Activation Energy
This animation follows the energy profile for both an endothermic and an exothermic reaction. Select different areas on the energy profile to view the reaction progress on a molecular level.
1)Endothermic Reaction
The animation starts with an energy profile for the reaction
NO + Cl2 NOCl + Cl
You can select four points on the energy profile (A, B, C, and D). At each point, the molecular changes occurring in the reaction will be shown below the energy profile.
[A]:As the two molecules approach each other, an attractive force begins to form between the nitrogen of NO and one of the chlorines of Cl2 (indicated by a dashed line). The bond between the chlorines begins to weaken (bond length increases).
[B]:When molecules collide, they form an activated complex -- a temporary species formed by the reactant molecules as a result of the collision before they form the product. In this reaction, the activated complex is NOCl2.
[C]:At this point, the bond between nitrogen and chlorine continues to strengthen and the bond between the two chlorines continues to weaken.
[D]:A bond has now formed between nitrogen and chlorine. The bond between the two chlorines has broken. The products of the reaction are NOCl and Cl.
2)Exothermic Reaction
The animation starts with an energy profile for the reaction
NO2 + CO NO + CO2
You can select four points on the energy profile (A, B, C, and D). At each point, the molecular changes occurring in the reaction will be shown below the energy profile.
[A]:As the two molecules approach each other, an attractive force begins to form between one of the oxygens of NO2 and the carbon of CO (indicated by a dashed line). The bond between nitrogen and oxygen of NO2 begins to weaken (bond length increases).
[B]:When molecules collide, they form an activated complex--a temporary species formed by the reactant molecules as a result of the collision before they form the product. In this reaction, the activated complex is NO2CO.
[C]:At this point, the bond between carbon and oxygen continues to strengthen and the bond
[D]:A bond has now formed between carbon and oxygen. The bond between nitrogen and oxygen has broken. The products of the reaction are NO and CO2.