Enthalpy using Integrated Form of Clausius-Clapeyron Equation Calculator

Formula Used:

\[ \Delta H = \frac{-\ln\left(\frac{P_f}{P_i}\right) \times [R]}{\left(\frac{1}{T_f} - \frac{1}{T_i}\right)} \]

Initial Pressure of System:

Final Pressure of System:

Initial Temperature:

Final Temperature:

Change in Enthalpy (J/kg):

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1. What is Enthalpy using Integrated Form of Clausius-Clapeyron Equation?

Definition: This calculator determines the change in enthalpy during a phase transition using pressure and temperature measurements.

Purpose: It's used in thermodynamics to calculate the heat content change during processes like vaporization or sublimation.

2. How Does the Calculator Work?

The calculator uses the integrated form of the Clausius-Clapeyron equation:

\[ \Delta H = \frac{-\ln\left(\frac{P_f}{P_i}\right) \times [R]}{\left(\frac{1}{T_f} - \frac{1}{T_i}\right)} \]

Where:

\( \Delta H \) — Change in enthalpy (J/kg)
\( P_i \) — Initial pressure (Pa)
\( P_f \) — Final pressure (Pa)
\( T_i \) — Initial temperature (K)
\( T_f \) — Final temperature (K)
\( R \) — Universal gas constant (8.314 J/mol·K)

Explanation: The natural log of the pressure ratio is multiplied by the gas constant and divided by the difference in reciprocal temperatures.

3. Importance of Enthalpy Calculation

Details: Enthalpy change calculations are crucial for designing heat exchangers, refrigeration systems, and understanding phase transitions.

4. Using the Calculator

Tips: Enter initial and final pressures in Pascals, and temperatures in Kelvin. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What units should I use for input?
A: Pressure must be in Pascals (Pa) and temperature in Kelvin (K) for accurate results.

Q2: When is this equation valid?
A: For phase transitions where the vapor phase behaves as an ideal gas and the molar volume of liquid is negligible.

Q3: What does a negative enthalpy change mean?
A: A negative value indicates an exothermic process (heat is released).

Q4: Can I use this for solid-liquid transitions?
A: No, this form is primarily for vapor-liquid or vapor-solid transitions.

Q5: Why use natural logarithm in the formula?
A: The ln function comes from integrating the differential form of the Clausius-Clapeyron equation.