1. Energy in Rxns & Potential Energy Diagrams
Thermodynamics

2. Heat is energy that flows from…..
An area of high temperature to an area of lower temperature.

4. Why does the ice pack
feel cold?
Where does the energy flow?

5. Heat Energy and Chemical Rxns
System absorbs Energy from the surroundings (the temp of the surroundings decreases)
endothermic
System releases Energy to the surroundings (the temperature of the surroundings increases)
exothermic

6. Endothermic Rxns Where does this energy come from? The surroundings
540KJ + A + B  C + D
Where does this energy come from?
The surroundings
Where does it go?
Into the system C & D
E is a reactant
E is absorbed

7. Exothermic Rxns Where did this energy come from? The system A & B
A + B  C + D + 540KJ
Where did this energy come from?
The system A & B
Where does it go?
The surroundings
E is a product
E is released

8. Endothermic Reaction Energy of the Activated complex
(transition state)
Activation Energy
Energy of products
Enthalpy ∆H
Potential Energy (KJ)
Energy of reactants
Reaction time (s)

9. Exothermic Reaction Energy of the Activated complex (transition state)
Activation Energy
Energy (KJ) Er ∆H
Enthalpy Ep
Reaction time (s)

10. These graphs are Reversible and can be read in the forward direction  and in the reverse direction

11. In truth…. Reactions take place in a series of steps. Some steps are
endothermic and some exothermic. The can be added into an
overall. E1
Transition state
intermediate E2
Transition State
intermediate
Transition state
product E3

12. The End