Berthelot modified model

The Berthelot Modified Model calculator computes the pressure of a real gas from the knowledge of temperature, volume and pressure of the gas.

INSTRUCTIONS:  Choose units and enter the following:

• (T) This is the absolute temperature of the gas
• (T_c) This is the critical temperature specific to the gas
• (P_c) This is the critical pressure specific to the gas
• (P) This is the Absolute pressure of the gas
• (V_m) This is the molar volume of the gas

Pressure (P): The calculator returns the pressure of the gas in pascals (Pa).  However, this can be automatically converted to other pressure units via the pull-down menu.

Related Calculators

• Berthelot equation
• Berthelot modified model pressure of the gas
• gas constant R

The Math/Science

The formula for the modified Berthelot Model is:

     `P = (R * T)/V_m [ 1+(9*  P"/"P_c)/(128* T"/"T_c)(1-6/(T"/"T_c)^2)  ]`

where:

• P is the Berthelot modified model pressure of the gas
• R is the gas constant
• T is the absolute temperature of the gas
• T_c is the critical temperature specific to the gas
• P_c is the critical pressure specific to the gas
• P is the Absolute pressure of the gas
• V_m is the molar volume of the gas

The modified version the Berthelot model,  relating temperature, pressure, and volume of real gases, is more accurate than the Berthelot equation. It was modified by incorporating knowledge gained from empirical data gathered in analysis of real gases.