Collision Theory and Reaction Rate PowerPoint
- 2. Chemical Reactions Chemical reactions vary widely in the speeds with which they occur. ➢ Some reactions occur very quickly. If a lighted match is brought in contact with lighter fluid or another flammable liquid, it erupts into flame instantly and burns fast. ➢ Other reactions occur very slowly. A container of milk in the refrigerator will be good to drink for weeks before it begins to turn sour. ➢ Millions of years are required for dead plants under Earth’s surface to accumulate and eventually turn into fossil fuels such as coal and oil.
- 3. What is Collision Theory? - Collision theory explains how chemical reactions occur and why reaction rates differ. - It focuses on the collision between reacting particles as the driving force behind reactions. - Proposed by Max Trautz & William Lewis
- 4. Key Concepts - Reactant particles must collide with enough energy to overcome the activation energy barrier. - Collisions must occur with proper orientation for the reaction to proceed. - Not all collisions result in a reaction; only those with enough activation energy and correct orientation are successful.
- 5. What is Activation Energy The activation energy for a reaction is the minimum energy that colliding particles must have in order to undergo a reaction.
- 6. A low activation energy means that a lot of the particles will collide with enough energy to react. The reaction will be fast. A high activation energy means that far fewer particles will collide with enough energy. The reaction will be slow.
- 7. So what’s correct orientation? Orientation: the relative position or direction of something. Example: CO + NO2 -> CO2 + NO
- 9. And another one :)
- 10. Reaction Rate The reaction rate can be determined by measuring how fast the concentration of A or B decreases, or by how fast the concentration of AB increases. - Red line - reactants - Blue line - products
- 11. Factors Affecting Reaction Rate By their nature, some reactions occur very quickly, while others are very slow. However, certain changes in the reaction conditions can have an effect on the rate of a chemical reaction. Collision theory can be utilised to explain these rate effects. Those factors are: - Temperature - Surface Area - Concentration of reactants - Pressure - Catalyst