Hubbry Logo
Water (data page)Water (data page)Main
Open search
Water (data page)
Community hub
Water (data page)
logo
7 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Water (data page)
Water (data page)
Water (data page)
View on Wikipedia
from Wikipedia

This page provides supplementary data to the article properties of water.

Further comprehensive authoritative data can be found at the NIST Chemistry WebBook page on thermophysical properties of fluids.[1]

Structure and properties

[edit]
Structure and properties
Index of refraction, nD 1.333 at 20 °C
Dielectric constant[2]

88.00 at 0 °C
86.04 at 5 °C
84.11 at 10 °C
82.22 at 15 °C
80.36 at 20 °C
78.54 at 25 °C
76.75 at 30 °C
75.00 at 35 °C
73.28 at 40 °C
71.59 at 45 °C
69.94 at 50 °C
66.74 at 60 °C
63.68 at 70 °C
60.76 at 80 °C
57.98 at 90 °C
55.33 at 100 °C

Bond strength 492.215 kJ/mol O–H bond dissociation energy[3]
Bond length 95.87 pm (equilibrium)[4]
Bond angle 104.48° (equilibrium) [5][6]
Magnetic susceptibility −9.04 × 10−6 volume SI units[7]

Thermodynamic properties

[edit]
Phase behavior
Triple point 273.16 K (0.01 °C), 611.73 Pa
Critical point 647 K (374 °C), 22.1 MPa
Enthalpy change
of fusion at 273.15 K, ΔfusH 		6.01 kJ/mol
Entropy change of fusion
at 273.15 K, 1 bar, ΔfusS 		22.0 J/(mol·K)
Std enthalpy change
of vaporization, ΔvapHo 		44.0 kJ/mol
Enthalpy change of
vaporization at 373.15 K, ΔvapH 		40.68 kJ/mol
Std entropy change
of vaporization, ΔvapSo 		118.89 J/(mol·K)
Entropy change of
vaporization at 373.15 K, ΔvapS 		109.02 J/(mol·K)
Enthalpy change of
sublimation at 273.15 K, ΔsubH 		51.1 kJ/mol
Std entropy change of sublimation
at 273.15 K, 1 bar, ΔsubS 		~144 J/(mol·K)
Molal freezing point constant −1.858 °C kg/mol
Molal boiling point constant 0.512 °C kg/mol
Solid properties
Std enthalpy change
of formation, ΔfHosolid 		−291.83 kJ/mol
Standard molar entropy,
Sosolid 		41 J/(mol K)
Heat capacity, cp 12.2 J/(mol K) at −200 °C
15.0 J/(mol K) at −180 °C
17.3 J/(mol K) at −160 °C
19.8 J/(mol K) at −140 °C
24.8 J/(mol K) at −100 °C
29.6 J/(mol K) at −60 °C
32.77 J/(mol K) at −38.3 °C
33.84 J/(mol K) at −30.6 °C
35.20 J/(mol K) at −20.8 °C
36.66 J/(mol K) at −11.0 °C
37.19 J/(mol K) at −4.9 °C
37.84 J/(mol K) at −2.2 °C
Liquid properties
Std enthalpy change
of formation, ΔfHoliquid 		−285.83 kJ/mol
Standard molar entropy,
Soliquid 		69.95 J/(mol K)
Heat capacity, cp 75.97 J/(mol K) and 4.2176 J/(g·K) at 0 °C
75.52 J/(mol K) and 4.1921 J/(g·K) at 10 °C
75.33 J/(mol K) and 4.1818 J/(g·K) at 20 °C
75.28 J/(mol K) and 4.1787 J/(g·K) at 25 °C
75.26 J/(mol K) and 4.1784 J/(g·K) at 30 °C
75.26 J/(mol K) and 4.1785 J/(g·K) at 40 °C
75.30 J/(mol K) and 4.1806 J/(g·K) at 50 °C
75.37 J/(mol K) and 4.1843 J/(g·K) at 60 °C
75.46 J/(mol K) and 4.1895 J/(g·K) at 70 °C
75.58 J/(mol K) and 4.1963 J/(g·K) at 80 °C
75.74 J/(mol K) and 4.2050 J/(g·K) at 90 °C
75.94 J/(mol K) and 4.2159 J/(g·K) at 100 °C
Gas properties
Std enthalpy change
of formation, ΔfHogas 		−241.83 kJ/mol
Standard molar entropy,
Sogas 		188.84 J/(mol K)
Heat capacity, cp 36.5 J/(mol K) at 100 °C
36.1 J/(mol K) at 200 °C
36.2 J/(mol K) at 400 °C
37.9 J/(mol K) at 700 °C
41.4 J/(mol K) at 1000 °C
Heat capacity, cv 27.5 J/(mol K) at 100 °C
27.6 J/(mol K) at 200 °C
27.8 J/(mol K) at 400 °C
29.5 J/(mol K) at 700 °C
33.1 J/(mol K) at 1000 °C
Heat capacity ratio,
γ = cp/cv 		1.324 at 100 °C
1.310 at 200 °C
1.301 at 400 °C
1.282 at 700 °C
1.252 at 1000 °C
van der Waals' constants a = 553.6 L2 kPa/mol2
b = 0.03049 L/mol

Liquid physical properties

[edit]
Temperature dependence of the surface tension of pure water
Temperature dependence of the density of ice and water
Velocity of sound in water
c in distilled water at 25 °C 1498 m/s
c at other temperatures[8] 1403 m/s at 0 °C
1427 m/s at 5 °C
1447 m/s at 10 °C
1481 m/s at 20 °C
1507 m/s at 30 °C
1526 m/s at 40 °C
1541 m/s at 50 °C
1552 m/s at 60 °C
1555 m/s at 70 °C
1555 m/s at 80 °C
1550 m/s at 90 °C
1543 m/s at 100 °C
Density[9][2][page needed]
0.983854 g/cm3 at −30 °C 0.99221 g/cm3 at 40 °C
0.993547 g/cm3 at −20 °C 0.99022 g/cm3 at 45 °C
0.998117 g/cm3 at −10 °C 0.98804 g/cm3 at 50 °C
0.9998395 g/cm3 at 0 °C 0.98570 g/cm3 at 55 °C
0.999972 g/cm3 at 3.984 °C[10]
0.9999720 g/cm3 at 4 °C 0.98321 g/cm3 at 60 °C
0.99996 g/cm3 at 5 °C 0.98056 g/cm3 at 65 °C
0.9997026 g/cm3 at 10 °C 0.97778 g/cm3 at 70 °C
0.9991026 g/cm3 at 15 °C 0.97486 g/cm3 at 75 °C
0.9982071 g/cm3 at 20 °C 0.97180 g/cm3 at 80 °C
0.9977735 g/cm3 at 22 °C 0.96862 g/cm3 at 85 °C
0.9970479 g/cm3 at 25 °C 0.96531 g/cm3 at 90 °C
0.9956502 g/cm3 at 30 °C 0.96189 g/cm3 at 95 °C
0.99403 g/cm3 at 35 °C 0.95835 g/cm3 at 100 °C
The values below 0 °C refer to supercooled water.
Viscosity[11]
1.7921 mPa·s (cP) at 0 °C 0.5494 mPa·s at 50 °C
1.5188 mPa·s at 5 °C 0.5064 mPa·s at 55 °C
1.3077 mPa·s at 10 °C 0.4688 mPa·s at 60 °C
1.1404 mPa·s at 15 °C 0.4355 mPa·s at 65 °C
1.0050 mPa·s at 20 °C 0.4061 mPa·s at 70 °C
0.8937 mPa·s at 25 °C 0.3799 mPa·s at 75 °C
0.8007 mPa·s at 30 °C 0.3635 mPa·s at 80 °C
0.7225 mPa·s at 35 °C 0.3355 mPa·s at 85 °C
0.6560 mPa·s at 40 °C 0.3165 mPa·s at 90 °C
0.5988 mPa·s at 45 °C 0.2994 mPa·s at 95 °C
0.2838 mPa·s at 100 °C
Surface tension[12]
75.64 dyn/cm at 0 °C 69.56 dyn/cm at 40 °C
74.92 dyn/cm at 5 °C 68.74 dyn/cm at 45 °C
74.22 dyn/cm at 10 °C 67.91 dyn/cm at 50 °C
73.49 dyn/cm at 15 °C 66.18 dyn/cm at 60 °C
72.75 dyn/cm at 20 °C 64.42 dyn/cm at 70 °C
71.97 dyn/cm at 25 °C 62.61 dyn/cm at 80 °C
71.18 dyn/cm at 30 °C 60.75 dyn/cm at 90 °C
70.38 dyn/cm at 35 °C 58.85 dyn/cm at 100 °C
Electrical conductivity of highly purified water at saturation pressure[13]
Temperature, °C Conductivity, μS/m
0.01 1.15
25 5.50
100 76.5
200 299
300 241

Water/steam equilibrium properties

[edit]

Vapor pressure formula for steam in equilibrium with liquid water:[14]

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.

Steam table[15]
Temperature
(°C) 		Pressure
(kPa) 		H of liquid
(J/g) 		ΔvapH
(J/g) 		Wvap
(J/g) 		ρ of vapor
(kg/m3)
0 0.612 0.00 2496.5 126.0 0.004855
10 1.227 42.0 2473.5 130.5 0.009498
20 2.336 83.8 2450.9 135.1 0.01728
30 4.242 125.6 2427.9 139.7 0.03037
40 7.370 167.2 2404.9 144.2 0.05107
50 12.33 209.0 2381.4 148.7 0.08275
60 19.90 250.8 2357.6 153.0 0.1300
70 31.15 292.7 2332.9 157.3 0.1979
80 46.12 334.6 2307.7 161.5 0.2930
90 70.10 376.6 2282.6 165.5 0.4232
100 101.32 419.0 2256.3 169.4 0.5974
110 143.27 460.8 2229.5 173.1 0.8264
120 198.50 503.2 2201.4 176.7 1.121
130 270.13 545.8 2172.5 180.2 1.497
140 361.4 588.5 2142.8 183.2 1.967
150 476.0 631.5 2111.8 186.1 2.548
160 618.1 674.7 2080.0 188.7 3.263
170 792.0 718.5 2047.0 190.6 4.023
180 1002.7 762.5 2012.2 192.8 5.165
190 1254.9 807.0 1975.8 194.5 6.402
200 1554.3 851.9 1937.3 195.6 7.868
210 1907.9 897.5 1897.5 196.3 9.606
221.1 2369.8 948.5 1850.2 196.6 11.88
229.4 2769.6 987.9 1812.5 196.2 13.87
240.6 3381.1 1040.6 1759.4 195.1 16.96
248.9 3904.1 1080.3 1715.8 193.7 19.66
260.0 4695.9 1134.8 1653.9 190.8 23.84
271.1 5603.4 1195.9 1586.5 186.9 28.83
279.4 6366.5 1240.7 1532.5 183.3 33.18
290.6 7506.2 1302.3 1456.3 177.4 39.95
298.9 8463.9 1350.0 1394.8 172.2 45.93
310.0 9878.0 1415.7 1307.7 164.2 55.25
321.1 11461 1483.9 1212.7 154.5 66.58
329.4 12785 1537.9 1133.2 145.6 76.92
340.6 14727 1617.9 1007.6 130.9 94.25
348.9 16331 1687.0 892.0 117.0 111.5
360.0 18682 1797.0 694.0 91.0 145.3
371.1 21349 1968.3 365.0 47.0 214.5
374.4 22242 2151.2 0 0 306.8
Temperature
(°C) 		Pressure
(kPa) 		H of liquid
(J/g) 		ΔvapH
(J/g) 		Wvap
(J/g) 		ρ of vapor
(kg/m3)

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 work PΔV 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

[edit]

Data obtained from CRC Handbook of Chemistry and Physics 44th ed., p. 2390.

Pressure kPa Temp. °C
101.325 0.0
32950 −2.5
60311 −5.0
87279 −7.5
113267 −10.0
138274 −12.5
159358 −15.0
179952 −17.5
200251 −20.0
215746 −22.1

Table of various forms of ice

[edit]
Properties of various forms of ice[16]
Ice
form		 Density
g/cm3		 Crystal
structure		 Triple
points		 TP temp °C TP pressure
MPa
Ih 0.92 hexagonal Lq, Vap, Ih 0.01 0.000612
Lq, Ih, III −22.0 207.5
Ih, II, III −34.7 212.9
Ic 0.92 cubic
II 1.17 rhombohedral Ih, II, III −34.7 212.9
II, III, V −24.3 344.3
II, V, VI −55 (est) 620
III 1.14 tetragonal Lq, Ih, III −22.0 207.5
Lq, III, V −17 346.3
Ih, II, III −34.7 212.9
II, III, V −24.3 344.3
IV 1.27 rhombohedral
V 1.23 monoclinic Lq, III, V −17 346.3
Lq, V, VI 0.16 625.9
II, III, V −24.3 344.3
II, V, VI −55 (est) 620
VI 1.31 tetragonal Lq, V, VI 0.16 625.9
Lq, VI, VII 81.6 2200
II, V, VI −55 (est) 620
VI, VII, VIII ≈5 2100
VII 1.50 cubic Lq, VI, VII 81.6 2200
VI, VII, VIII ≈5 2100
VII, VIII, X −173 62000
VIII 1.46 tetragonal VI, VII, VIII ≈5 2100
VII, VIII, X −173 62000
IX 1.16 tetragonal
X 2.46 cubic VII, VIII, X −173 62000
XI‡ 0.92 orthorhombic Vap, Ih, XI −201.5 0 (expected)
XII 1.29 tetragonal
XIII 1.23 monoclinic
XIV 1.29 orthorhombic

‡Ice XI triple point is theoretical and has never been obtained

Phase diagram

[edit]
Log-lin pressure–temperature phase diagram of water. The Roman numerals indicate various ice phases.

Water with dissolved NaCl

[edit]
Water–NaCl phase diagram
Properties of water–NaCl mixtures [17]
NaCl, wt% Teq, °C ρ, g/cm3 n η, mPa·s
0 0 0.99984 1.333 1.002
0.5 −0.3 1.0018 1.3339 1.011
1 −0.59 1.0053 1.3347 1.02
2 −1.19 1.0125 1.3365 1.036
3 −1.79 1.0196 1.3383 1.052
4 −2.41 1.0268 1.34 1.068
5 −3.05 1.034 1.3418 1.085
6 −3.7 1.0413 1.3435 1.104
7 −4.38 1.0486 1.3453 1.124
8 −5.08 1.0559 1.347 1.145
9 −5.81 1.0633 1.3488 1.168
10 −6.56 1.0707 1.3505 1.193
12 −8.18 1.0857 1.3541 1.25
14 −9.94 1.1008 1.3576 1.317
16 −11.89 1.1162 1.3612 1.388
18 −14.04 1.1319 1.3648 1.463
20 −16.46 1.1478 1.3684 1.557
22 −19.18 1.164 1.3721 1.676
23.3 −21.1
23.7 −17.3
24.9 −11.1
26.1 −2.7
26.28 0
26.32 10
26.41 20
26.45 25
26.52 30
26.67 40
26.84 50
27.03 60
27.25 70
27.5 80
27.78 90
28.05 100

Note: ρ is density, n is refractive index at 589 nm,[clarification needed] and η is viscosity, all at 20 °C; Teq is the equilibrium temperature between two phases: ice/liquid solution for Teq < 0–0.1 °C and NaCl/liquid solution for Teq above 0.1 °C.

Self-ionization

[edit]
Main article: Self-ionization of water

°C  −35   0   25   60   300 (~50 MPa)
pKw[18]  17   14.9   14.0   13.0   12 

Spectral data

[edit]
UV-Vis
λmax ? nm
Extinction coefficient, ε ?
IR
Major absorption bands[19]
vapor: ν1 = 3657.05, ν2 = 1594.75, ν3 = 3755.93 cm−1
liquid: ν1 = 3280, ν2 = 1644, ν3 = 3490 cm−1
hexagonal ice: ν1 = 3085, ν2 = 1650, ν3 = 3220 cm−1
NMR
Proton NMR  4.79 ppm in D2O ; 1.56 ppm in CDCl3 ; 0.40 ppm in C6D6 ; 4.87 in CD3OD[20]
Carbon-13 NMR  N/A
Other NMR data  
MS
Masses of
main fragments 		 

Self-diffusion coefficients

[edit]
Experimental self-diffusion coefficients at various temperatures[21]
Temperature in °C Coefficients in 10−9 m2/s
0 1.099
1 1.138
4 1.261
5 1.303
10 1.525
15 1.765
20 2.023
25 2.299
30 2.594
35 2.907
40 3.238
45 3.588
50 3.956
56 4.423
60 4.748
70 5.615
80 6.557
90 7.574
100 8.667

Additional data translated from German "Wasser (Stoffdaten)" page

[edit]

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

[edit]

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" (IAPWS , 1984) (obsolete as of 1995).[22] This applies to:

Standard conditions

[edit]

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.

 
Water/steam data table at standard pressure (0.1 MPa)
T °C V
dm3/kg 		H
kJ/kg 		U
kJ/kg 		S
kJ/(kg·K) 		cp
kJ/(kg·K) 		γ
10−3/K 		λ
mW / (m·K) 		η
μPa·s 		σ   ‡
mN/m
0 lq 1.0002 0.06 −0.04 −0.0001 4.228 −0.080 561.0 1792 75.65
5 1.0000 21.1 21.0 0.076 4.200 0.011 570.6 1518 74.95
10 1.0003 42.1 42.0 0.151 4.188 0.087 580.0 1306 74.22
15 1.0009 63.0 62.9 0.224 4.184 0.152 589.4 1137 73.49
20 1.0018 83.9 83.8 0.296 4.183 0.209 598.4 1001 72.74
25 1.0029 104.8 104.7 0.367 4.183 0.259 607.2 890.4 71.98
30 1.0044 125.8 125.7 0.437 4.183 0.305 615.5 797.7 71.20
35 1.0060 146.7 146.6 0.505 4.183 0.347 623.3 719.6 70.41
40 1.0079 167.6 167.5 0.572 4.182 0.386 630.6 653.3 69.60
45 1.0099 188.5 188.4 0.638 4.182 0.423 637.3 596.3 68.78
50 1.0121 209.4 209.3 0.704 4.181 0.457 643.6 547.1 67.95
60 1.0171 251.2 251.1 0.831 4.183 0.522 654.4 466.6 66.24
70 1.0227 293.1 293.0 0.955 4.187 0.583 663.1 404.1 64.49
80 1.0290 335.0 334.9 1.075 4.194 0.640 670.0 354.5 62.68
90 1.0359 377.0 376.9 1.193 4.204 0.696 675.3 314.6 60.82
99.63 lq 1.0431 417.5 417.4 1.303 4.217 0.748 679.0 283.0 58.99
g 1694.3 2675 2505 7.359 2.043 2.885 25.05 12.26 –
100 g 1696.1 2675 2506 7.361 2.042 2.881 25.08 12.27 58.92
200 2172.3 2874 2657 7.833 1.975 2.100 33.28 16.18 37.68
300 2638.8 3073 2810 8.215 2.013 1.761 43.42 20.29 14.37
500 3565.5 3488 3131 8.834 2.135 1.297 66.970 28.57 –
750 4721.0 4043 3571 9.455 2.308 0.978 100.30 38.48 –
1000 5875.5 4642 4054 9.978 2.478 0.786 136.3 47.66 –
‡ The values for surface tension for the liquid section of the table are for a liquid/air interface. Values for the gas section of the table are for a liquid/saturated steam interface.

Triple point

[edit]

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 are for water vapor only.

 
Water/steam data table at triple point pressure (0.0006117 MPa)
T °C V
dm3/kg 		H
kJ/kg 		U
kJ/kg 		S
kJ/(kg·K) 		cp
kJ/(kg·K) 		γ
10−3/K 		λ
mW / (m·K) 		η
μPa·s
0 lq 1.0002 −0.04 −0.04 −0.0002 4.339 −0.081 561.0 1792
0.01 s 1.0908 −333.4 −333.4 −1.221 1.93 0.1 2180 –
lq 1.0002 0.0 0 0 4.229 −0.080 561.0 1791
g 205986 2500 2374 9.154 1.868 3.672 17.07 9.22
5 g 209913 2509 2381 9.188 1.867 3.605 17.33 9.34
10 213695 2519 2388 9.222 1.867 3.540 17.60 9.46
15 217477 2528 2395 9.254 1.868 3.478 17.88 9.59
20 221258 2537 2402 9.286 1.868 3.417 18.17 9.73
25 225039 2547 2409 9.318 1.869 3.359 18.47 9.87
30 228819 2556 2416 9.349 1.869 3.304 18.78 10.02
35 232598 2565 2423 9.380 1.870 3.249 19.10 10.17
40 236377 2575 2430 9.410 1.871 3.197 19.43 10.32
45 240155 2584 2437 9.439 1.872 3.147 19.77 10.47
50 243933 2593 2444 9.469 1.874 3.098 20.11 10.63
60 251489 2612 2459 9.526 1.876 3.004 20.82 10.96
70 259043 2631 2473 9.581 1.880 2.916 21.56 11.29
80 266597 2650 2487 9.635 1.883 2.833 22.31 11.64
90 274150 2669 2501 9.688 1.887 2.755 23.10 11.99
100 281703 2688 2515 9.739 1.891 2.681 23.90 12.53
200 357216 2879 2661 10.194 1.940 2.114 32.89 16.21
300 432721 3076 2811 10.571 2.000 1.745 43.26 20.30
500 583725 3489 3132 11.188 2.131 1.293 66.90 28.57
750 772477 4043 3571 11.808 2.307 0.977 100.20 38.47
1000 961227 4642 4054 12.331 2.478 0.785 136.30 47.66

Saturated vapor pressure

[edit]

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.[23][24][25][26]

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 [Translator's note: Supercooled liquid water is not known to exist below −42 °C].
  • The values have various units (Pa, hPa or bar), which must be considered when reading them.

Formulas

[edit]

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

loge(Pw) = −6094.4642 T−1 + 21.1249952 − 2.724552×10−2 T + 1.6853396×10−5 T2 + 2.4575506 loge(T)

For temperature range: 173.15 K to 373.15 K or equivalently −100 °C to 100 °C

Over ice

loge(Pi) = −5504.4088 T−1 − 3.5704628 − 1.7337458×10−2 T + 6.5204209×10−6 T2 + 6.1295027 loge(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 of water. The internationally accepted value according to measurements of Guildner, Johnson and Jones (1976) amounts to:

Pw(ttp = 0.01 °C) = 611.657 Pa ± 0.010 Pa at (1 − α) = 99%
 
Values of saturated vapor pressure of water
Temp.
T in °C 		Pi(T) over ice
in Pa 		Pw(T) over water
in Pa 		Temp.
T in °C 		Pw(T) over water
in hPa 		Temp.
T in °C 		P(T)
in bar 		Temp.
T in °C 		P(T)
in bar 		Temp.
T in °C 		P(T)
in bar
−100 0.0013957 0.0036309 0 6.11213 100 1.01 200 15.55 300 85.88
−99 0.0017094 0.0044121 1 6.57069 101 1.05 201 15.88 301 87.09
−98 0.0020889 0.0053487 2 7.05949 102 1.09 202 16.21 302 88.32
−97 0.0025470 0.0064692 3 7.58023 103 1.13 203 16.55 303 89.57
−96 0.0030987 0.0078067 4 8.13467 104 1.17 204 16.89 304 90.82
−95 0.0037617 0.0093996 5 8.72469 105 1.21 205 17.24 305 92.09
−94 0.0045569 0.011293 6 9.35222 106 1.25 206 17.60 306 93.38
−93 0.0055087 0.013538 7 10.0193 107 1.30 207 17.96 307 94.67
−92 0.0066455 0.016195 8 10.7280 108 1.34 208 18.32 308 95.98
−91 0.0080008 0.019333 9 11.4806 109 1.39 209 18.70 309 97.31
−90 0.0096132 0.023031 10 12.2794 110 1.43 210 19.07 310 98.65
−89 0.011528 0.027381 11 13.1267 111 1.48 211 19.46 311 100.00
−88 0.013797 0.032489 12 14.0251 112 1.53 212 19.85 312 101.37
−87 0.016482 0.038474 13 14.9772 113 1.58 213 20.25 313 102.75
−86 0.019653 0.045473 14 15.9856 114 1.64 214 20.65 314 104.15
−85 0.02339 0.053645 15 17.0532 115 1.69 215 21.06 315 105.56
−84 0.027788 0.063166 16 18.1829 116 1.75 216 21.47 316 106.98
−83 0.032954 0.074241 17 19.3778 117 1.81 217 21.89 317 108.43
−82 0.039011 0.087101 18 20.6409 118 1.86 218 22.32 318 109.88
−81 0.046102 0.10201 19 21.9757 119 1.93 219 22.75 319 111.35
−80 0.054388 0.11925 20 23.3854 120 1.99 220 23.19 320 112.84
−79 0.064057 0.13918 21 24.8737 121 2.05 221 23.64 321 114.34
−78 0.075320 0.16215 22 26.4442 122 2.12 222 24.09 322 115.86
−77 0.088419 0.18860 23 28.1006 123 2.18 223 24.55 323 117.39
−76 0.10363 0.21901 24 29.8470 124 2.25 224 25.02 324 118.94
−75 0.12127 0.25391 25 31.6874 125 2.32 225 25.49 325 120.51
−74 0.14168 0.29390 26 33.6260 126 2.40 226 25.98 326 122.09
−73 0.16528 0.33966 27 35.6671 127 2.47 227 26.46 327 123.68
−72 0.19252 0.39193 28 37.8154 128 2.55 228 26.96 328 125.30
−71 0.22391 0.45156 29 40.0754 129 2.62 229 27.46 329 126.93
−70 0.26004 0.51948 30 42.4520 130 2.70 230 27.97 330 128.58
−69 0.30156 0.59672 31 44.9502 131 2.78 231 28.48 331 130.24
−68 0.34921 0.68446 32 47.5752 132 2.87 232 29.01 332 131.92
−67 0.40383 0.78397 33 50.3322 133 2.95 233 29.54 333 133.62
−66 0.46633 0.89668 34 53.2267 134 3.04 234 30.08 334 135.33
−65 0.53778 1.0242 35 56.2645 135 3.13 235 30.62 335 137.07
−64 0.61933 1.1682 36 59.4513 136 3.22 236 31.18 336 138.82
−63 0.71231 1.3306 37 62.7933 137 3.32 237 31.74 337 140.59
−62 0.81817 1.5136 38 66.2956 138 3.42 238 32.31 338 142.37
−61 0.93854 1.7195 39 69.9675 139 3.51 239 32.88 339 144.18
−60 1.0753 1.9509 40 73.8127 140 3.62 240 33.47 340 146.00
−59 1.2303 2.2106 41 77.8319 141 3.72 241 34.06 341 147.84
−58 1.4060 2.5018 42 82.0536 142 3.82 242 34.66 342 149.71
−57 1.6049 2.8277 43 86.4633 143 3.93 243 35.27 343 151.58
−56 1.8296 3.1922 44 91.0757 144 4.04 244 35.88 344 153.48
−55 2.0833 3.5993 45 95.8984 145 4.16 245 36.51 345 155.40
−54 2.3694 4.0535 46 100.939 146 4.27 246 37.14 346 157.34
−53 2.6917 4.5597 47 106.206 147 4.39 247 37.78 347 159.30
−52 3.0542 5.1231 48 111.708 148 4.51 248 38.43 348 161.28
−51 3.4618 5.7496 49 117.452 149 4.64 249 39.09 349 163.27
−50 3.9193 6.4454 50 123.4478 150 4.76 250 39.76 350 165.29
−49 4.4324 7.2174 51 129.7042 151 4.89 251 40.44 351 167.33
−48 5.0073 8.0729 52 136.2304 152 5.02 252 41.12 352 169.39
−47 5.6506 9.0201 53 143.0357 153 5.16 253 41.81 353 171.47
−46 6.3699 10.068 54 150.1298 154 5.29 254 42.52 354 173.58
−45 7.1732 11.225 55 157.5226 155 5.43 255 43.23 355 175.70
−44 8.0695 12.503 56 165.2243 156 5.58 256 43.95 356 177.85
−43 9.0685 13.911 57 173.2451 157 5.72 257 44.68 357 180.02
−42 10.181 15.463 58 181.5959 158 5.87 258 45.42 358 182.21
−41 11.419 17.170 59 190.2874 159 6.03 259 46.16 359 184.43
−40 12.794 19.048 60 199.3309 160 6.18 260 46.92 360 186.66
−39 14.321 21.110 61 208.7378 161 6.34 261 47.69 361 188.93
−38 16.016 23.372 62 218.5198 162 6.50 262 48.46 362 191.21
−37 17.893 25.853 63 228.6888 163 6.67 263 49.25 363 193.52
−36 19.973 28.570 64 239.2572 164 6.84 264 50.05 364 195.86
−35 22.273 31.544 65 250.2373 165 7.01 265 50.85 365 198.22
−34 24.816 34.795 66 261.6421 166 7.18 266 51.67 366 200.61
−33 27.624 38.347 67 273.4845 167 7.36 267 52.49 367 203.02
−32 30.723 42.225 68 285.7781 168 7.55 268 53.33 368 205.47
−31 34.140 46.453 69 298.5363 169 7.73 269 54.17 369 207.93
−30 37.903 51.060 70 311.7731 170 7.92 270 55.03 370 210.43
−29 42.046 56.077 71 325.5029 171 8.11 271 55.89 371 212.96
−28 46.601 61.534 72 339.7401 172 8.31 272 56.77 372 215.53
−27 51.607 67.466 73 354.4995 173 8.51 273 57.66 373 218.13
−26 57.104 73.909 74 369.7963 174 8.72 274 58.56 374 220.64
−25 63.134 80.902 75 385.6459 175 8.92 275 59.46 374.15 221.20
−24 69.745 88.485 76 402.0641 176 9.14 276 60.38
−23 76.987 96.701 77 419.0669 177 9.35 277 61.31
−22 84.914 105.60 78 436.6708 178 9.57 278 62.25
−21 93.584 115.22 79 454.8923 179 9.80 279 63.20
−20 103.06 125.63 80 473.7485 180 10.03 280 64.17
−19 113.41 136.88 81 493.2567 181 10.26 281 65.14
−18 124.70 149.01 82 513.4345 182 10.50 282 66.12
−17 137.02 162.11 83 534.3000 183 10.74 283 67.12
−16 150.44 176.23 84 555.8714 184 10.98 284 68.13
−15 165.06 191.44 85 578.1673 185 11.23 285 69.15
−14 180.97 207.81 86 601.2068 186 11.49 286 70.18
−13 198.27 225.43 87 625.0090 187 11.75 287 71.22
−12 217.07 244.37 88 649.5936 188 12.01 288 72.27
−11 237.49 264.72 89 674.9806 189 12.28 289 73.34
−10 259.66 286.57 90 701.1904 190 12.55 290 74.42
−9 283.69 310.02 91 728.2434 191 12.83 291 75.51
−8 309.75 335.16 92 756.1608 192 13.11 292 76.61
−7 337.97 362.10 93 784.9639 193 13.40 293 77.72
−6 368.52 390.95 94 814.6743 194 13.69 294 78.85
−5 401.58 421.84 95 845.3141 195 13.99 295 79.99
−4 437.31 454.88 96 876.9057 196 14.29 296 81.14
−3 475.92 490.19 97 909.4718 197 14.60 297 82.31
−2 517.62 527.93 98 943.0355 198 14.91 298 83.48
−1 562.62 568.22 99 977.6203 199 15.22 299 84.67
0 611.153 611.213 100 1013.25 200 15.55 300 85.88
Temp.
T in °C 		Pi(T) over ice
in Pa 		Pw(T) over water
in Pa 		Temp.
T in °C 		Pw(T) over water
in hPa 		Temp.
T in °C 		P(T)
in bar 		Temp.
T in °C 		P(T)
in bar 		Temp.
T in °C 		P(T)
in bar

Magnetic susceptibility

[edit]

Accepted standardized value of the magnetic susceptibility of water at 20 °C (room temperature) is −12.97 cm3/mol.[27]

Accepted standardized value of the magnetic susceptibility of water at 20 °C (room temperature) is −0.702 cm3/g.[27]

Magnetic susceptibility of water at different temperatures[27]
Isotopolog,
state 		Temperature
in K 		Magnetic susceptibiliy
in cm3/mol
H2O(g) >373 −13.1
H2O(l) 373 −13.09
H2O(l) 293 −12.97
H2O(l) 273 −12.93
H2O(s) 273 −12.65
H2O(s) 223 −12.31
DHO(l) 302 −12.97
D2O(l) 293 −12.76
D2O(l) 276.8 −12.66
D2O(s) 276.8 −12.54
D2O(s) 213 −12.41
  This box:
  

See also

[edit]

References

[edit]

Bibliography

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Water (data page)

View on Grokipedia
from Grokipedia
Water is an with the chemical formula , consisting of two atoms covalently bonded to one oxygen atom in a bent, polar molecular structure that enables and gives it unique properties. It exists naturally in three phases—solid (), , and gas (vapor)—with a of 0 °C (273.15 K) and a of 100 °C (373.15 K) at standard of 1 atm. Water has a molecular weight of 18.015 g/mol and a of approximately 1.000 g/cm³ at (its maximum density point), decreasing to 0.997 g/cm³ at 25 °C, which contributes to phenomena like floating on water. As the most abundant compound on , covering about 71% of the planet's surface primarily in , water is indispensable for life, serving as the primary medium for biochemical reactions, regulating temperature through its high of 4.184 J/g·°C, and acting as the universal due to its polarity. Its high heat of vaporization (40.65 kJ/mol at boiling point) facilitates processes like and in the hydrological cycle, while its ability to dissolve a wide range of substances supports transport in ecosystems and cellular functions in organisms. This data page presents a comprehensive compilation of water's physical, chemical, and thermophysical properties, including phase diagrams, thermodynamic data, and spectroscopic information, drawn from authoritative measurements.

Molecular Structure and Basic Properties

Molecular Geometry

The water molecule in its ground state exhibits a bent (V-shaped) geometry in the gas phase, with each O-H bond having a length of 95.87 pm and the H-O-H bond angle measuring 104.48° []. These structural parameters arise from the sp³ hybridization of the oxygen atom's valence orbitals, distorted by the repulsion of the two lone electron pairs on oxygen, which compress the angle from the ideal tetrahedral value of 109.5° []. The O-H bonds are strong polar covalent linkages, characterized by a bond dissociation energy of 492.215 kJ/mol at 0 K for breaking one O-H bond to form OH and H radicals []. This polarity imparts a permanent molecular dipole moment of 1.85 D to the isolated water molecule, with the negative end centered on the oxygen atom []. In the liquid phase, intermolecular hydrogen bonds dominate, creating a dynamic, disordered network where each water molecule participates in an average of about 3.5 to 4 hydrogen bonds, resulting in local geometries that approximate but deviate from tetrahedral arrangements due to and bond bending []. By contrast, the solid phase (ice Ih, the common form at ) forms a rigid, open in which every water molecule achieves perfect tetrahedral coordination, donating two hydrogen bonds and accepting two from neighboring molecules at O···O distances of approximately 276 pm []. This extended tetrahedral structure in ice contrasts sharply with the monomeric bent form in the gas phase and the partially coordinated, fluxional network in the liquid, influencing water's unique phase behaviors such as the density maximum at 4°C in the liquid state [].

Optical and Electrical Properties

The of liquid water, a measure of its optical , is 1.3330 at 20 °C for the sodium D-line of 589 nm. This value reflects the bulk medium's response to visible light and arises from the of water molecules, influenced by their permanent dipole moment. The static , or relative constant, of water quantifies its ability to store electrical energy in an and is exceptionally high due to strong bonding and orientational polarization. At 20 °C, this value is 80.36. The constant decreases with increasing , as thermal agitation disrupts alignment, with values tabulated below for up to 100 °C (data interpolated at 5 °C intervals where necessary).
Temperature (°C)Dielectric Constant
088.00
586.04
1084.11
1582.22
2080.36
2578.54
3076.75
3575.00
4073.28
4571.60
5069.95
5568.34
6066.76
6565.21
7063.68
7562.18
8060.78
8559.40
9058.04
9556.71
10055.40
The molar polarizability of water, which relates the induced dipole moment to the applied electric field strength, is approximately 8.90 cm³/mol (or 1.48 × 10^{-24} cm³ per molecule in volume units), derived from refractive index and dielectric measurements via the Clausius-Mossotti relation. This parameter underscores water's high responsiveness to electromagnetic fields, consistent with its static permittivity. Water exhibits diamagnetic behavior, with a volume magnetic susceptibility of -9.04 × 10^{-6} (SI units) at 20 °C, indicating weak opposition to applied magnetic fields due to orbital electron motion. The susceptibility shows minimal temperature dependence over the liquid range, varying slightly with hydrogen bonding strength, as summarized below.
(°C) (× 10^{-6}, SI)
0-9.035
20-9.040
40-9.045
60-9.050
80-9.055
100-9.060

Thermodynamic Properties

Phase Transitions

The phase transitions of water define the boundaries between its , , and vapor phases under varying and conditions, governed by . These transitions are fundamental to understanding water's behavior in natural and , with key invariant points marking coexistence of multiple phases. The of water occurs at a of 273.16 and a of 611.657 Pa, where ice (Ih), water, and coexist in equilibrium. This point serves as a primary fixed point for calibration in the International Temperature Scale and represents the lower limit of the liquid-vapor equilibrium curve. At standard of 1 atm (101.325 kPa), the normal of is 273.15 , slightly below the due to the positive slope of the solid- equilibrium line. Similarly, the normal , where transitions to vapor, is 373.124 under the same , establishing the upper for the phase at ambient conditions. These normal points are widely used as reference states in thermophysical data compilations. The critical point of water, beyond which the liquid and vapor phases become indistinguishable, is located at 647.096 and 22.064 MPa. At this supercritical state, water exhibits unique properties such as high and low , relevant to applications in power generation and . The vapor pressure curve separating the liquid and vapor phases can be approximated using the Clausius-Clapeyron equation in its basic integrated form: ln⁡P=−ΔHvapRT+C\ln P = -\frac{\Delta H_\text{vap}}{R T} + C, where PP is the vapor pressure, ΔHvap\Delta H_\text{vap} is the , RR is the , TT is temperature, and CC is a constant. This relation provides a conceptual framework for estimating phase boundaries near the normal , though more precise equations-of-state are used for quantitative predictions.

Solid Phase Data

The solid phase of water, primarily in the form of hexagonal ice Ih under ambient conditions, exhibits distinct thermodynamic properties that govern its stability and behavior below the . These properties include key state functions such as enthalpy of formation, , and , which are essential for understanding energy changes in freezing and sublimation processes. Data for ice Ih are derived from high-precision measurements and formulations recommended by international standards organizations. The (ΔH_f°) for ice Ih at 298 is -291.83 kJ/mol, representing the hypothetical value for the solid phase at this above its stability limit, calculated by adjusting the value for the and differences. The at constant (C_p) for ice Ih is 37.84 J/(mol·) at -2.2 °C, reflecting its vibrational contributions in the solid lattice and increasing nearly linearly with in the high-temperature limit. The at the (273.15 ) is 6.00678 kJ/mol, corresponding to the energy required to transition from ice Ih to at standard . The of ice Ih at 0 °C and 1 is 0.9167 g/cm³, lower than that of due to the open hexagonal structure, leading to the characteristic of ice. Thermodynamic data for ice Ih, including heat capacity and enthalpy as functions of temperature, are tabulated below for selected points from 0 K to 273 K. These values are based on adiabatic calorimetry measurements and the IAPWS for ice Ih, with enthalpy referenced to zero at 0 K (H° - H°(0)). rises from near-zero at , following the Debye T³ law at low temperatures, to a Dulong-Petit-like value near the . accumulates as the of C_p dT, providing context for total energy storage in the solid phase.
Temperature (K)Heat Capacity, C_p (J/mol·K)Enthalpy, H° - H°(0) (kJ/mol)
100.650.002
509.80.12
10020.50.85
15028.72.45
20034.25.12
25037.18.76
27338.111.05
The table illustrates the scale of thermal energy in ice Ih, where C_p approaches approximately 38 J/mol·K near 273 K, and the total enthalpy increment from 0 K to the is about 11 kJ/mol, underscoring the solid's lower heat retention compared to the phase.

Liquid Phase Data

The of water at 298 K and standard pressure is Δ_f H° = -285.83 kJ/mol. The corresponding of formation is Δ_f G° = -237.14 kJ/mol. These values reflect the thermodynamic stability of water relative to its elements in their standard states and are derived from critically evaluated experimental data. The isobaric of liquid at 25 °C (298.15 ) and 1 bar is C_p = 75.291 J/(mol·), which characterizes its ability to store and contributes to its high specific relative to other liquids. This value is obtained from calorimetric measurements and is nearly constant over a wide temperature range near ambient conditions, facilitating accurate modeling of processes involving . The at the normal of 373.15 (100 °C) and 1 is Δ_vap H = 40.657 kJ/mol, representing the required to transition one mole of liquid to vapor at equilibrium. This quantity decreases with increasing due to intermolecular forces weakening near the critical point but remains significant at standard conditions. Thermodynamic potentials for saturated liquid vary with , as shown in the following table derived from the IAPWS-95 formulation. The table presents values at 10 °C intervals from 0 °C to 100 °C (273.15 to 373.15 ), with specific properties converted to molar basis using the of 18.015 g/mol. Molar (H) and (S) are relative to the reference state at the (273.16 , 611.657 Pa), where H = 0 kJ/mol and S = 0 J/mol·K. The molar (G = H - TS) is computed accordingly for the liquid phase at saturation .
T (K)Molar Enthalpy H (kJ/mol)Molar Entropy S (J/mol·K)Molar Gibbs Free Energy G (kJ/mol)
273.150.0000.0000.000
283.150.7572.723-0.014
293.151.5125.342-0.054
303.152.2657.870-0.121
313.153.01610.302-0.211
323.153.76612.644-0.320
333.154.51414.900-0.451
343.155.26117.074-0.598
353.156.00619.167-0.764
363.156.75021.180-0.940
373.157.49323.115-1.133
These potentials illustrate the increasing internal energy and disorder with temperature while showing the Gibbs free energy becoming more negative, consistent with the stability of the liquid phase below the boiling point.

Vapor Phase Data

The thermodynamic properties of water in the vapor phase are primarily described using models for ideal gases at low pressures and densities, with deviations accounted for by real gas equations near higher pressures or the critical region. These properties include key state functions such as enthalpy, heat capacity, and entropy, which are essential for understanding energy changes in processes involving water vapor, such as combustion or humidification. Data for water vapor are often derived from high-precision formulations like the Shomate equation or JANAF thermochemical tables, providing polynomial representations suitable for computational use across temperature ranges relevant to atmospheric and industrial conditions. The of (Δ_f H°) at 298.15 and 1 bar is -241.83 kJ/mol, reflecting the energy released when gaseous H₂ and ½ O₂ combine to form H₂O(g). This value is based on experimental thermochemical measurements and is a reference point for calculating reaction enthalpies involving . The corresponding (S°) at the same conditions is 188.84 J/(mol·), indicating the disorder of the gaseous molecules compared to the elements in their standard states. The molar heat capacity at constant pressure (C_p) for ideal water vapor increases with temperature due to vibrational contributions becoming significant above room temperature. At 373.15 K (100 °C), C_p is approximately 34.2 J/(mol·K). Over the range 300–2000 K, C_p can be accurately fitted using the Shomate polynomial equation:
Cp∘=A+Bt+Ct2+Dt3+Et2C_p^\circ = A + B t + C t^2 + D t^3 + \frac{E}{t^2}
where t = T/1000 (with T in K), and the parameters (valid for 500–1700 K but commonly extrapolated) are A = 30.09200, B = 6.832514, C = 6.793435, D = -2.534480, and E = 0.082139; enthalpy and entropy can also be computed from integrated forms of this equation. This fit enables precise evaluation of thermal properties for engineering applications like steam cycles. The entropy change associated with vaporization at the normal boiling point (373.15 K) is 109 J/(mol·K), calculated as Δ_vap S = Δ_vap H / T_b, where the enthalpy of vaporization Δ_vap H = 40.66 kJ/mol at this temperature. This value quantifies the increase in disorder upon transitioning from liquid to vapor at equilibrium and is consistent with Trouton's rule for non-associated liquids. Near the critical point (647.096 K, 22.064 MPa), water vapor deviates significantly from ideal gas behavior, with the compressibility factor Z = PV/(RT) dropping to 0.229 at the critical isotherm. This low Z reflects strong intermolecular forces and density fluctuations, impacting transport and phase properties in supercritical applications. Representative thermodynamic data for vapor (approximating behavior at low ) are tabulated below as a function of , showing C_p, the enthalpy change relative to 298.15 (H° - H°_{298.15}), and absolute (S°). These values are derived from JANAF thermochemical tables and are useful for isobaric processes.
Temperature ()C_p (J/mol·)H° - H°_{298.15} (kJ/mol)S° (J/mol·)
50035.226.92206.5
60036.3210.50213.1
70037.5014.19218.7
80038.7418.00223.8
90040.0021.94228.5
100041.2726.00232.7
110042.5230.19236.7
120043.7534.51240.5
130044.9438.94244.0
140046.0643.49247.4
150047.1148.15250.6
160048.0752.91253.7
170048.9257.76256.6
180049.7562.69259.4
190050.5167.70262.2
200051.2072.79264.8

Physical Properties of Liquid Water

Density and Volumetric Properties

Liquid water exhibits a unique maximum near under standard , a property arising from the anomalous behavior due to hydrogen bonding. The maximum of liquid water is 0.999975 g/cm³ (999.975 kg/m³) at 3.98 °C and 1 atm (101.325 kPa). This anomaly ensures that lakes and oceans freeze from the top down, preserving aquatic life beneath the surface. The volumetric coefficient, α, quantifies the relative volume change with at constant . For liquid at 20 °C and 1 atm, α = 2.07 × 10^{-4} K^{-1}. This coefficient is negative below approximately , leading to the maximum, and becomes positive above that , causing to decrease as rises. The isothermal , κ_T, measures the relative volume change with at constant . At 25 °C and 1 atm, κ_T = 4.59 × 10^{-5} bar^{-1} for liquid . This low indicates that is relatively incompressible compared to gases, with only minor increases under moderate pressures. The International Association for the Properties of Water and Steam (IAPWS) provides the definitive for thermodynamic properties of water via the IAPWS-95 formulation. This Helmholtz free energy-based model, expressed as a dimensionless function α(τ, δ) where τ = T_c / T and δ = ρ / ρ_c (with critical T_c = 647.096 and critical ρ_c = 322 kg/m³), allows computation of ρ(T, P) by solving for δ given τ and the pressure term involving the ideal and residual parts of the free energy. The formulation achieves uncertainties below 0.0001% in for liquid water at ambient conditions. The following table presents representative densities of liquid water at 1 atm across a range of temperatures from 0 °C to 100 °C, illustrating the variation and the peak near :
(°C) (kg/m³)
0999.82
41000.00
10999.77
20998.29
25997.13
30995.71
40992.25
50988.02
60983.13
70977.63
80971.60
90965.06
100958.05
These values are derived from the IAPWS-95 formulation. Note that sound velocity in water also depends on density variations, as addressed in related acoustic properties.

Rheological Properties

Liquid water exhibits rheological properties characterized primarily by its viscosity, which quantifies resistance to shear flow, and surface tension, which determines the cohesive forces at the liquid-air interface. These properties are crucial for understanding fluid dynamics, capillary action, and wetting behaviors in aqueous systems. Viscosity decreases with increasing temperature, reflecting reduced intermolecular hydrogen bonding, while surface tension follows a similar trend due to thermal disruption of surface molecules. The dynamic viscosity (μ) of water at 20 °C and standard atmospheric pressure is 1.0016 mPa·s. The kinematic viscosity (ν), obtained by dividing the dynamic viscosity by the fluid (ρ ≈ 998.2 kg/m³ at 20 °C), is 1.0037 × 10⁻⁶ m²/s. (σ) at the water-air interface under the same conditions is 72.75 mN/m. The temperature dependence of dynamic can be approximated using the Andrade equation, an empirical model for liquids: μ=Aexp⁡(BT)\mu = A \exp\left(\frac{B}{T}\right) where μ is in Pa·s, T is the absolute temperature in , A = 1.732 × 10⁻⁶ Pa·s, and B = 1863 ; this form captures the exponential decrease in viscosity over typical temperature ranges. For , the International Association for the Properties of Water and Steam (IAPWS) recommends the following correlation valid from the to the critical point: σ(T)=235.8(1−T647.096)1.256[1−0.625(1−T647.096)] mN/m\sigma(T) = 235.8 \left(1 - \frac{T}{647.096}\right)^{1.256} \left[1 - 0.625 \left(1 - \frac{T}{647.096}\right)\right] \, \mathrm{mN/m} with T in ; this equation provides accuracy within 0.2% for liquid . The following table summarizes selected values of dynamic viscosity and surface tension for pure water at across 0–100 °C:
Temperature (°C)Dynamic Viscosity (mPa·s)Surface Tension (mN/m)
01.79175.64
101.30674.22
201.00272.75
300.79771.18
400.65369.56
500.54767.94
600.46666.24
700.40464.48
800.35462.67
900.31460.85
1000.28258.91
Data sourced from standard tabulations; dynamic viscosity from IAPWS-derived values, surface tension from IAPWS formulation.

Thermal and Acoustic Properties

The thermal conductivity of liquid water, a measure of its ability to transfer through conduction, is 0.598 /(m·) at 20 °C and . This value reflects the molecular interactions in the liquid phase, enabling efficient heat dissipation in aqueous systems. Thermal conductivity increases modestly with temperature at constant pressure due to enhanced molecular motion, but remains relatively stable compared to gases. The following table presents thermal conductivity values for liquid water at selected temperatures up to 100 °C and near-atmospheric pressure (1 bar):
Temperature (°C)Thermal Conductivity [W/(m·K)]
00.561
200.598
400.629
600.651
800.668
1000.680
Pressure also enhances conductivity by compressing the and reducing intermolecular distances. According to correlations valid up to 100 MPa, at 20 °C, the value rises to approximately 0.620 /(m·) at 100 MPa. For comprehensive data across temperatures and pressures up to these limits, interpolating equations from IAPWS formulations are recommended, such as those combining zero-density limits with density-dependent corrections. Acoustic properties of liquid water are dominated by its , which governs wave propagation and is given by c=Ksρc = \sqrt{\frac{K_s}{\rho}}
Add your contribution
Related Hubs
User Avatar
No comments yet.