1. Reaction Kinetics and Equilibrium
How compounds react with each other

2. Collision Theory
A reaction is most likely to occur if reactant particles collide with the proper energy and orientation

3. Reaction Rate Affecting Factors
Nature of Reactants
Concentration
Surface Area
Temperature
Presence of a Catalyst
Pressure for Gases

4. Nature of Reactants Factors that contribute to reaction rate:
- Electronegativity
- Ionization energy
- Atomic Radius.

5. Bonding on Rate of Reaction
Covalent bonds require more energy during collisions due to a greater number of bonds needed to be broken and reformed.
Ionic Bonds are faster to react and require less energy during a collision.

6. Concentration
We measure concentration by the number of moles there are in a L of solution (Molarity).
More moles = more collisions
Ex: Burning paper. When the oxygen concentration is low the paper burns slowly. Raise the amount of oxygen the paper burns faster.

7. Surface Area
The larger the surface area the easier it is to react because there is more chances for collision.

8. Temperature The average kinetic energy of molecules in a compound.
The more molecules move the higher the temperature.
Higher temperature results in more collisions

9. Presence of a Catalyst
A substance whose presence increases the rate of a chemical reaction.
Catalysts change (decrease) the activation energy which increases the rate of reaction

10. Activation Energy
Activation energy is the minimum energy required to initiate a reaction.
When particles collide with the right amount of activation energy it breaks the existing bond.

11. Energy Kinetic Energy (motion) – this the energy of work being done
Potential Energy (static) – the potential for something to do work
**Remember that there are many types of energy:
- electrical
- thermal
- mechanical
- electromagnetic
- nuclear

12. Endothermic vs. Exothermic Reactions
Exothermic (exit) reactions give off heat energy during a chemical reaction
Endothermic (enter) reactions absorb heat energy during a chemical reaction

13. Potential Energy Diagram
Used to show the energy released or stored in endothermic and exothermic reactions

14. Reading Energy Diagrams
THE Y AXIS – Potential energy of the reaction
THE X AXIS – Reaction as it takes place over time
CURVE – Represents the potential energy at each step of a chemical reaction

15. Reading Energy Diagrams
ENTHALPY – Heat of reaction
SUBTRACT THE VALUES ON THE Y AXIS, FINAL – INITIAL
EXOTHERMIC REACTION – energy given off during a reaction
LOOK AT THE CURVE AND SEE IF IT ENDS AT A LOWER VALUE

16. Reading Energy Diagrams
ENDOTHERMIC – energy is absorbed during a reaction
LOOK AT THE CURVE AND SEE IF IT ENDS AT A HIGHER VALUE
ACTIVATION ENERGY – The amount of energy needed to reach the peak of the curve
SUBSTRACT THE ENERGY AT THE PEAK OF THE CURVE FROM THE INITIAL ENERGY

17. Equilibrium
The rate at which the products are formed is at the same rate that the reactants are formed.
Three Types of equilibrium:
Phase Equilibrium
Solution Equilibrium
Chemical Equilibrium

18. Rate of Reaction at Equilibrium
As products are formed the amount of reactants decreases. We can find the rate of reaction by the equation:
Δ [M products] = Δ [M reactants]
Δ Time Δ Time

19. Equilibrium Constant Keq
Expressed as a numerical value, relates the amount of reactants to products at equilibrium
Keq = [products]n
[reactants]n
aA + bB cC + dD
Keq = [C]c [D]d
[A]a [B]b

20. Heat of Reaction (Enthalpy)
Heat of Reaction – energy stored or released during a reaction.
ΔH = H Products – H Reactants

21. Known Heat of Reactions (ΔH)
Table I lists heats of reactions at STP.
ΔH = “-” value for exothermic reactions
ΔH = “+” value for endothermic reactions
Heat of formation (ΔHf)= amount of energy released when a mole of substance is formed from it’s elements

22. Entropy
The measure of the randomness or disorder of a system’s energy.
The greater the randomness the greater the entropy.

23. Entropy of Substances
As a substance goes from solid to liquid to gas, entropy increases.
Systems in nature tend to undergo changes toward low energy and high entropy

24. Spontaneous Reactions
Two factors help determine if a reaction will react spontaneously:
Decrease in Enthalpy ΔH (potential energy) exothermic reaction
Increase in Entropy ΔS (random release in energy) as it goes from a solid – liquid – gas

25. Gibbs Free Energy
For a reaction to be spontaneous the sign of ΔG (Gibbs Free Energy) must be negative.
ΔG = ΔH – TΔS
ΔH = Change in enthalpy
T = Temperature in Kelvin
ΔS = Change in entropy