1. What is Ethanol Vapor Pressure?

Ethanol vapor pressure is the pressure exerted by ethanol vapor in thermodynamic equilibrium with its condensed phases at a given temperature. It's an important property for distillation, fuel blending, and industrial processes.

2. How Does the Calculator Work?

The calculator uses the Antoine equation:

Where:

• \( P \) — Vapor pressure (kPa)
• \( T \) — Temperature (K)
• 18.911, 3803.98, 204.64 — Antoine coefficients for ethanol

Explanation: The Antoine equation describes the relation between vapor pressure and temperature for pure components.

3. Importance of Vapor Pressure Calculation

Details: Vapor pressure is crucial for designing distillation columns, predicting evaporation rates, and understanding fuel volatility in engines.

4. Using the Calculator

Tips: Enter temperature in Kelvin (K). The equation is valid for temperatures between 159 K and 374 K.

5. Frequently Asked Questions (FAQ)

Q1: What are typical ethanol vapor pressure values?
A: At room temperature (298 K), ethanol vapor pressure is about 7.87 kPa. At boiling point (351 K), it's 101.325 kPa.

Q2: How does vapor pressure change with temperature?
A: Vapor pressure increases exponentially with temperature according to the Antoine equation.

Q3: What are the limitations of this equation?
A: The equation is accurate for pure ethanol. For ethanol-water mixtures, more complex models are needed.

Q4: Why use Kelvin instead of Celsius?
A: Thermodynamic equations typically require absolute temperature (Kelvin) for proper calculation.

Q5: How does this compare to water vapor pressure?
A: Ethanol has higher vapor pressure than water at the same temperature, which enables separation by distillation.