Kinetics and Equilibrium Flashcards
What is collision theory?
In order for collisions to occur there must be an effective collision
What makes an effective collision?
- Sufficient (enough) energy
- Proper orientation
Why do reactants need sufficient Kinetic energy to cause reactions?
It increases the rate of the reaction and the number of collisions!
What are the factors that affect reaction rate?
Temperature Pressure Concentration Surface Area Nature of Reactants Catalysts
How does Temperature affect reaction rate?
-Molecules move faster causing more collisions
How does Concentration affect reaction rate?
-More molecules (high concentration) causes increased reaction rate
How does Surface Area affect reaction rate?
Having more surface area to gain sufficient energy and have more collisions
What does a catalyst do?
Increases reaction rate by lowering activation energy!
How does Pressure affect reaction rate?
- ONLY FOR GASES!*
- Compressed particles lead to less space and more collisions
How do Nature of Reactants affect reaction rate?
- Fastest reaction are ionic aqueous solutions
- Slowest reactions are molecular which take longer to separate
What is activation energy?
The energy needed to start a reaction
What is heat of reaction also called?
ENTHALPY
Exothermic:
- Heat Released
- Products LESS energy than reactants
- Heat of reaction is NEGATIVE
Endothermic:
- Heat absorbed
- Products MORE energy than reactants
- Heat of reaction is POSITIVE
What does a system want:
Order or Disorder?
Systems lean towards DISORDER and lower energy!
Called ENTROPY
Order of phases from highest entropy to lowest entropy:
G ——> L ——> S
Which reactions are more spontaneous, Exothermic or Endothermic?
Exothermic reactions are more spontaneous!
The higher the energy content, the LESS STABLE a compound
Endothermic reactions → Less stability
Exothermic reactions → More stability
Negative ΔH:
Amount of Energy RELEASED in KJ
Positive ΔH:
Amount of energy ABSORBED in KJ
What is equilibrium?
When the rate of the forward reaction EQUALS the rate of the reverse reaction
If you’re adjusting temp, conc, shifting, etc. are you in equilibrium?
NO!
At Equilibrium:
All observable properties are CONSTANT
Amount of reactants and products are CONSTANT
Equilibrium only occurs in a CLOSED system
What are the 3 types of Equilibrium?
- Phase Equilibrium (phase changes)
- Solution Equilibrium (w dissolved & undissolved solute)
- Chemical Equilibrium (forward = reverse)
Predict 2 conditions that might cause a system in equilibrium, to suddenly no longer be in equilibrium
-Increase temp
-Increase Concentration
-Increase Pressure
(Or decrease)
What is Le Chatelier’s Principle?
If stress is added to a system at equilibrium, the equilibrium will shift in a way to RELIEVE the stress
If a substance’s concentration is increased:
SHIFT AWAY from itself
If a substance’s concentration is decreased:
SHIFT TOWARDS itself
If temperature is increased:
Shift away from heat
If temperature is decreased:
Shift towards the heat
If pressure is increased on GASES:
Shift towards less moles of gas
If pressure is decreased on GASES:
Shift towards more moles of gas
What is a successful collision?
One that causes a reaction!
Determining Enthalpy (Heat of Reaction)
H products - H reactants
