What are property routes in process simulation and how do you configure them correctly?

Property routes define which methods and models calculate each thermodynamic property. Configuration levels: equation of state selection (base method), transport property correlations (viscosity, thermal conductivity), reaction chemistry (equilibrium constants), and special handling (electrolytes, polymers). Consistency requirements: same EOS should calculate all equilibrium-related properties, reference states must match between enthalpy and Gibbs energy, and mixing rules should be consistent with phase equilibrium model. Common errors: mismatched activity coefficient and Henry's law models, inconsistent reference states causing energy balance errors, and using wrong method for property type (e.g., ideal gas Cp for liquid). Always validate property predictions against data.