The equation for the decomposition of hydrogen peroxide is shown. 2H2O2 -> 2H2O + O2 A sample containing 1.00 mol of hydrogen peroxide is completely decomposed. This sample releases 98.0 kJ of heat energy.

1. (a)Calculate the heat energy released when 680g of hydrogen peroxide is completely decomposed. heat energy released ................................................................ kJ[2]
2. (b)Use ideas about bond breaking and bond forming to explain why the decomposition of hydrogen peroxide is exothermic.[2]
3. (c)The energy profile diagram for the decomposition of hydrogen peroxide is shown. [Diagram shows an energy profile with reactants (2H2O2) at a higher energy level than products (2H2O + O2). The activation energy peak is labelled B, and the overall energy change from reactants to products is labelled A.] Identify the energy changes. change A ............................................................................................ change B ............................................................................................[2]
4. (d)The rate of decomposition of hot H2O2 is greater than that of cold H2O2. Use ideas about particles to explain why.[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.