Water Boiling Point At Different Pressures Calculator

Water 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):

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1. What is the Water Boiling Point Equation?

The water boiling point equation calculates how the boiling temperature of water changes with pressure. It's based on the Clausius-Clapeyron relation and is important for various scientific and engineering applications.

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)
\( T_0 \) — Standard boiling point (373.15 K)
\( R \) — Gas constant (8.314 J/mol·K)
\( \Delta H_{vap} \) — Enthalpy of vaporization (40650 J/mol)
\( P \) — Pressure (Pa)
\( P_0 \) — Standard pressure (101325 Pa)

Explanation: The equation shows how boiling point decreases with decreasing pressure and increases with increasing pressure.

3. Importance of Boiling Point Calculation

Details: Understanding how pressure affects boiling point is crucial for applications in high-altitude cooking, industrial processes, chemical engineering, and meteorological studies.

4. Using the Calculator

Tips: Enter pressure in Pascals (Pa). The calculator will output the boiling point in both Kelvin and Celsius. Pressure must be greater than 0.

5. Frequently Asked Questions (FAQ)

Q1: Why does boiling point change with pressure?
A: Boiling occurs when vapor pressure equals atmospheric pressure. At lower pressures, less energy is needed for vaporization, so boiling occurs at lower temperatures.

Q2: What is the boiling point at high altitudes?
A: At high altitudes where pressure is lower, water boils at temperatures below 100°C. For example, at 3000m altitude, water boils at about 90°C.

Q3: Can water boil at room temperature?
A: Yes, if pressure is reduced sufficiently. At about 0.03 atm pressure, water boils at room temperature (25°C).

Q4: What are the limitations of this equation?
A: The equation assumes constant enthalpy of vaporization, which is not strictly true over large temperature ranges. It's most accurate for moderate pressure changes.

Q5: How does this affect cooking times?
A: At higher altitudes where boiling point is lower, foods take longer to cook because the maximum cooking temperature is reduced.