Boiling Point At Pressure Calculator

Boiling Point Equation:

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

Reference Temperature (T₀):

Enthalpy of Vaporization (ΔH_vap):

J/mol

Pressure (P):

Reference Pressure (P₀):

Boiling Point (T_b):

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1. What is the Boiling Point Equation?

The boiling point equation calculates the boiling temperature of a substance at a given pressure using the Clausius-Clapeyron relation. It accounts for how pressure affects the boiling point of liquids.

2. How Does the Calculator Work?

The calculator uses the boiling point equation:

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

Where:

\( T_b \) — Boiling point at pressure P (K)
\( T_0 \) — Reference boiling point (K)
\( R \) — Gas constant (8.314 J/mol·K)
\( \Delta H_{vap} \) — Enthalpy of vaporization (J/mol)
\( P \) — Pressure (Pa)
\( P_0 \) — Reference pressure (Pa)

Explanation: The equation shows how boiling temperature changes with pressure based on the thermodynamic properties of the substance.

3. Importance of Boiling Point Calculation

Details: Accurate boiling point calculation is crucial for chemical engineering processes, distillation design, pharmaceutical manufacturing, and understanding substance behavior under different pressure conditions.

4. Using the Calculator

Tips: Enter reference temperature in Kelvin, enthalpy of vaporization in J/mol, pressure and reference pressure in Pascals. All values must be positive and non-zero.

5. Frequently Asked Questions (FAQ)

Q1: Why does boiling point change with pressure?
A: Boiling occurs when vapor pressure equals atmospheric pressure. As external pressure decreases, less thermal energy is needed to reach boiling point.

Q2: What are typical enthalpy of vaporization values?
A: Water: ~40.7 kJ/mol, Ethanol: ~38.6 kJ/mol, Acetone: ~29.1 kJ/mol. Values vary by substance and temperature.

Q3: How accurate is this equation?
A: The equation provides good estimates for many liquids, but assumes constant enthalpy of vaporization and ideal gas behavior.

Q4: Can this be used for all pressures?
A: Best for moderate pressure ranges. At very high or very low pressures, more complex equations may be needed.

Q5: What's the reference pressure typically used?
A: Usually atmospheric pressure (101325 Pa or 1 atm) is used as the reference pressure P₀.