■2.从键能估算反应热 H H H H →HC O H H H H H由 Ec=c=602,E0-H=458.8,Ec-H=411 Ec-c=345.6,Ec-o=357.7kJmo1 △rHm°=4Ec-H+1XEc=c+2XEo-H -[5 EC-H+1X Ec-c+1X Ec-o+1X Eo-H] Ec=c+Eo-H-Ec-H-Ec-c-Ec-o =602+459-411-346-358 =-54 kJ.mol-1◼ 2.从键能估算反应热 Ec=c＝602 ，EO-H＝458.8，EC-H＝411 Ec-c＝345.6，Ec-o＝357.7 kJ·mol-1 rm ＝4 EC-H +1× Ec=c +2× EO-H -[5 EC-H + 1× Ec-c + 1× Ec-o + 1× EO-H] ＝ Ec=c+ EO-H - EC-H - Ec-c- Ec-o ＝602+459-411-346-358 ＝-54 kJ·mol-1