Boiling Point Calculator

Boiling Point Formula:

\[ T = \frac{\Delta H_{vap}}{\Delta S_{vap}} \]

Boiling Point (K):

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1. What is a Boiling Point Calculator?

Definition: This calculator estimates the boiling point of a substance using its enthalpy and entropy of vaporization.

Purpose: It helps chemists and students understand and predict boiling points based on thermodynamic properties.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ T = \frac{\Delta H_{vap}}{\Delta S_{vap}} \]

Where:

\( T \) — Boiling point (Kelvin)
\( \Delta H_{vap} \) — Enthalpy of vaporization (J/mol)
\( \Delta S_{vap} \) — Entropy of vaporization (J/mol·K)

Explanation: The boiling point occurs when the liquid and gas phases are in equilibrium, where the Gibbs free energy change is zero.

3. Importance of Boiling Point Calculation

Details: Accurate boiling point prediction is crucial for chemical processes, material selection, and safety considerations in industrial applications.

4. Using the Calculator

Tips: Enter the enthalpy of vaporization (ΔH_vap) in J/mol and entropy of vaporization (ΔS_vap) in J/mol·K (default 88 J/mol·K, typical for many liquids). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is entropy of vaporization often around 88 J/mol·K?
A: This is known as Trouton's rule - many liquids have ΔS_vap ≈ 88 J/mol·K at their boiling points.

Q2: How accurate is this calculation?
A: It provides a good approximation for non-polar liquids, but may be less accurate for polar or associating liquids.

Q3: Can I use this for any temperature?
A: This calculates the normal boiling point (at 1 atm pressure). For other pressures, use the Clausius-Clapeyron equation.

Q4: Where can I find ΔH_vap values?
A: Chemical handbooks, material safety data sheets (MSDS), or thermodynamic databases provide these values.

Q5: How do I convert the result to Celsius?
A: Subtract 273.15 from the Kelvin value to get Celsius.