... Reactions often occur only above 400 °C, eg, with H 2 O, Al 2 O 3 , and countless other compounds ... Table 1. Some Physical Properties of the Hexafluorides, Except XeF 6 ; The Volume Per Molecule Data Refer to the ... vol/molecule [10 6 pm 3 ], 91.0(75 K)(41), 97.8(41), 102.4(40). ...