The enthalpies of formation of iodine pentafluoride and iodine heptafluoride

Abstract The energy of combustion of iodine in fluorine was measured in a bomb calorimeter and the standard enthalpy of formation of liquid iodine pentafluoride, Δ H f o (IF 5 , 1, 298·15 K), was calculated to be −(210·8 1 ± 0·3 9 ) kcal/mole. The combustion products contained variable quantities of gaseous iodine heptafluoride (IF 7 ) in addition to IF 5 . A linear least squares analysis of the standard energy of combustion of iodine as a function of the ratio of IF 7 to IF 5 enabled a value of −(229·8 0 ± 0·5 4 ) kcal/mole to be deduced for Δ H f o (IF 7 , g, 298·15 K).