Transcript Collision Theory - iannonechem.com

Kinetics
Lesson 3
Collision Theory
The Collision Theory
Link to Simulation of Molecular Motion
1.
Matter is moving particles.
2.
Temperature increases- particles move faster
-more collisions
-more collision energy.
3.
Chemical reactions
-bonds break
-new bonds form
4.
Collisions provide the energy.
Collision Theory
You need a collision to have a reaction.
Collisions provide the energy required to break bonds.
Most collisions are not successful
Collision Theory
A successful collision requires:
1.
Favourable Geometry
products
Poor Geometry
no products
2.
Sufficient Energy to break the chemical bonds
Activation energy is the minimum amount of energy required for a successful
collision.
The Collision Theory can be used to explain how the rate of a reaction can be changed.
Reaction rates can increase due to
1.
More collisions
2.
Harder collisions- greater collision energy
3.
Lower activation energy or Ea- low energy collisions are more effective.
And that’s it!
The Collision Theory can be used to explain how the rate of a reaction can be changed.
1.
Increasing the temperature increases the rate because there are:
More collisions
Harder collisions
2.
Increasing the reactant concentration increases the rate because there are:
More frequent collisions
The Collision Theory can be used to explain how the rate of a reaction can be
changed.
3.
Adding a catalyst
Lowers the activation energy or Ea- allowing low energy collisions to be successful
The catalyst KI is added to H2O2, food colouring, and dishwashing detergent. The O2
produced makes foam.
Movie
The Collision Theory can be used to explain how the rate of a reaction can be
changed.
4.
Changing the nature of the reactant for a more reactive chemical increases
the rate
Lower activation energy or Ea- allowing low energy collisions to be successful
The Collision Theory can be used to explain how the rate of a reaction can be
changed.
5.
Increasing the surface area of a solid reactant increases the rate because:
More frequent collisions
Explain each Scenario Using the Collision Theory
1.
A balloon full of H2 and O2 do not react at room temperature.
Ea is too high for the room temperature collisions
A small spark ignites causes an explosion.
The spark provides the Ea and it explodes because it is exothermic
Explain each Scenario Using the Collision Theory
2.
A candle does not burn at room temperature
Ea is too high for the room temperature collisions
A match causes the candle to burn
The match provides the Ea
The candle continues to burn
It burns because it is exothermic
Explain each Scenario Using the Collision Theory
3.
H2O2 decomposes very slowly at room temperature.
2H2O2(aq) → O2(g) + 2H2O(l)
KI increases the reaction rate dramatically.
KI is a catalyst as it is not a reactant and it speeds up the rate.
Lowers the Ea- allows low energy collisions to be successful
Describe and Graph the Relationship between the Following
Ea and the rate
Decreasing the Ea increases the rate- inverse.
Rate
Ea
Describe and Graph the Relationship between the Following
Temperature and the rate
Increasing the temperature increases the rate- direct.
Rate
Temp
Describe and Graph the Relationship between the Following
Concentration and the rate
Increasing the concentration increases the rate- direct.
Rate
Conc
Describe and Graph the Relationship between the Following
Ea and the temperature
The only way to change the Ea is by adding a catalyst!
No relationship!
Temp
Ea
Which factors increase the percentage of successful collisions?
I.
Increasing temperature
II.
Increasing concentration
III.
Increasing surface area
IV.
Adding a catalyst