• Exothermic reactions: lose energy and involve bonds breaking; ΔH is negative
• Endothermic reactions: gain energy and involve bonds forming; ΔH is positive
Ozone, O3(g), is a form of elemental oxygen that is important in the absorption of ultraviolet radiation in the stratosphere. It decomposes to O2(g) at room temperature and pressure according to the following reaction: 2 O3(g) → 3 O2(g), ΔH = –284.6 kJ
Which has the higher enthalpy under these conditions, 2 O3 (g) or 3 O2 (g)?