Critical Pressure

• Definition

  Critical Pressure is the pressure at critical point, where a pure substance is at the critical state (i.e., the singular point on the phase transition phenomenon of gas and liquid phase).

• Estimation Method

  - MolInstincts: The Property value is estimated by the combination of fundamental thermodynamic theories, modern modeling approaches, QSPR (quantitative structure-property relationships) methods, and ANN (Artificial Neural Network) with over fitting prevention algorithm, utilizing the quantum chemical calculations results and molecular descriptors. The estimated value is finally determined after manual inspection.
  - Joback: Group Contribution Method (Estimation of pure-component properties from group-contributions, Chem.Eng.Commun., 1987. 57. 233)
  - Gani: Group Contribution Method (New Group Contribution Method for Estimating Properties of Pure Compounds, AIChE J., 1994. 5. 1697)

• Supplementary Explanation on Accuracy

  Comment	Meaning of Comment
  ≤ 1%	0 ≤ abs%error ≤ 1
  ≤ 3%	1 < abs%error ≤ 3
  ≤ 5%	3 < abs%error ≤ 5
  ≤ 10%	5 < abs%error ≤ 10
  ≤ 20%	10 < abs%error ≤ 20
  ≤ 50%	20 < abs%error ≤ 50
  > 50%	abs%error > 50
  Exp. Data Unavailable	Experimental Data are Unavailable

  Where absolute % error means the absolute value of {(experimental value)-(calculated value)}/(experimental value).