Activity Coefficient Formula:
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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.
The calculator uses the formula:
Where:
Explanation: The formula relates the vapor-phase composition to the liquid-phase composition through the total pressure and saturation pressure.
Details: Accurate calculation of activity coefficients is crucial for designing distillation columns, predicting phase behavior, and modeling non-ideal mixtures in chemical processes.
Tips: Enter the mole fractions (between 0 and 1), total pressure, and saturation pressure (both in Pascals). All values must be > 0.
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).