Vapor Pressure of Water Calculator

Vapor pressure strongly depends on temperature, modeled via various empirical curves established through experimentation. One of the most common methods is the Antoine equation, expressed as log10(P) = A - (B / (T + C)), where P represents pressure and T represents temperature. Other formulations, including the Magnus, Tetens, and Buck equations, utilize exponential functions of temperature to calculate saturation vapor pressure over liquid water or ice with high precision across different temperature ranges.

Let us calculate the vapor pressure of water at a temperature of 80 degrees Celsius using the Antoine formulation variant: Antoine_pressure_1 = 10^(8.07131 - (1730.63 / (233.426 + 80))). First, evaluate the denominator inside the fraction: 233.426 + 80 = 313.426. Next, divide 1730.63 by 313.426, which yields approximately 5.5216. Subtract this value from 8.07131 to get 2.54971. Finally, compute 10 raised to the power of 2.54971, resulting in approximately 354.58 millimeters of mercury (mmHg) or roughly 47.3 kilopascals, demonstrating how rapidly vapor pressure climbs as thermal energy increases.

Always verify the temperature scale required by your chosen empirical model, as some equations expect Celsius while others necessitate Kelvin. Select the appropriate formulation depending on your phase of interest; using formulas meant for liquid water below freezing will yield inaccurate results. Keep in mind that minor variations in temperature input can significantly alter output values due to the exponential nature of vapor pressure curves.