Collision theory Flashcards
What is kinetics?
the study of the factors that affect rates of chemical reactions
What is necessary for collisions to take place between particles?
particles must collide with sufficient energy to break bonds
the collision must take place between the parts of the molecule that are going to react together (orientation)
What increases the rate of reaction?
- increasing temperatures - increases energy and number of collisions increasing
- concentration -more particles in a given volume, particles are more likely to collide
- increasing pressure - smaller volume increasing
- surface area of solid reactants - more particles are available to collide with fluids, more reaction sites catalyst
- increase collision freq and surface contact
What is the MINIMUM energy to start breaking bonds?
activation energy,
symbol Ea
shown as the distance between the reactants and the transition state on a enthalpy diagram
What is the transition state?
the area at the top of the curve on a enthalpy diagram
also known as activated complex
some bonds are in the process of being made and some bonds are being broken
What does the enthalpy diagram look like for endothermic and exothermic?
endo: products have more energy than reactants
Explain theffect of lowering the temperature would have on the rate of reaction?
(decrease)
- fewer particles have energy greater than or equal to the activation energy
- fewer successful collision in a given time
Explain the effect of lowering the number of reactants has on the rate of reaction?
(decreases)
- particles are spread further apart
- fewer collision between particles, so fewer successful collisions
OH- was first order when 0.02M
increased to 2.0 M, now zero order
[A] remain 1st order at 0.02 M
suggest why?
- large excess
- [OH-] effectively constant
- [A] is limiting factor
