Discussion Time

A should tell B and B should rephrase I know how to 1. A.????? B. Do you mean A.????? B. Do you mean A.????? B. Do you mean A.????? B. Do you mean A.????? B. Do you mean

A Tell B and B rephrase 1. Rate of reaction formula 2. units 3. Increase and decrease of reactant and product amount 4. Convert time units 5. 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?

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 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 collisions Reaction 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 H 2 O 2, food colouring, and dishwashing detergent. The O 2 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 increasesthe 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 H 2 and O 2 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 2007R. Mulenga Which reaction is faster? Why? COOL PARTICLES HOT PARTICLES

Rate of Reaction – Collision Theory 2007R. Mulenga Which reaction is faster? Why? DILUTE SOLUTION CONCENTRATED SOLUTION

Rate of Reaction – Collision Theory 2007R. Mulenga Which reaction is faster? Why? BIG PIECE (small surface area) SMALL PIECES (large surface area)

Explain each Scenario Using the Collision Theory 3.H 2 O 2 decomposes very slowly at room temperature. 2H 2 O 2(aq) → O 2(g) + 2H 2 O (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 2007R. Mulenga TRUEFALSE TRUE OR FALSE Collision theory helps us to explain rates of reaction

Rate of Reaction – Collision Theory 2007R. Mulenga TRUEFALSE TRUE OR FALSE Reaction rates depend on temperature

Rate of Reaction – Collision Theory 2007R. Mulenga TRUEFALSE TRUE OR FALSE Reactions will speed up if they are heated

Rate of Reaction – Collision Theory 2007R. Mulenga TRUEFALSE TRUE OR FALSE Dilute solutions of reactants will react faster than concentrated solutions of reactants

Rate of Reaction – Collision Theory 2007R. Mulenga TRUEFALSE TRUE OR FALSE Reactions slow down if they are diluted

Rate of Reaction – Collision Theory 2007R. Mulenga TRUEFALSE TRUE OR FALSE A powdered reactant will react slower than a solid lump of reactant

Rate of Reaction – Collision Theory 2007R. Mulenga TRUEFALSE TRUE OR FALSE A larger surface area decreases the number of useful collisions

Rate of Reaction – Collision Theory 2007R. Mulenga TRUEFALSE TRUE OR FALSE When particles collide they always react

Rate of Reaction – Collision Theory 2007R. 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