Hydrogen peroxide solution slowly decomposes to form water and oxygen. The reaction is much faster when a manganese(IV) oxide catalyst is added.
2H2O2(aq)→2H2O(l)+O2(g)\mathrm{2H_{2}O_{2}(aq)} \rightarrow \mathrm{2H_{2}O(l)} + \mathrm{O_{2}(g)}2H2O2(aq)→2H2O(l)+O2(g)
The table gives energy values from the reaction profiles for this reaction with and without the catalyst.
| Point on the reaction profile | Energy / kJ |
|---|---|
| reactants | 200 |
| highest point without a catalyst | 275 |
| highest point with a catalyst | 258 |
| products | 4 |
Determine the activation energy for the reaction without a catalyst and for the reaction with a catalyst.
Determine the overall energy change for the reaction. Include a sign in your answer.
State the effect of the catalyst on the overall energy change.
Describe the reaction profile for the catalysed reaction. Refer to the energy of the reactants, the energy of the products and the activation energy.
Explain why adding the catalyst increases the rate of the reaction.
53 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.