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Definition: This calculator determines the total pressure in a vapor-liquid equilibrium (VLE) system using Modified Raoult's Law, which accounts for non-ideal behavior through activity coefficients.
Purpose: It helps chemical engineers and researchers calculate system pressures for distillation, absorption, and other separation processes.
The calculator uses the formula:
Where:
Explanation: The formula modifies Raoult's Law by incorporating an activity coefficient to account for deviations from ideal behavior in liquid mixtures.
Details: Accurate VLE calculations are crucial for designing separation processes, predicting phase behavior, and optimizing process conditions in chemical plants.
Tips: Enter all required parameters (mole fractions, activity coefficient, and saturated pressure). Mole fractions must be between 0 and 1. All values must be > 0.
Q1: When should I use Modified Raoult's Law instead of standard Raoult's Law?
A: Use Modified Raoult's Law when dealing with non-ideal liquid mixtures where activity coefficients significantly deviate from 1.
Q2: How do I determine the activity coefficient?
A: Activity coefficients can be determined experimentally or calculated using thermodynamic models like UNIQUAC or NRTL.
Q3: What units should I use for pressure?
A: The calculator uses Pascals (Pa), but you can convert from other units (1 atm = 101325 Pa).
Q4: Can I use this for multicomponent systems?
A: This calculator is for binary systems. For multicomponent systems, you would need to sum partial pressures of all components.
Q5: What if my vapor mole fraction is very small?
A: Be cautious with very small y values as they can lead to extremely high calculated pressures due to division by a small number.