ENTHALPY Activation energy the activated complex and the
- Slides: 30
ENTHALPY Activation energy, the activated complex, and the effect of a catalyst
Learning Objectives • The activated complex is an unstable arrangement of atoms formed at the maximum of the potential energy barrier, during a reaction. • The activation energy is the energy required by colliding molecules to form an activated complex. • The activation energy can be calculated from potential energy diagrams. • The effect of a catalyst can be explained in terms of alternative reaction pathways with lower activation energy. • A potential energy diagram can be used to show the effect of a catalyst on activation energy.
ACTIVATION ENERGY
Energy Reactants Products Reaction Progress
Energy EA Reactants DH Products Reaction Progress
Energy Reactants DH Products Reaction Progress
Energy Reactants DH Products Reaction Progress
Energy EA Reactants DH Products Reaction Progress
Energy What happens here? EA Reactants DH Products Reaction Progress
THE ACTIVATED COMPLEX
Reactant A
Reactant A Reactant B
Activated complex
Activated complex
Activated complex
Product C
Energy Activated Complex EA Reactants A+B DH Product C Reaction Progress
THE EFFECT OF A CATALYST
Ea MOLECULAR ENERGY NUMBER OF MOLECUES WITH A PARTICULAR ENERGY
NUMBER OF MOLECUES WITH A PARTICULAR ENERGY EXTRA MOLECULES WITH SUFFICIENT ENERGY TO OVERCOME THE ENERGY BARRIER Ea MOLECULAR ENERGY
Energy Effect of catalyst Without catalyst EA Reactants DH Products Reaction Progress
Energy Effect of catalyst With catalyst Reactants DH Products Reaction Progress
Energy Effect of catalyst EA With catalyst Reactants DH Products Reaction Progress
Energy Effect of catalyst Without catalyst EA Reactants DH Products Reaction Progress
Energy Effect of catalyst EA With catalyst Reactants DH Products Reaction Progress
Energy Effect of catalyst Without catalyst EA EA With catalyst Reactants DH Products Reaction Progress