A catalyst
(IIT-JEE, 1984)
Decreases the activation energy
Alters the reaction mechanism
A catalyst provides an alternative path for the reaction occurring via a different activation state.
A positive catalyst decreases the activation energy of a reaction, so that more number of molecules are able to cross the activation energy barrier and so the rate of the reaction is increased.
A negative catalyst increases the activation energy of a reaction so that lesser number of molecules are able to cross the activation energy barrier and so the rate of the reaction is decreased.