There is no gas which follows the gas laws at the lowest temperatures, because every gas becomes liquid at a certain temperature. The laws, therefore, apply to so called ideal gases only. A gas approaches the ideal state as the pressure decreases and the temperature increases. If one carries on cooling down a gas more and more at constant pressure, the volume at t = -273.15°C will be the
V(-273.15) = V0 (1 - 273.15°C/273.15°C) = 0, under the law of Gay-Lussac. A temperature below -273.15°C is therefore not possible. Therefore the temperature of -273.15°C thus forms the point of absolute zero from which point only positive temperature values can be recorded. From this arises the scale of absolute temperature with the absolute temperatures T in degree Kelvin °K. Temperature differences in °K and °C are the same. This applies also to temperature differences in °R and °F.
Table 2.4.3.1 - Temperature Calculations
