This page provides supplementary data to the article
properties of water
Water () is a polar inorganic compound that is at room temperature a tasteless and odorless liquid, which is nearly colorless apart from an inherent hint of blue. It is by far the most studied chemical compound and is described as the "univer ...
.
Further comprehensive authoritative data can be found at th
NIST Webbookpage on thermophysical properties of fluids.
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 k
Pa, and ''T'' is temperature in
kelvin
The kelvin, symbol K, is the primary unit of temperature in the International System of Units (SI), used alongside its prefixed forms and the degree Celsius. It is named after the Belfast-born and University of Glasgow-based engineer and phys ...
s.
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 k
Pa. 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 work ''P''Δ''V'' 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., p. 2390
Table of various forms of ice
‡Ice XI triple point is theoretical and has never been obtained
Phase diagram
Water with dissolved NaCl
Note: ρ is density, ''n'' is refractive index at 589 nm, and η is viscosity, all at 20 °C; ''T''
eq is the equilibrium temperature between two phases: ice/liquid solution for ''T''
eq < 0–0.1 °C and NaCl/liquid solution for ''T''
eq above 0.1 °C.
Self-ionization
:
Spectral data
Self-diffusion coefficients
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 t
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
The degree Celsius is the unit of temperature on the Celsius scale (originally known as the centigrade scale outside Sweden), one of two temperature scales used in the International System of Units (SI), the other being the Kelvin scale. The ...
* ''V'' –
specific volume
In thermodynamics, the specific volume of a substance (symbol: , nu) is an intrinsic property of the substance, defined as the ratio of the substance's volume () to its mass (). It is the reciprocal of density (rho) and it is related to the mol ...
in cubic
decimeters per kilogram (1 dm
3 is equivalent to 1 liter)
* ''H'' –
specific enthalpy
Enthalpy , a property of a thermodynamic system, is the sum of the system's internal energy and the product of its pressure and volume. It is a state function used in many measurements in chemical, biological, and physical systems at a constant p ...
in
kilojoules
The joule ( , ; symbol: J) is the unit of energy in the International System of Units (SI). It is equal to the amount of work done when a force of 1 newton displaces a mass through a distance of 1 metre in the direction of the force applied ...
per kilogram
* ''U'' –
specific internal energy
The internal energy of a thermodynamic system is the total energy contained within it. It is the energy necessary to create or prepare the system in its given internal state, and includes the contributions of potential energy and internal kinet ...
in kilojoules per kilogram
* ''S'' – specific
entropy
Entropy is a scientific concept, as well as a measurable physical property, that is most commonly associated with a state of disorder, randomness, or uncertainty. The term and the concept are used in diverse fields, from classical thermodynam ...
in kilojoules per kilogram-kelvin
* ''c
p'' –
specific heat capacity
In thermodynamics, the specific heat capacity (symbol ) of a substance is the heat capacity of a sample of the substance divided by the mass of the sample, also sometimes referred to as massic heat capacity. Informally, it is the amount of heat t ...
at constant pressure in kilojoules per kilogram-kelvin
* ''γ'' –
Thermal expansion coefficient
Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature, usually not including phase transitions.
Temperature is a monotonic function of the average molecular kinetic ...
as 10
−3 per kelvin
* ''λ'' –
Heat conductivity
The thermal conductivity of a material is a measure of its ability to heat conduction, conduct heat. It is commonly denoted by k, \lambda, or \kappa.
Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials ...
in
milliwatts
The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Wat ...
per meter-kelvin
* ''η'' –
Viscosity
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water.
Viscosity quantifies the inte ...
in
micropascal
The pascal (symbol: Pa) is the unit of pressure in the International System of Units (SI), and is also used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is defined a ...
-seconds (1 c
P = 1000 μPa·s)
* ''σ'' –
surface tension
Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to f ...
in
millinewtons per meter (equivalent to dyn/cm)
Standard conditions
In the following table, material data are given for standard pressure of 0.1 M
Pa (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
In thermodynamics, the triple point of a substance is the temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium.. It is that temperature and pressure at which the subli ...
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 are 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 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 used only as approximate values.
[Klaus Scheffler (1981): ''Wasserdampftafeln: thermodynam. Eigenschaften von Wasser u. Wasserdampf bis 800°C u. 800 bar'' (''Water Vapor Tables: Thermodynamic Characteristics of Water and Water Vapor to 800°C and 800 bar''), Berlin .a.][ Ulrich Grigull, Johannes Staub, Peter Schiebener (1990): ''Steam Tables in SI-Units – Wasserdampftafeln.'' Springer-Verlagdima gmbh]
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
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*_The_values_have_various_units_(Pa,_hPa_or_bar),_which_must_be_considered_when_reading_them.
_Formulas
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* 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, ''P
w'' and ''P
i'', are in pascal (unit)">pascals
The pascal (symbol: Pa) is the unit of pressure in the International System of Units (SI), and is also used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. The unit, named after Blaise Pascal, is defined ...
.
Over liquid water
:log
e(''P
w'') = −6094.4642 ''T''
−1 + 21.1249952 − 2.724552×10
−2 ''T'' + 1.6853396×10
−5 ''T''
2 + 2.4575506 log
e(''T'')
For temperature range: 173.15 K to 373.15 K or equivalently −100 °C to 100 °C
Over ice
:log
e(''P
i'') = −5504.4088 ''T''
−1 − 3.5704628 − 1.7337458×10
−2 ''T'' + 6.5204209×10
−6 ''T''
2 + 6.1295027 log
e(''T'')
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
In thermodynamics, the triple point of a substance is the temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium.. It is that temperature and pressure at which the subli ...
of water. The internationally accepted value according to measurements of Guildner, Johnson and Jones (1976) amounts to:
:''P
w''(''t
tp'' = 0.01 °C) = 611.657
Pa ± 0.010
Pa at (1 − ''α'') = 99%
:
Magnetic susceptibility
Accepted standardized value of the magnetic susceptibility of water at 20 °C (room temperature) is −12.97 cm
3/mol.
Accepted standardized value of the magnetic susceptibility of water at 20 °C (room temperature) is −0.702 cm
3/g.
See also
* Properties of water
References
Bibliography
*
*
*
*
External links
Microwave Spectrum (by NIST)by Martin Chaplin, London South Bank University.
{{Water
Chemical data pages
Water chemistry
Chemical data pages cleanup