纯物质固液平衡--压力对熔点的影响

Solid-Liquid Equilibrium of Pure Substances—Influence of Pressure on Melting Point

纯物质(即单组分体系)固液两相平衡时的温度即为该物质的熔点,本文分别Clapeyron方程和化学势两个角度讨论了压力对纯物质熔点的影响,得到相同的结果,即:对于液态摩尔体积大于固态摩尔体积的纯物质(大多数物质属此类),体系的压力增大时,其熔点升高;对于液态摩尔体积小于固态摩尔体积的纯物质(如水),体系的压力增大时,其熔点反而降低。

The temperature at which the pure substances(one-component system)achieve solid-liquid two-phase equilibrium is the melting point.In this paper,the influence of pressure on the melting point of pure substance was discussed based on Clapeyron equation and the chemical potential,respectively,and the same result was obtained:for pure substances with a molar volume of liquid-state larger than that of the solid-state(most substances are of this type),its melting point increases with the pressure;for pure substances(such as water)whose molar volume of liquid-state is smaller than that of the solid-state,its melting point decreases when the pressure increases.