1. What is the Normal Boiling Point Equation?

The normal boiling point equation \( T_b = \frac{\Delta H_{vap}}{\Delta S_{vap}} \) calculates the temperature at which a liquid boils at 1 atm pressure, given its heat of vaporization and entropy of vaporization.

2. How Does the Calculator Work?

The calculator uses the boiling point equation:

Where:

• \( T_b \) — Normal boiling point (K)
• \( \Delta H_{vap} \) — Heat of vaporization (J/mol)
• \( \Delta S_{vap} \) — Entropy of vaporization (J/mol·K)

Explanation: This equation is derived from the thermodynamic relationship at phase equilibrium, where the Gibbs free energy change is zero at the boiling point.

3. Importance of Boiling Point Calculation

Details: Calculating normal boiling point is essential for chemical process design, separation techniques, and understanding the physical properties of substances in various industrial and research applications.

4. Using the Calculator

Tips: Enter heat of vaporization in J/mol and entropy of vaporization in J/mol·K. Both values must be positive numbers for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the normal boiling point?
A: The normal boiling point is the temperature at which a liquid's vapor pressure equals 1 atmosphere (standard pressure).

Q2: Why is entropy of vaporization important?
A: Entropy of vaporization represents the disorder increase during phase change and is crucial for determining the boiling temperature.

Q3: What are typical values for ΔH_vap and ΔS_vap?
A: ΔH_vap typically ranges from 20-50 kJ/mol, while ΔS_vap is often around 85-90 J/mol·K for many liquids (Trouton's rule).

Q4: Can this equation be used for all substances?
A: This equation works well for many substances but may have limitations for strongly associated liquids or at extreme conditions.

Q5: How does pressure affect boiling point?
A: This equation calculates boiling point at 1 atm. For other pressures, the Clausius-Clapeyron equation should be used.