Total Pressure Formula:
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Definition: This calculator determines the total pressure of a binary vapour system using Modified Raoult's Law, accounting for non-ideal behavior through activity coefficients.
Purpose: It's essential for dew-bubble point calculations in chemical engineering, particularly for vapor-liquid equilibrium (VLE) analysis of non-ideal mixtures.
The calculator uses the formula:
Where:
Explanation: The formula accounts for the non-ideal behavior of components through their activity coefficients, modifying Raoult's Law for more accurate calculations.
Details: Accurate pressure calculations are crucial for designing separation processes like distillation, predicting phase behavior, and ensuring proper operation of chemical processes.
Tips: Enter the mole fractions (must sum to 1), activity coefficients (typically >1 for positive deviation from ideality), and saturated pressures. All values must be positive.
Q1: What are typical values for activity coefficients?
A: For ideal mixtures, γ=1. For non-ideal mixtures, γ can range from 0.1 to 10 or more, depending on the system.
Q2: How do I obtain saturated vapor pressures?
A: Use Antoine equation or vapor pressure tables for pure components at the system temperature.
Q3: What if my mole fractions don't sum to 1?
A: The calculator will still compute, but results may not be physically meaningful. Ensure y₁ + y₂ = 1 for accurate results.
Q4: When is Modified Raoult's Law necessary?
A: When dealing with non-ideal mixtures where molecular interactions cause deviations from ideal behavior.
Q5: Can this be extended to multicomponent systems?
A: Yes, the principle can be extended, but the formula becomes more complex with additional terms for each component.