Water (data page)
This page provides supplementary chemical data on water.

# Structure and properties

# Thermodynamic properties

# Liquid Physical Properties

# Water/steam equilibrium properties
Vapor pressure formula for steam in equilibrium with liquid water:
where P is equilibrium vapor pressure in kPa, and T is temperature in kelvins.
for T = 273 K to 333 K: A = 7.2326; B = 1750.286; C = 38.1
for T = 333 K to 423 K: A = 7.0917; B = 1668.21; C = 45.1
Data in the table above is given for water-steam equilibria at various temperatures over the entire temperature range at which liquid water can exist. Pressure of the equilibrium is given in the second column in kPa. The third column is the heat content of each gram of the liquid phase relative to water at 0 C. The fourth column is the heat of vaporization of each gram of liquid that changes to vapor. The fifth column is the PV work done by each gram of liquid that changes to vapor. The sixth column is the density of the vapor.

# Melting point of ice at various pressures
Data obtained from CRC Handbook of Chemistry and Physics 44th ed., p2390

# Table of various forms of ice
Ice XI triple point is theoretical and has never been obtained

# Phase diagram
File:WaterPhaseDiagram.png

# Self ionization
File:Temperature dependence water ionization pKw on T.svg

# Spectral data

# Additional data translated from German "Wasser (Stoffdaten)" page
The data that follows was copied and translated from the German language Wikipedia version of this page (which has moved to here). It provides supplementary physical, thermodynamic, and vapor pressure data, some of which is redundant with data in the tables above, and some of which is additional.

## Physical and thermodynamic tables
In the following tables, values are temperature dependent and to a lesser degree pressure dependent, and are arranged by state of aggregation (s=solid, lq=liquid, g=gas), which are clearly a function of temperature and pressure. All of the data were computed from data given in "Formulation of the Thermodynamic Properties of Ordinary Water Substance for Scientific and General Use" (1984). This applies to:
- T - temperature in degrees Celsius
- V - specific volume in decimeter3 per kilogram (1 dm3 is equivalent to 1 liter)
- H - specific enthalpy in kJ per kilogram
- U - internal energy in kJ per kilogram
- S - specific entropy in kJ per kilogram-kelvin
- cp - specific (constant pressure) heat capacity in kJ per kilogram-kelvin
-  - Thermal expansion coefficient as 103 per kelvin
-  - Heat conductivity in milliwatt  per meter-kelvin
-  - Viscosity  in micropascal-seconds (1 cP = 1000 Pas)
-  - surface tension in millinewtons per meter (equivalent to dyn/cm)

### Standard conditions
In the following table, material data are given for standard pressure of 0.1 MPa (equivalent to 1 bar). Up to 99.63 C (the boiling point of water at 0.1 MPa), at this pressure water exists as a liquid. Above that, it exists as water vapor. Note that the boiling point of 100.0 C is at a pressure of 0.101325 MPa (1 atm), which is the average atmospheric pressure.

### Triple point
In the following table, material data are given with a pressure of 611.7 Pa (equivalent to 0.006117 bar). Up to a temperature of 0.01 C, the triple point of water, water normally exists as ice, except for supercooled water, for which one data point is tabulated here. At the triple point, ice can exist together with both liquid water and vapor. At higher temperatures, the data is for water vapor only.

## Saturated vapor pressure
The following table is based on different, complementary sources and approximation formulas, whose values are of various quality and accuracy. The values in the temperature range of 100 C to 100 C were inferred from D. Sunday (1982) and are quite uniform and exact. The values in the temperature range of the boiling point of the water up to the critical point (100 C to 374 C), are drawn from different sources and are substantially less accurate, hence they should be understood and used also only as approximate values.
To use the values correctly, consider the following points:
- The values apply only to smooth interfaces and in the absence other gases or gas mixtures such as air. Hence they apply only to pure phases and need a correction factor for systems in which air is present.
- The values were not computed according formulas widely used in the US, but using somewhat more exact formulas (see below), which can also be used to compute further values in the appropriate temperature ranges.
- The saturated vapor pressure over water in the temperature range of 100 C to 50 C is only extrapolated .
- The values have various units (Pa, hPa or bar), which must be considered when reading them.

### Formulas
The table values for 100 C to 100 C were computed by the following formulas, where T is in kelvins and vapor pressures, Pw and Pi, are in pascals.
Over liquid water
For temperature range: 173.15 K to 373.15 K or equivalently 100 C to 100 C
Over ice
For temperature range: 173.15 K to 273.15 K or equivalently 100 C to 0 C
At triple point
An important basic value, which is not registered in the table, is the saturated vapor pressure at the triple point of water. The internationally accepted value according to measurements of Guildner, Johnson and Jones (1976) amounts to: