kinetics Flashcards
define activation energy
heat energy required (per mole) for a collision between 2 particles to result in a chemical reaction
what are the 4 things that increase rate of reaction
increased surface area
increased concentration/pressure
increased temp
adding catalyst
what is the relationship between rate and surface area
Rate is proportional to solid surface area:
- More solid particles are accessible for collisions
- Collision frequency increases
- Successful collision frequency increases
what is the relationship between rate and solution concentration/gras pressure
Rate is sometimes proportional to solution concentration / gas pressure:
- More collisions per unit volume
- Collision frequency increases
- Successful collisions frequency increases
what is the relationship between rate and temperature
Rate increases with temperature:
- Particles have more kinetic energy so move faster
- Collision frequency increases
- Larger fraction of collisions have energy greater than activation energy
- Successful collision frequency increases
what is the relationship between rate and a catalyst
Rate increases with catalyst
- Provides an alternate route with lower activation energy
- Larger fraction of collisions have energy greater than activation energy
- Successful collision frequency increases
how to calculate rate from a graph
gradient
rise/run
what is the instantaneous rate
use a tangent and calculate gradient
what is the initial rate
tangent at t=0
what is the average rate
total rise/total run
what is a maxwell-Boltzmann distribution
the distribution of energies in a collection of particles
what does the area under the curve in a maxwell-Boltzmann distribution represent
the total number of particles
what happens to the curve on a maxwell-Boltzmann distribution when the temperature increases
curve is further right
lower
what does a maxwell-Boltzmann distribution look like on a graph
what happens to the area under at E>Ea when temperature increases on a
area increases
what does a catalyst do to the maxwell-Boltzmann distribution area under the curve after new Ea
area increases
what are the two types of catalysts
homogeneous
heterogeneous
give an example of 2 substances in the same state but different phases
oil and water
dont mix but both in liquid form
what is the difference between homogenous and heterogeneous catalysts
homogeneous is the same phase as reactants and products
heterogeneous is different phase to reactants and products
how do homogeneous catalysts work
it slips the reaction into 2 steps
catalyst’s oxidation number changes in first rection
original catalyst reforms at end of reaction 2
