What is the overall mass transfer coefficient and how is it related to individual coefficients?

The overall mass transfer coefficient (Kog or Kol) combines resistances in both phases for a two-film model. For gas absorption: 1/Kog = 1/kg + m/kl, where kg is gas-side coefficient, kl is liquid-side coefficient, and m is Henry's law constant slope. When m is small (highly soluble gas), gas-side resistance dominates; when m is large (sparingly soluble), liquid-side controls. This determines which phase resistance controls and where to focus process improvements.