COLLISION THEORY Flashcards
Kinetic Molecular Theory (now “Collision Theory”)
- gases consist of a large number of particles that move randomly
- size of gas particles are negligible. Although the particles have mass, their volumes are negligible
- collisions between the gas particles are completely elastic (no net loss of energy)
- the average kinetic energy of the particles is proportional to the absolute temperature in Kelvin
Particles must meet what requirements in order to react?
- they must collide with each other
- the collision must occur with enough energy (particles must have enough initial KE) to overcome the activation barrier of the reaction
- the collision must occur with the correct geometry (alignment)
Activation energy
the minimum amount of energy required for a reaction to take place (kJ/mol)
How does concentration of a solution or pressure of a gas affect the reaction?
Affects the COLLISIONS (therefore reaction rate)
Increase in concentration results in increase in rate.
As concentration increases, the frequency of collisions increase, therefore frequency of successful collisions increase.
How does the surface area affect the reaction?
Affects the COLLISIONS (therefore reaction rate)
Increase in surface area increases the number of particles therefore increases the number of probably successful collisions.
How does the temperature affect the reaction?
Affects the COLLISIONS (therefore reaction rate)
IN GENERAL: for every 10 deg.Celc increase, rate of reaction approximately doubles
How do catalysts affect the reaction?
Affects the proportion of particles with sufficient activation energy
Provides an alternate pathway with a lower Ea. They DO NOT lower the activation energy of a reaction.
Both forward and reverse rates increase.
Homogeneous catalyst
Same physical state as the reactants
Heterogenous catalyst
Different physical states as the reactants
