Question

consider the reaction 2O3<-->3O2, hrxn=-285.4 kj/mol. in which direction will the reaction shift when the following stresses are applied?

-Add ozine to the system

-Add a catalyst

Answer 1

1. According to Le chatelier's principle for a reversible reaction we can predict that if we increase the amount of reactant i.e. Ozone here, the product formation or the forward reaction(production of O₂) will be facilitated. Thus reaction will shift towards right hand side i.e. forward reaction.
2. Catalysts are chemical substances that alters the rate of the reaction without itself undergoing any permanent change. Basically addition of catalyst makes the reaction occur in a different pathway, where the activation energy is less, thus the reaction rate increases. So addition of catalyst to a reversible reaction increases both the forward rate as well as the backward rate, thus reaching to a equilibrium much faster. So catalyst will not shift the reaction to a specific direction, instead it will help the reaction to reach its equilibrium at faster rate.