Using average bond enthalpy values estimate ΔH (kJ/mol) for the following gas phase r Using average bond enthalpy values estimate ΔH (kJ/mol) for the following gas phase reaction. CH2=CH2 + Br2 --> CH2BrCH2Br I followed this topic: http://answers.yahoo.com/question/index?qid=20080306194402AAtIc63 and I got the wrong answer. I came up with 129 which is wrong. Here is my work : C-H = 4x416 = 1664 C=C = 1x598 = 598 Br-Br = 2x193 = 386 1664+598+386 = 2648 C-H = 4x416 = 1664 c-Br = 3x285 = 855 1664+2519 = 2519 2648-2519 = 129 (which is wrong.) Please Help Me! Thank you!