Abstract: Acid-base equilibrium is a crucial topic in chemical education. However, current teaching practices only focus on describing acid-base dissociation and pH buffering in homogeneous solutions, without considering the influence of gas-phase components on acid-base dissociation and pH buffering in multiphase systems. To address this issue, this paper takes a typical aerosol multiphase system as an example and examines the impact of component volatility and hygroscopicity on the acid-base equilibrium in multiphase systems through the analysis of multiphase buffering theory and the effective dissociation constant pK_a^*. By doing so, it aims to stimulate students’ thinking and provide a new paradigm for teaching acid-base equilibrium in multiphase systems.

Key words: Multiphase buffer theory, Acid-base equilibrium, Effective dissociation constant