1. What is Partial Pressure of Water Vapor?

The partial pressure of water vapor is the pressure that water vapor would exert if it alone occupied the volume of a gas mixture at the same temperature. It's a key parameter in humidity calculations and gas mixture analysis.

2. How Does the Calculator Work?

The calculator uses Dalton's Law of Partial Pressures:

Where:

• \( P_{H_2O} \) — Partial pressure of water vapor (atm)
• \( X_{H_2O} \) — Mole fraction of water in the gas mixture (unitless)
• \( P_{total} \) — Total pressure of the gas mixture (atm)

Alternative: For pure water systems, the vapor pressure can be obtained from standard tables at the given temperature.

3. Importance of Water Vapor Pressure

Details: Water vapor pressure is crucial for calculating humidity, dew point, and in various industrial processes like drying, distillation, and HVAC system design.

4. Using the Calculator

Tips: Enter the mole fraction of water (between 0 and 1) and the total system pressure. The calculator will compute the partial pressure of water vapor in the mixture.

5. Frequently Asked Questions (FAQ)

Q1: What is mole fraction?
A: Mole fraction is the ratio of moles of water vapor to the total moles of all components in the gas mixture.

Q2: How does temperature affect water vapor pressure?
A: Vapor pressure increases exponentially with temperature according to the Clausius-Clapeyron equation.

Q3: What are typical values for water vapor pressure?
A: At room temperature (25°C), pure water has a vapor pressure of about 0.0313 atm (23.76 mmHg).

Q4: When is this calculation most useful?
A: For gas mixtures where water is one component, especially in humid air calculations and chemical processes.

Q5: How accurate is this calculation?
A: It's theoretically exact for ideal gas mixtures. For real gases at high pressures, corrections may be needed.