Question

Why do different reactions occur at different rates?

Answer 1

1. Nature of reactants: Ionic reactions occur faster than covalent reactions because bond breaking in covalent molecules requires more energy.
2. Activation energy: Reactions with low activation energy proceed faster; high E_a slows down the reaction.
3. Concentration of reactants: Higher concentration increases the frequency of collisions, thus increasing the rate.
4. Temperature: Higher temperature increases kinetic energy and the number of effective collisions, speeding up the reaction.
5. Catalyst presence: Catalysts lower activation energy, increasing the rate without being consumed.
6. Physical state and surface area: Finely divided solids react faster than large pieces due to greater surface area.
7. Nature of medium: Some reactions are faster in aqueous medium, others in non-polar solvents, depending on solubility and interaction.