6.84 You are given the following data: H2(g) 2H(g) - Br2(g) → 2Br(g) AH°=436.4 kJ/mol AH°=192.5 kJ/mol H2(g) + Br2(g) → 2HBr(g) AH°=-72.4 kJ/mol Calculate AH° for the reaction H(g) + Br(g) → HBr(g) -