Dynamic viscosity is a material property which describes the resistance of a fluid to shearing flows. It corresponds roughly to the intuitive notion of a fluid's 'thickness'. For instance, honey has a much higher viscosity than water. Viscosity is measured using a viscometer. Measured values span several orders of magnitude. Of all fluids, gases have the lowest viscosities, and thick liquids have the highest.
The values listed in this article are representative estimates only, as they do not account for measurement uncertainties, variability in material definitions, or non-Newtonian behavior.
Kinematic viscosity is dynamic viscosity divided by fluid density. This page lists only dynamic viscosity.
For dynamic viscosity, the SI unit is Pascal-second. In engineering, the unit is usually Poise or centiPoise, with 1 Poise = 0.1 Pascal-second, and 1 centiPoise = 0.01 Poise.
For kinematic viscosity, the SI unit is m^2/s. In engineering, the unit is usually Stoke or centiStoke, with 1 Stoke = 0.0001 m^2/s, and 1 centiStoke = 0.01 Stoke.
For liquid, the dynamic viscosity is usually in the range of 0.001 to 1 Pascal-second, or 1 to 1000 centiPoise. The density is usually on the order of 1000 kg/m^3, i.e. that of water. Consequently, if a liquid has dynamic viscosity of n centiPoise, and its density is not too different from that of water, then its kinematic viscosity is around n centiStokes.
For gas, the dynamic viscosity is usually in the range of 10 to 20 microPascal-seconds, or 0.01 to 0.02 centiPoise. The density is usually on the order of 0.5 to 5 kg/m^3. Consequently, its kinematic viscosity is around 2 to 40 centiStokes.
Here "standard conditions" refers to temperatures of 25 °C and pressures of 1 atmosphere. Where data points are unavailable for 25 °C or 1 atmosphere, values are given at a nearby temperature/pressure.
The temperatures corresponding to each data point are stated explicitly. By contrast, pressure is omitted since gaseous viscosity depends only weakly on it.
The simple structure of noble gas molecules makes them amenable to accurate theoretical treatment. For this reason, measured viscosities of the noble gases serve as important tests of the kinetic-molecular theory of transport processes in gases (see Chapman–Enskog theory). One of the key predictions of the theory is the following relationship between viscosity , thermal conductivity , and specific heat :
where is a constant which in general depends on the details of intermolecular interactions, but for spherically symmetric molecules is very close to . [1]
This prediction is reasonably well-verified by experiments, as the following table shows. Indeed, the relation provides a viable means for obtaining thermal conductivities of gases since these are more difficult to measure directly than viscosity. [1] [2]
Substance | Molecular formula | Viscosity (μPa·s) | Thermal conductivity (W m−1K−1) | Specific heat (J K−1kg−1) | Notes | Refs. | |
---|---|---|---|---|---|---|---|
Helium | He | 19.85 | 0.153 | 3116 | 2.47 | [2] [3] | |
Neon | Ne | 31.75 | 0.0492 | 618 | 2.51 | [2] [3] | |
Argon | Ar | 22.61 | 0.0178 | 313 | 2.52 | [2] [3] | |
Krypton | Kr | 25.38 | 0.0094 | 149 | 2.49 | [2] [3] | |
Xenon | Xe | 23.08 | 0.0056 | 95.0 | 2.55 | [2] [3] | |
Radon | Rn | ≈26 | ≈0.00364 | 56.2 | T = 26.85 °C; calculated theoretically; estimated assuming | [4] | |
Substance | Molecular formula | Viscosity (μPa·s) | Notes | Ref. |
---|---|---|---|---|
Hydrogen | H2 | 8.90 | [5] | |
Nitrogen | N2 | 17.76 | [5] | |
Oxygen | O2 | 20.64 | [6] | |
Fluorine | F2 | 23.16 | [7] | |
Chlorine | Cl2 | 13.40 | [7] | |
Substance | Molecular formula | Viscosity (μPa·s) | Notes | Ref. |
---|---|---|---|---|
Methane | CH4 | 11.13 | T = 20 °C | [8] |
Acetylene | C2H2 | 10.2 | T = 20 °C | [9] |
Ethylene | C2H4 | 10.28 | T = 20 °C | [8] |
Ethane | C2H6 | 9.27 | T = 20 °C | [8] |
Propyne | C3H4 | 8.67 | T = 20 °C | [9] |
Propene | C3H6 | 8.39 | T = 20 °C | [10] |
Propane | C3H8 | 8.18 | T = 20 °C | [8] |
Butane | C4H10 | 7.49 | T = 20 °C | [8] |
Substance | Molecular formula | Viscosity (μPa·s) | Notes | Ref. |
---|---|---|---|---|
Carbon tetrafluoride | CF4 | 17.32 | [11] | |
Fluoromethane | CH3F | 11.79 | [12] | |
Difluoromethane | CH2F2 | 12.36 | [12] | |
Fluoroform | CHF3 | 14.62 | [12] | |
Pentafluoroethane | C2HF5 | 12.94 | [12] | |
Hexafluoroethane | C2F6 | 14.00 | [12] | |
Octafluoropropane | C3F8 | 12.44 | [12] |
Substance | Molecular formula | Viscosity (μPa·s) | Notes | Ref. |
---|---|---|---|---|
Air | 18.46 | [6] | ||
Ammonia | NH3 | 10.07 | [13] | |
Nitrogen trifluoride | NF3 | 17.11 | T = 26.85 °C | [14] |
Boron trichloride | BCl3 | 12.3 | Theoretical estimate at T = 26.85 °C; estimated uncertainty of 10% | [14] |
Carbon dioxide | CO2 | 14.90 | [15] | |
Carbon monoxide | CO | 17.79 | [16] | |
Hydrogen sulfide | H2S | 12.34 | [17] | |
Nitric oxide | NO | 18.90 | [7] | |
Nitrous oxide | N2O | 14.90 | [18] | |
Sulfur dioxide | SO2 | 12.82 | [10] | |
Sulfur hexafluoride | SF6 | 15.23 | [5] | |
Molybdenum hexafluoride | MoF6 | 14.5 | Theoretical estimates at T = 26.85 °C | [19] |
Tungsten hexafluoride | WF6 | 17.1 | ||
Uranium hexafluoride | UF6 | 17.4 |
Substances composed of longer molecules tend to have larger viscosities due to the increased contact of molecules across layers of flow. [20] This effect can be observed for the n-alkanes and 1-chloroalkanes tabulated below. More dramatically, a long-chain hydrocarbon like squalene (C30H62) has a viscosity an order of magnitude larger than the shorter n-alkanes (roughly 31 mPa·s at 25 °C). This is also the reason oils tend to be highly viscous, since they are usually composed of long-chain hydrocarbons.
Substance | Molecular formula | Viscosity (mPa·s) | Notes | Ref. |
---|---|---|---|---|
Pentane | C5H12 | 0.224 | [21] | |
Hexane | C6H14 | 0.295 | [22] | |
Heptane | C7H16 | 0.389 | [22] | |
Octane | C8H18 | 0.509 | [22] | |
Nonane | C9H20 | 0.665 | [21] | |
Decane | C10H22 | 0.850 | [22] | |
Undecane | C11H24 | 1.098 | [21] | |
Dodecane | C12H26 | 1.359 | [22] | |
Tridecane | C13H28 | 1.724 | [21] | |
Tetradecane | C14H30 | 2.078 | [22] | |
Pentadecane | C15H32 | 2.82 | T = 20 °C | [23] |
Hexadecane | C16H34 | 3.03 | [21] | |
Heptadecane | C17H36 | 4.21 | T = 20 °C | [24] |
Substance | Molecular formula | Viscosity (mPa·s) | Notes | Ref. |
---|---|---|---|---|
Chlorobutane | C4H9Cl | 0.4261 | [25] | |
Chlorohexane | C6H11Cl | 0.6945 | ||
Chlorooctane | C8H17Cl | 1.128 | ||
Chlorodecane | C10H21Cl | 1.772 | ||
Chlorododecane | C12H25Cl | 2.668 | ||
Chlorotetradecane | C14H29Cl | 3.875 | ||
Chlorohexadecane | C16H33Cl | 5.421 | ||
Chlorooctadecane | C18H37Cl | 7.385 | Supercooled liquid |
Substance | Molecular formula | Viscosity (mPa·s) | Notes | Ref. |
---|---|---|---|---|
Dichloromethane | CH2Cl2 | 0.401 | [26] | |
Trichloromethane (chloroform) | CHCl3 | 0.52 | [10] | |
Tribromomethane (bromoform) | CHBr3 | 1.89 | [27] | |
Carbon tetrachloride | CCl4 | 0.86 | [27] | |
Trichloroethylene | C2HCl3 | 0.532 | [28] | |
Tetrachloroethylene | C2Cl4 | 0.798 | T = 30 °C | [28] |
Chlorobenzene | C6H5Cl | 0.773 | [29] | |
Bromobenzene | C6H5Br | 1.080 | [29] | |
1-Bromodecane | C10H21Br | 3.373 | [30] |
Substance | Molecular formula | Viscosity (mPa·s) | Notes | Ref. |
---|---|---|---|---|
2-Pentene | C5H10 | 0.201 | [31] | |
1-Hexene | C6H12 | 0.271 | [32] | |
1-Heptene | C7H14 | 0.362 | [32] | |
1-Octene | C8H16 | 0.506 | T = 20 °C | [31] |
2-Octene | C8H16 | 0.506 | T = 20 °C | [31] |
n-Decene | C10H20 | 0.828 | T = 20 °C | [31] |
Substance | Molecular formula | Viscosity (mPa·s) | Notes | Ref. |
---|---|---|---|---|
Acetic acid | C2H4O2 | 1.056 | [21] | |
Acetone | C3H6O | 0.302 | [33] | |
Benzene | C6H6 | 0.604 | [21] | |
Bromine | Br2 | 0.944 | [21] | |
Ethanol | C2H6O | 1.074 | [21] | |
Glycerol | C3H8O3 | 1412 | [34] | |
Hydrazine | H4N2 | 0.876 | [21] | |
Iodine pentafluoride | IF5 | 2.111 | [35] | |
Mercury | Hg | 1.526 | [21] | |
Methanol | CH4O | 0.553 | [36] | |
1-Propanol (propyl alcohol) | C3H8O | 1.945 | [37] | |
2-Propanol (isopropyl alcohol) | C3H8O | 2.052 | [37] | |
Squalane | C30H62 | 31.123 | [38] | |
Water | H2O | 1.0016 | T = 20 °C, standard pressure | [21] |
The viscosity of an aqueous solution can either increase or decrease with concentration depending on the solute and the range of concentration. For instance, the table below shows that viscosity increases monotonically with concentration for sodium chloride and calcium chloride, but decreases for potassium iodide and cesium chloride (the latter up to 30% mass percentage, after which viscosity increases).
The increase in viscosity for sucrose solutions is particularly dramatic, and explains in part the common experience of sugar water being "sticky".
Table: Viscosities (in mPa·s) of aqueous solutions at T = 20 °C for various solutes and mass percentages [21] | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Solute | mass percentage = 1% | 2% | 3% | 4% | 5% | 10% | 15% | 20% | 30% | 40% | 50% | 60% | 70% |
Sodium chloride (NaCl) | 1.020 | 1.036 | 1.052 | 1.068 | 1.085 | 1.193 | 1.352 | 1.557 | |||||
Calcium chloride (CaCl2) | 1.028 | 1.050 | 1.078 | 1.110 | 1.143 | 1.319 | 1.564 | 1.930 | 3.467 | 8.997 | |||
Potassium iodide (KI) | 0.997 | 0.991 | 0.986 | 0.981 | 0.976 | 0.946 | 0.925 | 0.910 | 0.892 | 0.897 | |||
Cesium chloride (CsCl) | 0.997 | 0.992 | 0.988 | 0.984 | 0.980 | 0.966 | 0.953 | 0.939 | 0.922 | 0.934 | 0.981 | 1.120 | |
Sucrose (C12H22O11) | 1.028 | 1.055 | 1.084 | 1.114 | 1.146 | 1.336 | 1.592 | 1.945 | 3.187 | 6.162 | 15.431 | 58.487 | 481.561 |
Substance | Viscosity (mPa·s) | Temperature (°C) | Reference |
---|---|---|---|
Whole milk | 2.12 | 20 | [39] |
Blood | 2 - 9 | 37 | [40] |
Olive oil | 56.2 | 26 | [39] |
Canola oil | 46.2 | 30 | [39] |
Sunflower oil | 48.8 | 26 | [39] |
Honey | 2000-10,000 | 20 | [41] |
Ketchup [a] | 5000-20,000 | 25 | [42] |
Peanut butter [a] | 104-106 | [43] | |
Pitch | 2.3×1011 | 10-30 (variable) | [44] |
All values are given at 1 bar (approximately equal to atmospheric pressure).
Substance | Chemical formula | Temperature (K) | Viscosity (μPa·s) |
---|---|---|---|
Air | 100 | 7.1 | |
200 | 13.3 | ||
300 | 18.5 | ||
400 | 23.1 | ||
500 | 27.1 | ||
600 | 30.8 | ||
Ammonia | NH3 | 300 | 10.2 |
400 | 14.0 | ||
500 | 17.9 | ||
600 | 21.7 | ||
Carbon dioxide | CO2 | 200 | 10.1 |
300 | 15.0 | ||
400 | 19.7 | ||
500 | 24.0 | ||
600 | 28.0 | ||
Helium | He | 100 | 9.6 |
200 | 15.1 | ||
300 | 19.9 | ||
400 | 24.3 | ||
500 | 28.3 | ||
600 | 32.2 | ||
Water vapor | H2O | 380 | 12.498 |
400 | 13.278 | ||
450 | 15.267 | ||
500 | 17.299 | ||
550 | 19.356 | ||
600 | 21.425 | ||
650 | 23.496 | ||
700 | 25.562 | ||
750 | 27.617 | ||
800 | 29.657 | ||
900 | 33.680 | ||
1000 | 37.615 | ||
1100 | 41.453 | ||
1200 | 45.192 |
Substance | Chemical formula | Temperature (°C) | Viscosity (mPa·s) |
---|---|---|---|
Mercury [45] [46] | Hg | -30 | 1.958 |
-20 | 1.856 | ||
-10 | 1.766 | ||
0 | 1.686 | ||
10 | 1.615 | ||
20 | 1.552 | ||
25 | 1.526 | ||
30 | 1.495 | ||
50 | 1.402 | ||
75 | 1.312 | ||
100 | 1.245 | ||
126.85 | 1.187 | ||
226.85 | 1.020 | ||
326.85 | 0.921 | ||
Ethanol | C2H6O | -25 | 3.26 |
0 | 1.786 | ||
25 | 1.074 | ||
50 | 0.694 | ||
75 | 0.476 | ||
Bromine | Br2 | 0 | 1.252 |
25 | 0.944 | ||
50 | 0.746 | ||
Water | H2O | 0.01 | 1.7911 |
10 | 1.3059 | ||
20 | 1.0016 | ||
25 | 0.89002 | ||
30 | 0.79722 | ||
40 | 0.65273 | ||
50 | 0.54652 | ||
60 | 0.46603 | ||
70 | 0.40355 | ||
80 | 0.35405 | ||
90 | 0.31417 | ||
99.606 | 0.28275 | ||
Glycerol | C3H8O3 | 25 | 934 |
50 | 152 | ||
75 | 39.8 | ||
100 | 14.76 | ||
Aluminum | Al | 700 | 1.24 |
800 | 1.04 | ||
900 | 0.90 | ||
Gold | Au | 1100 | 5.130 |
1200 | 4.640 | ||
1300 | 4.240 | ||
Copper | Cu | 1100 | 3.92 |
1200 | 3.34 | ||
1300 | 2.91 | ||
1400 | 2.58 | ||
1500 | 2.31 | ||
1600 | 2.10 | ||
1700 | 1.92 | ||
Silver | Ag | 1300 | 3.75 |
1400 | 3.27 | ||
1500 | 2.91 | ||
Iron | Fe | 1600 | 5.22 |
1700 | 4.41 | ||
1800 | 3.79 | ||
1900 | 3.31 | ||
2000 | 2.92 | ||
2100 | 2.60 |
In the following table, the temperature is given in kelvins.
Substance | Chemical formula | Temperature (K) | Viscosity (mPa·s) |
---|---|---|---|
Gallium [46] | Ga | 400 | 1.158 |
500 | 0.915 | ||
600 | 0.783 | ||
700 | 0.700 | ||
800 | 0.643 | ||
Zinc [46] | Zn | 700 | 3.737 |
800 | 2.883 | ||
900 | 2.356 | ||
1000 | 2.005 | ||
1100 | 1.756 | ||
Cadmium [46] | Cd | 600 | 2.708 |
700 | 2.043 | ||
800 | 1.654 | ||
900 | 1.403 |
Substance | Viscosity (Pa·s) | Temperature (°C) |
---|---|---|
granite [47] | 3×1019 - 6×1019 | 25 |
asthenosphere [48] | 7.0×1019 | 900 |
upper mantle [48] | 7×1020 – 1×1021 | 1300–3000 |
lower mantle [ citation needed ] | 1×1021 – 2×1021 | 3000–4000 |
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7H
16, more precisely CH
3–CH(CH
3)–CH(CH
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3 replacing hydrogen atoms on carbon atoms 2 and 3. It is an alkane, a fully saturated hydrocarbon; specifically, one of the isomers of heptane.
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