对液体表面张力的微观解释的几点商榷

1 在液态中,在某种情况下,当温度一定时可认为分子处于静态平衡位置。本文认为,表面张力是由液体表面层分子受到一个指向液内的合力所引起的以及表面张力是由液体表面层分子受到一个指向液内的合引力所引起的提法都不完善。 2 本文论证了在表面层分子从各个方面所受的斥力不相同,从而提出了表面层分子所受的斥应力不具有各相同性的假定。 3 本文从暂态过程作出了分子从表面层下方移到上方时的受力分析,并依托正势能与负势能的变化,从力和能的角度来说明液面具有附加势能(自由能),从而分析了液体的表面现象。 4 根据排列规则,并充分考虑到了斥力作用,以水为例作了粗略计算,从而得出液体表面层切向上的相互作用的合引力大于相互作用的合斥力,说明了表面张力在宏观上是一对沿切向上的相互作用的引力。综上所述,在解释表面张力的微观机制时,不应该忽略斥力作用。

Discussion on Some Disputable Views about Micromechanism of Surface Tenson of Liquid

In liquids, at certain circumstances, as in a given temperture, the molecule of the liquid is considered as under a condition of static equilibrium. Some authors consider that each molecle of surface layer is accepted by a resultant force which directs toward the bulk of the liquid, and some others hold that each molecule in this layer is accepted by a composite attractive force which directs toward the bulk of the liquid. The writer of this paper thinks that both of these views are not complete. In this paper, the writer supposes that the repulsive force acting upon each molecule in the surface layer is not identical, so as to conclude and propose a hypothesis that each molecule of liquid accepting the repulsive stress does not possess isotropy. This paper explains that the essence which originate the induction of surface tension involves two factors: one, the molecular movement in this layer from lower to upper part (i. e. transient state process), relating on mechanical analysis; the other, the changing of positive and negative potential energy. From the above both points, each molecule in this layer contains surplus potential (free) energy in comparision with the bulk of the liquid. According to the arrangement rules, the action of repulsive force of molecules in this layer should be fully considered. Using water for example, by rough calculation, the surface tension is approved macroscopically to be a couple of the attractive force of interaction along a tangent to surface layer. The conclusion of the above discussion is that while analysing micromechanism of surface tension, we should fully consider the action of repulsive force.