理想气体绝热过程的认识误区∗

摘要

The marked feature of adiabatic processes is that there has volume-work exchange but no heat exchange between the system and the environments. The adiabatic processes of ideal gases are one of the difficulties of physical chemistry teaching, and the adiabatic irreversible processes have been a controversial issue. Two cognitive misunderstandings of adiabatic processes of ideal gases were discussed, and the essence of these two problems was analyzed. The adiabatic irreversible processes can take place indisputably, and the external pressures will change continuously ( expansion or compression under constant external pressures) . This work confirmed that an adiabatic process under constant external pressure was reasonable, but it was an irreversible process and Qp≠ΔH.%绝热过程的显著特征是系统与环境之间有功的交换，但没有热的交换。理想气体的绝热过程是物理化学课堂教学的难点之一，绝热不可逆过程也是一个争论颇多的问题。本文讨论了理想气体绝热恒外压过程认识的两个误区，并对这两个问题的实质进行了分析。本文认为绝热恒外压过程可以发生，且其压力也在不断变化中(恒外压膨胀或压缩)，但它是不可逆过程且Qp≠ΔH。