Hydrogen peroxide decomposes in an exothermic reaction.
2H−O−O−H→2H−O−H+O=O\mathrm{2H-O-O-H \rightarrow 2H-O-H + O=O}2H−O−O−H→2H−O−H+O=O
Statement 1: Energy is taken in to break the O−H\mathrm{O-H}O−H and O−O\mathrm{O-O}O−O bonds in hydrogen peroxide.
Statement 2: Energy is released when the weak O−O\mathrm{O-O}O−O bond breaks, and this makes the reaction exothermic.
Statement 3: More energy is released making the O−H\mathrm{O-H}O−H and O=O\mathrm{O=O}O=O bonds than is taken in breaking the O−H\mathrm{O-H}O−H and O−O\mathrm{O-O}O−O bonds.
Which statements are correct?
1 only
2 and 3 only
1, 2 and 3
1 and 3 only
94 exam-style questions on Edexcel GCSE Chemistry 8.2 Heat energy changes in chemical reactions, covering 8.2.1 Exothermic and endothermic changes, 8.2.2 Bond breaking, bond making and overall energy change, 8.2.3 Calculating energy change from bond energies, and 8.2.4 Activation energy and reaction profiles. Each one has a worked solution and a mark scheme showing where the marks go.