collision theory. use the collision theory to explain the rate of chemical reactions. include:...
TRANSCRIPT
Collision Theory
• Use the Collision Theory to explain the rate of chemical reactions.
Include: Activation energy • Draw potential energy diagrams for various
reactions. Include: exothermic, endothermic, activated complex, enthalpy
Additional KEY Termstransition state
In order for a chemical reaction to occur, the reacting particles must collide with each other.
If the particles do not collide, no reaction occurs.
The collision theory states:
1. Particles must collide with the correct orientation:
2. Particles must also collide with enough energy:
Energy required to make/break bonds in a chemical reaction.
If colliding particles do not have enough velocity (Kinetic Energy) - no reaction.
Minimum energy required to produce a chemical reaction is called the Activation Energy (EA).
Frequency of successful collisions determines the Rate of a reaction.
Activation Energy
Particles withActivation Energy
Each reaction has its own specific activation energy.
Maxwell-Boltzman Curve
At point of collision:Particles form unstable intermediate particle called the activated complex or transition state.
AC has maximum potential energy but exists for a very small time.
+
Enthalpy (H) is the heat content or total energy possessed by the particles in a system.
Energy released or absorbed in a reaction is called the change in enthalpy, ΔH, or heat of reaction.
Units of energy are Joules (J).
ΔH = Hproducts - Hreactants
- ΔH : products have less enthalpy (energy) then reactants.
Heat flows out of the system – exothermic.
+ΔH : products have more energy than reactants. Heat absorbed into the system – endothermic.
ΔH = 10 - 15ΔH = Hproducts - Hreactants
ΔH = 15 - 10ΔH = Hproducts - Hreactants
Reaction coordinate diagram or
Potential energy (PE) diagram
• Represents energy change during a reaction.
Greater activation energy - slower reaction rate - longer the reaction takes.
CH3CH2Br + OH− → CH3CH2OH + Br−
CAN YOU / HAVE YOU?
• Use the Collision Theory to explain the rate of chemical reactions.
Include: Activation energy • Draw potential energy diagrams for various
reactions. Include: exothermic, endothermic, activated complex, enthalpy
Additional KEY Termstransition state