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Activity Calculations

This section covers the theoretical foundations for activity calculations in particula, including the Binary Activity Thermodynamics (BAT) model and liquid-vapor partitioning. These concepts are essential for understanding how particula models organic aerosol thermodynamics and gas-particle equilibria.

Activity calculations determine how chemical species behave in mixtures, accounting for non-ideal interactions between molecules. In aerosol science, accurate activity models are critical for predicting:

  • Water uptake by organic aerosols
  • Phase separation in mixed organic-water systems
  • Gas-particle partitioning of semi-volatile compounds
  • Cloud droplet activation

Topics

  • Activity Theory

    Raoult's Law, activity coefficients, and the BAT model for non-ideal organic-water mixtures. Learn how particula calculates thermodynamic activities using AIOMFAC-derived fits.

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  • Equilibria Theory

    Liquid-vapor partitioning, phase separation, and equilibrium solving in aerosol systems. Understand how particula solves for gas-particle equilibrium concentrations.

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  • Examples: See the Equilibria How-To Guide for practical tutorials
  • API Reference: The particula.activity and particula.equilibria modules implement these concepts