On the determinations of molecular fields - 1 From the variation of the viscosity of a gas with temperature
On the determinations of molecular fields - 1 From the variation of the viscosity of a gas with temperature
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DOI：
10.1098/rspa.1924.0081
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发表时间：
1924-10-01
期刊：
影响因子：
--
通讯作者：
Jones, JE
中科院分区：
文献类型：
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作者：
Jones, JE
< jats: p>在我们对原子和分子中电子的配置和运动有了更完整的认识之前，我们不能指望对气体中分子相遇时所产生的力的性质进行直接计算。确实，德拜最近在这个方向上迈出了一步，他研究了氢原子ourood中场的性质，假设氢原子ourood由围绕正核在圆形轨道上运动的负电荷组成，并展示了脉动场如何总体上产生排斥力，以及单位负电荷的吸引力。但很难看到这项工作如何扩展到更复杂的系统。目前，我们只能希望通过更间接的方法获得信息。其中一种方法是假定力的定律是确定的，然后用动力学理论的方法推导出气体粘度与温度的关系的适当定律。与实验上观察到的实际定律相比较，可以用来支持或否定假定的分子相互作用定律。不幸的是，应用分子动力学理论所涉及的计算是如此复杂，以致只在某些简单的情况下取得了进展。因此，麦克斯韦最初的研究只适用于分子排斥的逆五次方定律。他的工作已普遍化的查普曼和Enskog和formulaims已获得：粘滞系数的情况下（一）分子，这排斥根据逆< jats: italic>第n次幂定律，（二）分子的行为碰撞像钻机弹性领域和（三）分子的行为作为刚性弹性领域的弱吸引力的力量包围他们。在这些模型中，通常被称为萨瑟兰模型的LA被认为是理论与实验之间最好的一致性。但是，这种一致性决不是完美的。正如施密特、贝斯特尔迈耶、沃格尔和其他人所指出的，在低温下，与观测值有相当大的偏差。
< jats: p> Until our knowledge of the disposition and motion of the electrons in atoms and molecules is more complete, we cannot hope to make a direct calculation of the nature of the forces called into play during an encounter between molecules in a gas. It is true that a step in this direction has recently been made by Debye, who has investigated the nature of the field in the neighbourood of a hydrogen atom, assumed to consist of a negative charge in motion in circular orbit about a positive nucleus, and has shown how the pulsating eld gives rise on the whole to a force of repulsion, as well as one of attraction na unit negative charge. But it is difficult to see how this work can be extended to more complex systems. At present we can only hope to derive information by more indirect methods. One such method is to assume a definite law of force, and then by the methods of the kinetic theory to deduce the appropriate law of dependence of the viscosity of a gas on temperature. Comparison with the actual law, as observed experimentally, serves to support or discredit the assumed law of molecular interaction. Unfortunately, the calculations involved in the application of be kinetic theory are so complicated that progress has been made only in certain simple cases. Thus, the original investigation by Maxwell applied only to molecules repelling as the inverse fifth power law. His work has since be generalised by Chapman and Enskog and formulæ have been obtained: the coefficient of viscosity in the case of (i) molecules, which repel according an inverse< jats: italic> n th power law,(ii) molecules which behave on collision like rig elastic spheres and (iii) molecules which behave as rigid elastic spheres with weak attractive field of force surrounding them. Of these models the la generally referred to as Sutherland’s model, is found to give the best agreement between theory and experiment. But the agreement is by no means perfe As Schmidt, Bestelmeyer, Vogel, and others have pointed out, there considerable divergence from observed values at low temperatures.