Activity Coefficient Formula:
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Definition: The activity coefficient (γ) is a factor used in thermodynamics to account for deviations from ideal behavior in a mixture of chemical substances.
Purpose: It helps quantify how the behavior of real solutions differs from ideal solutions in vapor-liquid equilibrium calculations.
The calculator uses the formula:
Where:
Explanation: The formula relates the activity coefficient to measurable thermodynamic properties through the K-value expression.
Details: Accurate activity coefficients are crucial for designing separation processes, predicting phase behavior, and modeling chemical equilibrium in non-ideal systems.
Tips: Enter the K-value, fugacity coefficient, total system pressure, and saturation pressure. All values must be positive numbers.
Q1: What does an activity coefficient of 1 mean?
A: An activity coefficient of 1 indicates ideal solution behavior where Raoult's Law applies exactly.
Q2: When would activity coefficients deviate significantly from 1?
A: Significant deviations occur in systems with strong molecular interactions (hydrogen bonding, polarity) or size differences between components.
Q3: How is the K-value determined experimentally?
A: K-values are typically determined from vapor-liquid equilibrium measurements at known temperatures and pressures.
Q4: What's the difference between fugacity and activity coefficients?
A: Fugacity coefficients correct for non-ideal gas behavior, while activity coefficients correct for non-ideal liquid behavior.
Q5: Can this calculator be used for multicomponent systems?
A: This calculates γ for one component at a time. For mixtures, you would need to calculate γ for each component separately.