Calculate The Vapor Pressure of Water at 0 Degrees Celsius

Water's vapor pressure at 0°C is a fundamental property in thermodynamics and meteorology. This calculator uses the Antoine equation to compute the saturation vapor pressure of water at 0 degrees Celsius, providing both the result and a visual representation of the pressure curve.

Introduction

The vapor pressure of water at 0°C is approximately 4.58 torr (0.611 kPa). This value is crucial for understanding phase transitions, humidity calculations, and industrial processes involving water.

Vapor pressure is the pressure exerted by water molecules in their gaseous state above a liquid water surface. At 0°C, water exists in a solid state (ice), but its vapor pressure can still be calculated using thermodynamic models.

Antoine Equation

The Antoine equation is an empirical relationship used to calculate vapor pressure based on temperature:

log₁₀(P) = A - (B / (T + C))

Where:

P = vapor pressure (mmHg or torr)
T = temperature (°C)
A, B, C = Antoine coefficients for water

For water, the Antoine coefficients are typically:

A = 8.07131
B = 1730.63
C = 233.426

Calculation Example

To calculate the vapor pressure of water at 0°C:

Plug the values into the Antoine equation:

log₁₀(P) = 8.07131 - (1730.63 / (0 + 233.426))

= 8.07131 - (1730.63 / 233.426)

= 8.07131 - 7.414

= 0.65731
Convert the logarithmic result to linear scale:

P = 10^0.65731 ≈ 4.58 torr

This confirms that the vapor pressure of water at 0°C is approximately 4.58 torr.

Interpreting Results

The vapor pressure of water at 0°C indicates:

The partial pressure of water vapor in equilibrium with ice at this temperature
That water molecules are escaping the ice surface at this pressure
Relative humidity calculations when comparing to ambient pressure

Note: At 0°C, water exists as ice, so this vapor pressure represents the equilibrium between ice and water vapor, not liquid water.

FAQ

What is the vapor pressure of water at 0°C?: Approximately 4.58 torr (0.611 kPa) at 0°C.
Why is the vapor pressure of ice different from liquid water?: Ice has a lower vapor pressure than liquid water at the same temperature because the molecular arrangement in ice is more ordered.
How does temperature affect water's vapor pressure?: Vapor pressure increases exponentially with temperature according to the Antoine equation.
What units are used for vapor pressure in this calculator?: The calculator provides results in torr (mmHg) and kPa.
Can I use this calculator for temperatures below 0°C?: Yes, the calculator works for temperatures between -100°C and 200°C.