discussion time. a should tell b and b should rephrase i know how to 1. a.????? b. do you mean...
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Discussion Time
A should tell B and B should rephrase I know how to 1. A .????? B. Do you mean --------- 2. A .????? B. Do you mean ---------3. A .????? B. Do you mean ---------4. A .????? B. Do you mean ---------5. A .????? B. Do you mean ---------
A Tell B and B rephrase 1. Rate of reaction formula2. units3. Increase and decrease of reactant and product amount4. Convert time units5. Convert mass to mole, volume to mole 6. How to draw graph, dependent and independent variables
A Tell B and B rephrase 1.What type of reactions are fastest?2.Homo– hetro- 3.What factors can speed up reactions?4.What factors are good for both homo- and hetero– and what factors are only good for homo---5.How collisions are affected by these factors?
KineticsLesson 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
Most collisions are not successful
Collisions provide the energy required to break bonds.
You need a collision to have a reaction.
Collision Theory
Most collisions (dates) are not successful
Collisions provide the energy required to break bonds.
You need a collision to have a reaction.
Collision Theory
Most collisions (dates) are not successful
Collisions provide the energy required to break bonds.
You need a collision to have a reaction.
Collision Theory
products no products
1. Favourable Geometry
A successful collision requires:
Poor Geometry
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.
And that’s it!
3. Lower activation energy or Ea- low energy collisions are more effective.
2. Harder collisions- greater collision energy
1. More collisionsReaction rates can increase due to
The Collision Theory can be used to explain how the rate of a reaction can be changed.
Harder collisions
More collisions
1. Increasing the temperature increases the rate because there are:
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.
The catalyst KI is added to H2O2, food colouring, and dishwashing detergent. The O2 produced makes foam.
Lowers the activation energy or Ea- allowing low energy collisions to be successful
3. Adding a catalyst
Movie
The Collision Theory can be used to explain how the rate of a reaction can be changed.
Lower activation energy or Ea- allowing low energy collisions to be successful
4. Changing the nature of the reactant for a more reactive chemical increases the rate
The Collision Theory can be used to explain how the rate of a reaction can be changed.
More frequent collisions
5. Increasing the surface area of a solid reactant increases the rate because:
Explain each Scenario Using the Collision Theory
The spark provides the Ea and it explodes because it is exothermic
A small spark ignites causes an explosion.
Ea is too high for the room temperature collisions
1. A balloon full of H2 and O2 do not react at room
temperature.
Explain each Scenario Using the Collision Theory
It burns because it is exothermic
The candle continues to burn
The match provides the Ea
A match causes the candle to burn
Ea is too high for the room temperature collisions
2. A candle does not burn at room temperature
Rate of Reaction – Collision Theory 2007 R. Mulenga
Which reaction is faster? Why?
COOL PARTICLES HOT PARTICLES
Rate of Reaction – Collision Theory 2007 R. Mulenga
Which reaction is faster? Why?
DILUTE SOLUTION
CONCENTRATEDSOLUTION
Rate of Reaction – Collision Theory 2007 R. Mulenga
Which reaction is faster? Why?
BIG PIECE (small surface area)
SMALL PIECES(large surface area)
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.
Lowers the Ea- allows low energy collisions to be successful
KI is a catalyst as it is not a reactant and it speeds up the rate.
Rate of Reaction – Collision Theory 2007 R. Mulenga
TRUETRUE OR FALSEFALSE
Collision theory helps us to explain rates of reaction
Rate of Reaction – Collision Theory 2007 R. Mulenga
TRUETRUE OR FALSEFALSE
Reaction rates depend on temperature
Rate of Reaction – Collision Theory 2007 R. Mulenga
TRUETRUE OR FALSEFALSE
Reactions will speed up if they are heated
Rate of Reaction – Collision Theory 2007 R. Mulenga
TRUETRUE OR FALSEFALSE
Dilute solutions of reactants will react faster than concentrated solutions of reactants
Rate of Reaction – Collision Theory 2007 R. Mulenga
TRUETRUE OR FALSEFALSE
Reactions slow down if they are diluted
Rate of Reaction – Collision Theory 2007 R. Mulenga
TRUETRUE OR FALSEFALSE
A powdered reactant will react slower than a solid lump of reactant
Rate of Reaction – Collision Theory 2007 R. Mulenga
TRUETRUE OR FALSEFALSE
A larger surface area decreases the number of useful collisions
Rate of Reaction – Collision Theory 2007 R. Mulenga
TRUETRUE OR FALSEFALSE
When particles collide they always react
Rate of Reaction – Collision Theory 2007 R. Mulenga
“Match of the Day”
Temperature
Concentration
Surface Area
There are more particles to collide
There is a bigger surface area for other particles to collide with
Particles move faster and so there are more collisions and collisions have more energy
Describe and Graph the Relationship between the Following Ea and the rate
Ea
Rate
Decreasing the Ea increases the rate- inverse.
Describe and Graph the Relationship between the Following Temperature and the rate
Temp
Rate
Increasing the temperature increases the rate- direct.
Describe and Graph the Relationship between the Following Concentration and the rate
Conc
Rate
Increasing the concentration increases the rate- direct.
Describe and Graph the Relationship between the Following Ea and the temperature
Ea
Temp
No relationship!
The only way to change the Ea is by adding a catalyst!
Which factors increase the percentage of successful collisions?
I.Increasing temperature
II.Increasing concentration
III.Increasing surface area
IV. Adding a catalyst