An alternative reaction path is the route of lower activation energy that a catalyst provides, along which a larger fraction of collisions is effective.
An alternative reaction path is the route of lower activation energy that a catalyst provides, along which a larger fraction of collisions is effective. Malay: laluan tindak balas alternatif · Chinese: 替代反应路径.
Reactants can turn into products by more than one route, and each route has its own activation energy, its own energy barrier. A positive catalyst works by opening a new route whose barrier is lower than the original one. Because this alternative path needs less energy to get started, a greater fraction of the colliding particles now has enough energy to react. The frequency of effective collisions rises, and so the rate increases, even though the temperature and the amounts of reactant are unchanged.
Example. In the decomposition of hydrogen peroxide, the uncatalysed reaction has a fairly high activation energy and is slow. Adding manganese(IV) oxide provides an alternative path with a lower activation energy, so the peroxide breaks down into water and oxygen much faster. On an energy profile diagram this is drawn as a second curve with a lower peak between the same reactant and product levels.
Confusion to avoid. Do not say the catalyst lowers the activation energy of the original path; the original barrier is not changed. Instead the catalyst provides a different path that already has a lower barrier. Also, the alternative path does not change the reactant or product energy levels, so the overall energy change of the reaction stays the same.
The alternative reaction path is the exact mechanism by which a catalyst speeds a reaction up, so it ties the catalyst directly to activation energy and the energy profile diagram, a chain that SPM Chemistry tests together.
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