1. What is the Evaporation Rate Formula?

The evaporation rate formula calculates the molar rate of evaporation based on vapor pressure difference, surface area, gas constant, and temperature. It's commonly used in chemical engineering and environmental science.

2. How Does the Calculator Work?

The calculator uses the evaporation rate equation:

Where:

• \( \Delta P \) — Vapor pressure difference (Pa)
• \( A \) — Surface area (m²)
• \( R \) — Universal gas constant (8.314 J/mol·K)
• \( T \) — Absolute temperature (K)

Explanation: The equation relates the driving force for evaporation (ΔP) to the rate of mass transfer, normalized by the gas constant and temperature.

3. Importance of Evaporation Rate Calculation

Details: Calculating evaporation rates is essential for designing distillation systems, predicting environmental water loss, and modeling industrial drying processes.

4. Using the Calculator

Tips: Enter all values in SI units. Temperature must be in Kelvin (K = °C + 273.15). The gas constant is pre-filled with the standard value of 8.314 J/mol·K.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for evaporation rates?
A: Rates vary widely from 10⁻⁶ to 10⁻² mol/s depending on conditions. Water at room temperature might evaporate at about 10⁻⁴ mol/s per m².

Q2: How does temperature affect evaporation rate?
A: Higher temperatures exponentially increase vapor pressure (ΔP) while also appearing in the denominator, leading to a net strong increase in evaporation rate with temperature.

Q3: What if my substance isn't water?
A: The formula works for any substance, but you must use the correct vapor pressure difference for your specific chemical.

Q4: Does this account for air flow?
A: No, this basic formula assumes still air. For forced convection, additional factors would be needed.

Q5: Why use molar rate instead of mass rate?
A: Molar rate is more fundamental in chemical calculations, though it can be converted to mass rate using molecular weight.