discussion time. a should tell b and b should rephrase i know how to 1. a.????? b. do you mean...

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