Water Boiling Point Under Vacuum Calculator

Boiling Point Equation:

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

Boiling Point (T_b):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Water Boiling Point Under Vacuum Equation?

The equation calculates the boiling point of water under reduced pressure conditions using the Clausius-Clapeyron relation. It shows how boiling temperature decreases as pressure decreases, which is crucial in various industrial and laboratory processes.

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 under vacuum (K)
\( T_0 \) — Standard boiling point (373.15 K)
\( R \) — Gas constant (8.314 J/mol·K)
\( \Delta H_{vap} \) — Enthalpy of vaporization (J/mol)
\( P \) — Vacuum pressure (Pa)
\( P_0 \) — Standard pressure (101325 Pa)

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

3. Importance of Boiling Point Calculation

Details: Accurate boiling point calculation under vacuum is essential for processes like vacuum distillation, evaporation, and concentration where temperature-sensitive materials need to be processed at lower temperatures to prevent degradation.

4. Using the Calculator

Tips: Enter vacuum pressure in Pascals (Pa) and enthalpy of vaporization in J/mol. The default enthalpy value is set to 40600 J/mol for water at 100°C. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: Why does boiling point decrease under vacuum?
A: Reduced pressure lowers the energy required for liquid molecules to escape into the vapor phase, thus lowering the boiling temperature.

Q2: What is the typical enthalpy of vaporization for water?
A: For water at 100°C, the enthalpy of vaporization is approximately 40600 J/mol, though it varies slightly with temperature.

Q3: What units should I use for pressure?
A: The calculator uses Pascals (Pa). 1 atm = 101325 Pa, 1 bar = 100000 Pa, 1 mmHg = 133.322 Pa.

Q4: Can this equation be used for other liquids?
A: Yes, but you need to use the appropriate values for T₀, P₀, and ΔH_vap specific to that liquid.

Q5: What are some practical applications?
A: Pharmaceutical processing, food concentration, chemical distillation, and any process where reducing boiling temperature prevents thermal degradation.