Total Pressure using Modified Raoult's Law in VLE Calculator

Formula Used:

\[ P_T = \frac{x_{liquid} \times \gamma_{Raoults} \times P_{sat}}{y_{gas}} \]

Mole Fraction in Liquid Phase:

Activity Coefficient:

Saturated Pressure:

Mole Fraction in Vapor Phase:

Total Pressure (Pa):

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1. What is Total Pressure using Modified Raoult's Law?

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.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ P_T = \frac{x_{liquid} \times \gamma_{Raoults} \times P_{sat}}{y_{gas}} \]

Where:

\( P_T \) — Total pressure of gas (Pa)
\( x_{liquid} \) — Mole fraction in liquid phase
\( \gamma_{Raoults} \) — Activity coefficient
\( P_{sat} \) — Saturated pressure (Pa)
\( y_{gas} \) — Mole fraction in vapor phase

Explanation: The formula modifies Raoult's Law by incorporating an activity coefficient to account for deviations from ideal behavior in liquid mixtures.

3. Importance of VLE Calculations

Details: Accurate VLE calculations are crucial for designing separation processes, predicting phase behavior, and optimizing process conditions in chemical plants.

4. Using the Calculator

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.

5. Frequently Asked Questions (FAQ)

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.