Review Article
Food Packaging Permeability Behaviour: A Report
Table 3
The most important properties of gases used in the permeability experiments.
| | Properties | N2 | CO2 | O2 |
| | Molecular diameter/cm·10−8 | 3.15 | 3.34 | 2.98 | | Mean free path/cm·10−6 | 9.29 | 6.15 | 9.93 | | Average velocity/cm s−1·10−2 | 471 | 376 | 440 | | Van der Waals constant a/bar L2 mol−2 | 1.39 | 3.59 | 1.36 | | Van der Waals constant b/L mol·10−2 | 3.91 | 4.27 | 3.18 | | Molar mass/kg kmol−1 | 28.013 | 44.01 | 31.999 | | Critical volume/cm3 mol−1 | 90.1 | 94 | 78 | | Viscosity/P | 176 | 147 | 204 | | Gas density/kg m−3 | 1.25 | 1.98 | 1.43 | | Molecular volume/cm3 mol−1 | 31.2 | 30.7 | 25.6 | | Solubilities of gases in water at different temperatures/cm3 dm−3 | 16.0 (20°C)
12.5 (40°C)
10.2 (60°C) | 878 (20°C)
530 (40°C)
360 (60°C) | 31 (20°C)
23 (40°C)
19 (60°C) | | Diffusion coefficients of gases in water at 20°C/cm2 s−1·105 | 1.64 | 1.77 | 1.8 | | Kinetic diameter/cm 10−8 | 3.64 | 3.30 | 3.46 | | Critical temperature/K | 126.2 | 304.2 | 154.8 | | Critical pressure/MPa | 3.39 | 7.39 | 5.08 | | Gas constant/kJ kg−1 K−1 | 0.2968 | 0.1889 | 0.2598 | | Effective diameter/cm 10−8 | 3.66 | 3.63 | 3.44 | | Collision diameter/cm | 3.68 | 4.00 | 3.43 | | Lennard-Jones force constant | 91.5 | 190 | 113 |
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