Catalyst notes for Chem 101L~
Catalyst is a substance that speeds up a chemical reaction without being changed permanently itself
Our bodies have reactions within themselves that use catalyst that are called enzymes. Catalyst speed up chemical reactions by providing an different pathway for reactants and products that doesn't require as much reaction energy.
O3(g)+ O(g)>2Oz(g)
This is a reaction in the stratosphere between ozone molecules and oxygen atoms is a great example. Activation energy is 17 kJ /mole at 298K. Only one in every thousand collisions have enough kinetic energy to form activated complex or to proceed to products. The collision must be orientated correctly to break bonds and make them at the same time.
Chlorine will catalyze this reaction in 2 steps
O3(g)+CI(g) > CIO(g) + Oz(g)
O(g) + CIO(g) > Cl(g) + Oz(g)
Net reaction Os(g) + O(g) >CI 2Oz(g)
The Chlorine atoms provide the secondary pathway for the reaction
Catalysts have a property called selectivity, they can direct a reaction to increase the amount of desired product and reduce the amount of unwanted byproducts. They can produce completely new material