化学势外文翻译.doc

河北科技师范学院学士学位论文外文翻译 河北科技师范学院本科毕业论文外文翻译化学势院（系、部）名 称 ： 理化学院 专 业 名 称： 物理学 学 生 姓 名： 肖瑶 学 生 学 号： 1112080119 指 导 教 师： 郝爱民 2012年3月15日河北科技师范学院教务处制 郑州市中原区伏牛南路5号元70年代小区9-2-1103，雷景伟前为止，我们的讨论只局限于封闭的物理系统，即不能与周围环境进行物质交换的系统。现在我们把注意力转到这章的开放系统，这个系统中的物质不是封闭的。 假设在系统中引入dn摩尔质量的物质，加入的物质每千摩尔所含的内能很有可能在一个化学反应中被释放到该系统的其余部分。增加的能量正比于dn且可以写成.数量被称为化学势。一个带电极性分子受到库仑引力，当它被吸引到另一个分子的附近区域时，这种力量表现为负的势能，即“势阱”。 当新的粒子靠近它的邻居，它失去势能的同时获得动能。通过碰撞动能传递给其他粒子，使系统在此过程中获得内能。假设一个远离其它粒子无限远处的一个静止粒子，它的动能和势能全为零 。把该分子移动到第二个分子立场中，理论上，这可以被慢慢做以致动能可以被忽略不计，这个分子增加的动能大小等于势阱的深度，定量，中，是总的能量，为动能，为势能；为分子之间的距离。当，且时 ，所以图9.1 分子间作用力产生势阱的示意图 能量是守恒的，势能转化为动能，动能被添加到系统的内能中。 探求的大小是多少是合理的。在一个标准的实验室中实验，硫酸加入水中，导致了温度的上升。假设在室温下有千摩尔硫酸被加入到一升水中，我们确定出硫酸在水中的化学势。 相比于硫酸分子与水分子间的相互作用，我们可以假设硫酸分子间的相互作用是可以忽略的（所有的酸分子和水分子式呈现电极化的）水的比热容量是。因此水所获得的热量随增加的酸为 由于水的质量是酸的质量的倍，我们可忽略后者的比热容。化学势为每千摩尔 因为热量从酸转移到水转移，符号为负。 我们好奇每部分的化学势，即势阱深度的本质。由于一千摩尔拥有分子，这个值为焦或电子伏特（一电子伏特等于焦尔）大部分化学势为这个量级。 为了解释加入到系统中的量的影响我们需要添加一项到热力学基本方程中 （9.1） 在这里是加入的物质（每千摩尔中）的增量，为化学势每千摩尔焦耳。 如果在一个开放系统中且 （9.2）得到 （9.3） 也就是说，化学势被定义为恒定熵和体积下的每千摩尔的内能增量。 如果有多个种类的粒子被加入到系统中，则（9.1）式可写成 （9.4） （9.5） 表示除了保持不变的外的所有的集合， 另一种呈现与间的关系的为（9.4）式。这可以通过欧拉定理来求得齐次函数。欧拉定理表明，如果 （9.6）则 （9.7） 这个定理很容易地被差分方程所证明，设置（9.6）式的为1，现在假设所有种类物质的量，即所谓的成分在系统中增加了一倍或减半，推广来说，改变因子而不改变任何的基本状态的变量。然后广延量将随着产生改变，并且所有独立的广延量都将随因子的变化而变化。因此是适用于欧拉定理的齐次函数： （9.8）从的微分中我们知道， （9.9）把（9.9）式中的关系代入（9.8）式，我们得到 （9.10）我们已知吉布斯函数被定义为，立即可得 （9.11）如果只有一个组成部分存在，则或，在此种情形下就是每千摩尔单位的这种物质的吉布斯函数。最后我们采用差分方程（9.10），得到 （9.12）方程（9.4）和（9.12）等同，我们得到 （9.13）吉布斯-迪昂方程的一个关系式。差分方程（9.11）给出 （9.14）注意到。因此，如果我们让某个过程在恒定的温度和压强下发生，（9.13）式成立的前两项为零，所以和随之为零。随后，（9.14）式得到重要结论 （9.15）9.1 The chemical potential Until now we have confined our discussion to closed physical systems，which cannot exchange matter with their surroundings. We turn our attention in this chapter to open systems, in which the quantity of matter is not fixed. Supposed that dn kilomoles of matter are introduced into a system. Each kilomole of added matter has its own internal energy that is released to the rest of the system, possibly in a chemical reaction . the added energy is proportional to dn and may be written as . The quantity is called the chemical potential. The chemical potential is associated with intermolecular forces. An electrically polarized molecule experiences a coulomb attraction when it is brought into the vicinity of another such molecule,*this force is expressed as a negative potential energy, a sort of “potential well.” As the new particle approaches its neighbor, it gains kinetic energy while losing potential energy. The kinetic energy is imparted to other particles through collisions, so the system gains internal energy in the process. Consider a motionless motionless molecule infinitely distant from other molecules. Its kinetic energy and potential energy are both zero. The molecule is moved into the force field of a second molecule. This can , in principle, be done slowly so that the kinetic energy is negligibly small. Left by itself, however, the molecule picks up kinetic energy in magnitude to the depth of potential well(figure9.1)quantitatively, Where E is the totle energy, K is the kinetic energr, and is the potential energy; is the distance between the molecule and its neighbor, at ,and so everywhere. At , so Figure 9.1 Schematic diagram of a potential well due to intermolecular forces. Energy is conserved, but a conversion from potential energy to kinetic energy takes place. The kinetic energy is added to the internal energy of the system.It is reasonable to ask what the magnitude of is. In a standard laboratory experiment, sulfuric acid is added to water , producing an increase in temperature. Imagine that kilomoles of acid at room temperature are added to a liter of water , also at room temperature. the temperature is observed to rise . we wish to determine the chemical potential of acid in water. We shall assume that the interaction among the acid molecules is small compared with their interaction with the water molecules (both acid and water molecules are electrically polarized.) the specific heat capacity of water is . thus the heat gained by the water through the addition of the acid is Since the mass of the water is more than times the mass of the acid, we can ignore the heat capacity of the latter. The chemical potential then ,is The sign is negative because heat is transferred from the acid to the water. We are interested in the chemical energy per particle, which is essentially the depth of the potential well. Since a kilomole has molecules, this value is J or (one electron volt is equal to joules.) most chemical potentials are of this order of magnitude. To account for the effect of adding mass to a system, we need to add a term to our fundamental equation of thermodynamics: (9.1)Here dn is the increment of mass added (in kilomoles) and is the chemical potential in joules per kilomole. If, in an open systkem, and (9.2)Then (9.3) That is, the chemical potential is defined as the internal energy per kilomole added under conditions of constant entropy and volume. If there is more than one type of particle added to the system (say mtypes), then Equation(9.1)becomes , (9.4)With (9.5) The subscript means that all other except are held constant.Another way of seeing the relationship between and is integrate Equation (9.4).This can be done by using Eulers theorem for homogenous functions. Eulers theorem states that if , (9.6)Then (9.7) The theorem can be easily proved by differentiating equation (9.6) with respect to and then setting equal to unity. Now . Suppose the amounts of all the types of substance, called constituents, in the system were doubled or halved or, more generally, changed by the factor without changing any of the fundamental state variables. then the extensive variable would be changed by and all the independent, extensive state variables would also be changed by the factor .thus is a homogeneous function and Eulers theorem can be applied to it: (9.8) From the differential of we know that , , (9.9) Substituting the relations of Equation (9.9) in the Equation(9.8),w