Activity Coefficient using Modified Raoult's Law in VLE Calculator

Activity Coefficient Formula:

\[ \gamma_{Raoults} = \frac{y_{Gas} \times P_T}{x_{Liquid} \times P_{sat}} \]

Mole Fraction in Vapor Phase (yGas):

Total Pressure (PT):

Mole Fraction in Liquid Phase (xLiquid):

Saturated Pressure (Psat):

Activity Coefficient (γRaoults):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Activity Coefficient in Raoult's Law?

Definition: The Activity Coefficient in Raoult's Law is a factor used in thermodynamics to account for deviations from ideal behavior in a mixture of chemical substances.

Purpose: It helps quantify how much a component in a liquid mixture deviates from ideal behavior when calculating vapor-liquid equilibrium.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \gamma_{Raoults} = \frac{y_{Gas} \times P_T}{x_{Liquid} \times P_{sat}} \]

Where:

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

Explanation: The formula relates the vapor-phase composition to the liquid-phase composition through the total pressure and saturation pressure.

3. Importance of Activity Coefficient

Details: Accurate calculation of activity coefficients is crucial for designing distillation columns, predicting phase behavior, and modeling non-ideal mixtures in chemical processes.

4. Using the Calculator

Tips: Enter the mole fractions (between 0 and 1), total pressure, and saturation pressure (both in Pascals). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What does an activity coefficient of 1 mean?
A: A value of 1 indicates ideal behavior where Raoult's Law applies perfectly.

Q2: What range of values can the activity coefficient have?
A: Typically between 0 and 10, though extreme non-ideal systems may fall outside this range.

Q3: When would I need to calculate activity coefficients?
A: For vapor-liquid equilibrium calculations, especially when dealing with non-ideal mixtures in distillation or absorption processes.

Q4: How do I find saturation pressure?
A: From experimental data, vapor pressure correlations like Antoine equation, or thermodynamic tables.

Q5: What units should I use for pressure?
A: The calculator uses Pascals (Pa), but you can convert from other units (1 atm = 101325 Pa).