自发变化及其与不可逆过程关系的探讨

Discussion on Spontaneous Change and Its Relationship to Irreversible Process

现行物理化学教科书中虽有定义和解释自发变化,但对自发变化及自发判据的准确理解尚有争论。在现有文献讨论的基础上,本文尝试从平衡态的角度理解并定义自发变化,厘清自发判据与不可逆判据的关系。指出了判断系统变化是否自发的核心前提在于系统与环境之间处于平衡,而不是变化发生时环境是否对系统做功。并指出在该前提下,不可逆判据与自发判据是一致的,不可逆判据可以用于判断系统变化的自发性。最后探讨了常见判据的应用范围及其原因。可以看出,从平衡态角度理解自发变化能够反映自发变化的本质,也容易厘清不可逆判据与自发判据的关系,有助于准确把握自发变化及相关概念。

All textbooks of the physical chemistry define and explain the concept of the spontaneous change,but its exact meaning and especially the criteria for the spontaneous change are still controversial.Based on the discussion of literature,this paper proposes to interpret and define the spontaneous change from the perspective of the equilibrium state,and to clarify the relationship between the spontaneous change and the irreversible process.It is pointed out that the key prerequisite of defining the spontaneous change is the equilibrium between the system and the environment,not whether the environment does work to the system when the change occurs.Under this premise,the criteria for the irreversible process is consistent with the criteria for the spontaneous change.Finally,interpretation of common criteria in terms of the proposed definition is discussed.The discussion suggests that understanding the spontaneous change from the perspective of equilibrium can reflect its intrinsic nature,and it is also easy to clarify the relationship between irreversible criteria and spontaneous criteria,which is helpful to accurately understand the spontaneous change and related concepts.