C_l = X_tot/(F·K_D + 1−F); at F=0 ⇒ X_tot; at F=1 ⇒ X_tot/K_D

Sympy-exact witness of the two-phase Nernst mass-balance formula at its all-liquid and all-solid limits. Setup: C_l(F, K_D) = X_tot / (F·K_D + (1 − F)). Limits: F = 0 (all liquid) ⇒ denominator = 1, C_l = X_tot (no solid to sequester…