges of breaking down lignin—cracking open the carbon-oxygen bonds that link ―aromatic,‖ or benzenetype, rings of carbon atoms—was recently met by John Hartwig and Alexey Sergeev, both at the Universityof Illinois. They found a nickel-based catalyst able to do it. Hartwig points out that ifbiomass is to supply nonfossil-fuel chemical feedstocks as well as fuels, chemists will also need to extract aromatic compounds (those having a backbone of aromatic rings) from it. Lignin is the only major potential source of such aromatics in biomass.To be practical, such conversion of biomass will, moreover, need to work with mostly solid biomass and convert it into liquid fuels for easy transportation along pipelines. Liquefaction would need to happen on-site, where the plant is harvested. One of the difficulties for catalytic conversion is the extreme impurity of the raw material—classical chemical synthesis does not usually deal with messy materials such as wood. ―There’s no consensus on how all this will be done in the end,‖ Hartwig says. What is certain is that an awful lot of any solution lies with the chemistry, especially with finding the right catalysts. ―Almost e very industrial reaction on a large scale has a catalyst associated‖ with it, Hartwig points out.9 Can We Devise New Ways to Create Drugs?the core business of chemistry is a practical, creative one: making molecules, a key to creating everything from new materials to new antibiotics that can outstrip the rise of resistant bacteria. In the 1990s one big hope was combinatorial chemistry, in which thousands of new molecules are made by a random assembly of building blocks and then screened to identify those that do a job well. Once hailed as the future of medicinal chemistry, ―combi-chem‖ fell from favor because it produced little of any use.But combinatorial chemistry could enjoy a brighter second phase. It seems likely to work only if you can make a wide enough range of molecules and find good ways of picking out the minuscule amounts of successful ones. Biotechnology might help here—for example, each molecule could be linked to a DNA-based“bar code‖ that both identifies it and aids its extraction. Or researchers can progressively refine the library of candidate molecules by using a kind of Darwinian evolution in the test tube. They can encode potential protein-based drug molecules in DNA and then use error-prone replication to generate new variants of the successful ones, thereby finding improvements with each round of replication and selection. Other new techniques draw on nature’s mastery at uniting molecular fragments in prescribed arrangements. Proteins, for example, have a precise sequence of amino acids because that sequence is spelled out by the genes that encode the proteins. Using this model, future chemists might program molecules to assemble autonomously. The approach has the advantage of being ―green‖ in that it reduces the unwanted by-products typical of traditional chemical manufacturing and the associated waste of energy and materials.David Liu of Harvard University and his co-workers are pursuing this approach. They tagged the building blocks with short DNA strands that program the linker’s structure. They also created a molecule that walks along that DNA, reading its codes and sequentially attaching small molecules to the building block to make the linker—a process analogous to protein synthesis in cells. Liu’s method could be a handy way to tailor new drugs.“Many molecular life scientists believe that macromolecules will play an increasingly central, if not dominant, role in the future of therapeutics,‖ Liu says.10 Can We Continuously Monitor Our Own Chemistry?increasingly, chemists do not want to just make molecules but also to communicate with them: to make chemistry an information technology that will interface with anything from living cells to conventional computers and fiber-optic telecommunications.In part, it is an old idea: biosensors in which chemical reactions are used to report on concentrations of glucose in the blood date back to the 1960s, although only recently has their use for monitoring diabetes been cheap, portable and widespread. Chemical sensing could have countless applications—to detect contaminants in food and water at very low concentrations, for instance, or to monitor pollutants and trace gases present in the atmosphere. Faster, cheaper, more sensitive and more ubiquitous chemical sensing would yield progress in all of those areas.It is in biomedicine, though, that new kinds of chemical sensors would have the most dramatic potential. For instance, some of the products of cancer genes circulate in the bloodstream long before the condition becomes apparent to regular clinical tests. Detecting these chemicals early might make prognoses more timely and accurate. Rapid genomic profiling would enable drug regimens to be tailored to individual patients, thereby reducing risks of side effects and allowing some medicines to be used that today are hampered by their dangers to a genetic minority.Some chemists foresee continuous, unobtrusive monitoring of all manner of biochemical markers of health and disease, perhaps providing real-time information to surgeons during operations or to automated systems for delivering remedial drug treatments. This futuristic vision depends on developing chemical methods for selectively sensing particular substances and signaling about them even when the targets occur in only very low concentrations.MORE TO EXPLOREBeyond the Molecular Frontier: Challenges for Chemistry and Chemical Engineering. National Research Council. National Academies Press, 2003.Beyond the Bond. Philip Ball in Nature, Vol. 469, pages 26–28; January 6, 2011.Let’s Get Practical. George M. Whitesides and John Deutch in Nature, Vol. 469, pages 21–22; January 6, 2011.。
21世纪四大化学难题
21世纪的四大化学难题化学是与信息、生命、材料、环境、能源、地球、空间和核科学等八大新兴科学紧密联系、交叉和渗透的中心科学。
前不久在杭州召开的中国化学会创建70周年纪念大会上，北京大学化学学院教授、中国科学院院士徐光宪指出，21世纪是信息科学、合成化学和生命科学一路繁荣的世纪，同时化学也面临四大难题。
徐光宪说，化学的核心是合成化学，在20世纪的100年中，化学合成和分离了2285万种新物质、新药物、新材料、新分子以知足人类生活和高新技术进展的需要，没有哪一门其它科学能像化学那样，创造出如此众多的新物质，在合成化学领域共取得41项诺贝尔奖。
若是没有合成各类抗生素和大量新药物的技术，人类不能控制传染病和减缓心脑血管病，平均寿命要缩短25年；若是没有合成纤维、合成塑料、合成橡胶的技术，人类生活要受到专门大影响；信息技术的核心是集成电路芯片，是采用的化学制备的硅单晶片生产的，运算机的存储器等其它部件用了大量的化学合成材料；专门是若是没有哈勃发明的高压合成氨技术和以后的合成尿素技术，世界粮食产量至少要减半，哈勃也因此获诺贝尔奖。
尔后，C·博施改良了哈勃流程也获诺贝尔奖。
所以国别传媒把哈勃流程评为20世纪最重大的发明。
1.合成化学难题-化学反映理论成立严格完全的微观化学反映理论，是21世纪化学应该解决的第一个难题。
如何成立精准有效而又普遍适用的化学反映的含时多体量子理论和统计理论？化学是研究化学转变的科学，所以化学反映理论和定律是化学的第一根本规律。
应该说，目前的一些理论方式对描述复杂化学体系还有困难。
因此，成立严格完全的微观化学反映理论，既要从初始原理动身，又要巧妙地采取近似方式，使之能解决实际问题，包括决定某两个或几个分子之间可否发生化学反映？可否生成预期的分子？需要什么催化剂才能在温和条件下进行反映？如安在理论指导下控制化学反映？如何计算化学反映的速度？如何肯定化学反映的途径等，是21世纪化学应该解决的第一个难题。
化学四大难题
5.21世纪化学的四大难题（l）化学的第一根本规律（第一个世纪难题）：建立精确有效而又普遍适用的化学反应的含时多体量子理论和统计理论。
化学是研究化学变化的科学，所以化学反应理论和定律是化学的第一根本规律。
19世纪C．M．古尔德贝格和P．瓦格提出的质量作用定律，是最重要的化学定律之一，但它是经验的、宏观的定律。
H．艾林的绝对反应速度理论是建筑在过渡态、活化能和统计力学基础上的半经验理论。
过渡态、活化能和势能面等都是根据不含时间的薛定愕第一方程来计算的。
所谓反应途径是按照势能面的最低点来描绘的。
这一理论和提出的新概念虽然非常有用，但却是不彻底的半经验理论。
近年来发展了含时Hartree-Fock方法，含时密度泛函理论方法，以酉群相干态为基础的电子-原子核运动方程理论，波包动力学理论等。
但目前这些理论方法对描述复杂化学体系还有困难。
所以建立严格彻底的微观化学反应理论，既要从初始原理出发，又要巧妙地采取近似方法，使之能解决实际问题，包括决定某两个或几个分子之间能否发生化学反应？能否生成预期的分子？需要什么催化剂才能在温和条件下进行反应？如何在理论指导下控制化学反应？如何计算化学反应的速率？如何确定化学反应的途径？等等，是21世纪化学应该解决的第一个难题。
（2）化学的第二个世纪难题：分子结构及其和性能的定量关系。
这里“结构”和“性能”是广义的，前者包含构型、构象、手性、粒度、形状和形貌等，后者包含物理、化学和功能性质以及生物和生理活性等。
虽然W．Kohn从理论上证明一个分子的电子云密度可以决定它的所有性质，但实际计算困难很多，现在对结构和性能的定量关系的了解，还远远不够。
要大力发展密度泛函理论和其他计算方法。
这是21世纪化学的第二个重大难题。
例如：①如何设计合成具有人们期望的某种性能的材料？②如何使宏观材料达到微观化学键的强度？例如“金属胡须”的抗拉强度比通常的金属丝大一个数量级，但还远未达到金属-金属键的强度，所以增加金属材料强度的潜力是很大的。
分析化学前沿领域
一、分析化学的发展现状
近代分析化学: 物质的定性和定量
现代分析化学: 创立和应用各种方法、仪器和策略
以获得在时间和空间内有关物质的组成、 结构、形态等全面信息。
一、分析化学的发展现状
? 分析化学的研究应用范围 现代分析化学融合许多学科的新成果, 形成了许多当代非常活跃 的研究应用领域:
1、生命科学中的分析化学
? 需要解决的分析化学问题
6）化学生物学及其相关问题: 药物作用靶点的识别；组 合化学药物合成的筛选；高通量的药物分析化学
7) 中草药有效成分分析—指纹图谱 8) 滥用药物的监控及分析 ……
THE SMALL-MOLECULE APPROACH TO BIOLOGY
1、生命科学中的分析化学
2）蛋白组学:
小分子与蛋白质、核酸等大分子作用引起其 构象的变化并影响其功能, 糖一蛋白化合物 结构多样性如何决定其功能的多样性, 真核 细胞周期调控中的蛋白质磷酸化作用等。
1、生命科学中的分析化学
? 需要解决的分析化学问题
3）单分子、单细胞分析以及实时活体分析 4) 生命体系复杂过程中的分析化学研究 5）重大疾病的预警与快速检测 (SARS、甲型H1N1流感)
分析化学前沿领域
一、分析化学的发展现状 二、分析化学的发展趋势 三、当今分析科学的前沿领域
一、分析化学的发展现状
? 分析化学的发展 分析化学经历了三次重大变革。
分析末－20世纪30年代 溶液化学分析
20世纪30年代－70年代 仪器分析/物理方法
现代 分析化学
? 化学既是传统自然科学中承上启下的中心科学, 也是与信息、生命、 材料、环境、能源、地球、空间和核科学等 8大朝阳科学都有紧密联 系、交叉、渗透的中心科学。
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21世纪四大化学难题
到了21世纪，数学界、物理学界和生物学界都相继提出了各自领域的重大难题或奋斗目标。
但在化学界，一直没有人明确提出哪些是化学要解决的世纪难题。
近年来，在世界范围内出现了淡化化学的思潮。
那么化学界果真提不出重大难题吗？有人对这一问题，提出21世纪的四大化学难题供大家一起探讨。
如何建立精确有效而又普遍适用的化学反应的含时多体量子理论和统计理论？
化学是研究化学变化的科学，所以化学反应理论和定律是化学的第一根本规律。
应该说，目前的一些理论方法对描述复杂化学体系还有困难。
因此，建立严格彻底的微观化学反应理论，既要从初始原理出发，又要巧妙地采取近似方法，使之能解决实际问题，包括决定某两个或几个分子之间能否发生化学反应？能否生成预期的分子？需要什么催化剂才能在温和条件下进行反应？如何在理论指导下控制化学反应？
如何计算化学反应的速率？如何确定化学反应的途径等，是21世纪化学应该解决的第一个难题。
对于这一世纪难题，应予首先研究的课题有：(1)充分了解若干个重要的典型的化学反应的机理，以便设计最好的催化剂，实现在最温和的条件进行反应，控制反应的方向和手性，发现新的反应类型，新的反应试剂。
(2)在搞清楚光合作用和生物固氮机理的基础上，设计催化剂和反应途径，以便打断CO2, N2等稳定分子中的惰性化学键。
(3)研究其它各种酶催化反应的机理。
酶对化学反应的加速可达100亿倍，专一性达100%。
如何模拟天然酶，制造人工催化剂，是化学家面临的重大难题。
(4)充分了解分子的电子、振动、转动能级，用特定频率的光脉冲来打断选定的化学键——选键化学的理论和实验技术。
如何确立结构和性能的定量关系？这里“结构”和“性能”是广义的，前者包含构型、构象、手性、粒度、形状和形貌等，后者包含物理、化学和功能性质以及生物和生理活性等。
这是21世纪化学的第二个重大理论难题。
要优先研究的课题有：(1)分子和分子间的非共价键的相互作用的本质和规律。
(2)超分子结构的类型，生成和调控的规律。
(3)给体-受体作用原理。
(4)进一步完善原子价和化学键理论，特别是无机化学中的共价问题。
(5)生物大分子的一级结构如何决定高级结构？高级结构又如何决定生物和生理活性？(6)分子自由基的稳定性和结构的关系。
(7)掺杂晶体的结构和性能的关系。
(8)各种维数的空腔结构和复杂分子体系的构筑原理和规律。
(9)如何设计合成具有人们期望的某种性能的材料？(10)如何使宏观材料达到微观化学键的强度？例如“金属胡须”的抗拉强度比通常的金属丝大一个量级，但还远未达到金属-金属键的强度，所以增加金属材料强度的潜力是很大的。
以上各方面是化学的第二根本问题，其迫切性可能比第一问题更大，因为它是解决分子设计和实用问题的关键。
如何揭示生命现象的化学机理？充分认识和彻底了解人类和生物的生命运动的化学机理，无疑是21世纪化学亟待解决的重大难题之一。
例如：(1)研究配体小分子和受体生物大分子相互作用的机理，这是药物设计的基础。
(2)化学遗传学为哈佛大学化学教授Schreiber所创建。
他的小组合成某些小分子，使之与蛋白质结合，并改变蛋白质的功能，例如使某些蛋白酶的功能关闭。
这些方法使得研究者们不通过改变产生某一蛋白质的基因密码就可以研究它们的功能，为开创化学蛋白质组学，化学基因组学(与生物学家以改变基因密码来研究的方法不
同)奠定基础。
(3)搞清楚光合作用、生物固氮作用，以及牛、羊等食草动物胃内酶分子如何把植物纤维分解为小分子的反应机理，为充分利用自然界丰富的植物纤维资源打下基础。
(4)人类的大脑是用“泛分子”组装成的最精巧的计算机。
如何彻底了解大脑的结构和功能将是21世纪的脑科学、生物学、化学、物理学、信息和认知科学等交叉学科共同来解决的难题。
(5)了解活体内信息分子的运动规律和生理调控的化学机理。
(6)了解从化学进化到手性和生命起源的飞跃过程。
(7)如何实现从生物分子(biomolecules)到分子生命(molecular life)的飞跃？如何制造活的分子(Make life)，跨越从化学进化到生物进化的鸿沟。
(8)研究复杂、开放、非平衡的生命系统的热力学，耗散和混沌状态，分形现象等非线形科学问题。
如何揭示纳米尺度的基本规律?纳米分子和材料的结构与性能关系的基本规律是21世纪的化学和物理需要解决的重大难题之一。
现在中美日等国都把纳米科学技术定为优先发展的国家目标。
钱学森先生说，继信息科学之后，纳米科学技术可能引起新一轮的产业革命。
在复杂性科学和物质多样性研究中，尺度效应至关重要。
尺度的不同，常常引起主要相互作用力的不同，导致物质性能及其运动规律和原理的质的区别。
纳米尺度体系的热力学性质，包括相变和“集体现象”如铁磁性，铁电性，超导性和熔点等与粒子尺度有重要的关系。
当尺度在十分之几到10纳米的量级，正处于量子尺度和经典尺度的模糊边界中，此时热运动的涨落和布朗运动将起重要的作用。
例如金的熔点为1063℃，纳米金(5-10nm)的融化温度却降至330℃。
银的熔点为960.3℃，而纳米银(5-10nm)为100℃。
四大难题破解后的美好前景
经过50-100年的努力，如果解决了我这里提出的化学四大难题，不难设想我们美好的远景：(1)在解决第一和第三难题，充分了解光合作用、固氮作用机理和催化理论的基础上，我们可以期望实现农业的工业化，在工厂中生产粮食和蛋白质，大大缩减宝贵的耕地面积，使地球能养活人口的数目成倍增加。
(2)在解决第二和第四难题的基础上，我们可以期望得到比现在性能最好的合金钢材强度大十倍，但重量轻几倍的合成材料，使城市建筑和桥梁建设的面貌完全更新。
(3)在充分了解结构与性能关系的基础上，我们能合成出高效、稳定、廉价的太阳能光电转化材料，组装成器件。
太阳投射到地球上的能量，是当前全世界能耗的一万倍。
如果光电转化效率为10%，我们只要利用0.1%的太阳能，就能满足当前全世界能源的需要。
(4)未来的化工企业将是绿色的，零排放的，原子经济的，物质在内部循环的企业。
(5)在合成了廉价的可再生的储氢材料和能转换材料的基础上，街上行走的汽车将全部是零排放的电动汽车。
我们穿的将是空调衣服。
(6)海水淡化将成为重要工业，从而解决人类生存最严重的挑战----淡水资源
紧缺问题。