Water Boiling Pressure Calculator

Clausius-Clapeyron Equation:

\[ P = P_0 \exp\left[ \frac{\Delta H_{vap}}{R} \left( \frac{1}{T_0} - \frac{1}{T_b} \right) \right] \]

Boiling Temperature (T_b):

Standard Pressure (P_0):

Enthalpy of Vaporization (ΔH_vap):

J/mol

Standard Boiling Temperature (T_0):

Calculated Pressure (P):

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1. What is the Clausius-Clapeyron Equation?

The Clausius-Clapeyron equation describes the relationship between vapor pressure and temperature for a substance. It's particularly useful for calculating the boiling pressure of water at different temperatures, providing insights into phase change behavior.

2. How Does the Calculator Work?

The calculator uses the Clausius-Clapeyron equation:

\[ P = P_0 \exp\left[ \frac{\Delta H_{vap}}{R} \left( \frac{1}{T_0} - \frac{1}{T_b} \right) \right] \]

Where:

\( P \) — Boiling pressure (Pa)
\( P_0 \) — Standard pressure (101325 Pa)
\( \Delta H_{vap} \) — Enthalpy of vaporization (40660 J/mol for water)
\( R \) — Gas constant (8.314 J/mol·K)
\( T_0 \) — Standard boiling temperature (373.15 K)
\( T_b \) — Boiling temperature (K)

Explanation: The equation calculates the pressure required for water to boil at a given temperature, based on thermodynamic principles of phase equilibrium.

3. Importance of Boiling Pressure Calculation

Details: Accurate boiling pressure calculations are essential for various applications including chemical engineering processes, meteorological studies, food processing, and high-altitude cooking adjustments.

4. Using the Calculator

Tips: Enter boiling temperature in Kelvin, standard pressure in Pascals, enthalpy of vaporization in J/mol, and standard boiling temperature in Kelvin. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: Why use Kelvin instead of Celsius?
A: The Clausius-Clapeyron equation requires absolute temperature values, making Kelvin the appropriate unit for thermodynamic calculations.

Q2: What is the standard enthalpy of vaporization for water?
A: At 100°C (373.15 K), the enthalpy of vaporization for water is approximately 40,660 J/mol.

Q3: How does altitude affect boiling pressure?
A: At higher altitudes, atmospheric pressure decreases, requiring lower temperatures for water to boil. This calculator helps determine the exact relationship.

Q4: Can this equation be used for other liquids?
A: Yes, but you need to use the appropriate enthalpy of vaporization and standard boiling point values for the specific liquid.

Q5: What are the limitations of this equation?
A: The equation assumes constant enthalpy of vaporization and ideal gas behavior, which may not hold perfectly over large temperature ranges.