Residual Enthalpy Formula:
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Definition: Residual enthalpy is the difference between the actual enthalpy of a substance and its enthalpy in the ideal gas state at the same temperature.
Purpose: It measures the deviation from ideal gas behavior and is important in thermodynamic calculations for real gases and liquids.
The calculator uses the formula:
Where:
Explanation: The residual enthalpy is simply the actual enthalpy minus what the enthalpy would be if the substance behaved as an ideal gas.
Details: Residual enthalpy is crucial for accurate thermodynamic calculations in chemical engineering, particularly for processes involving real gases and phase changes.
Tips: Enter both enthalpy values in joules. The result will be the difference between them. Both values must be ≥ 0.
Q1: When is residual enthalpy significant?
A: It becomes important when dealing with real gases at high pressures or liquids, where deviations from ideal gas behavior are substantial.
Q2: Can residual enthalpy be negative?
A: Yes, residual enthalpy can be negative when the actual enthalpy is less than the ideal gas enthalpy.
Q3: How do I find the ideal gas enthalpy?
A: Ideal gas enthalpy can be calculated using heat capacity data and reference states, or from thermodynamic tables.
Q4: What units should I use?
A: The calculator uses joules (J) for all quantities. Convert other units to joules before calculation.
Q5: Does this account for temperature effects?
A: Temperature effects are included in the input enthalpy values, which should be at the same temperature.