9. kinetics I (as) Flashcards
particles must …. to react
collide
collision theory
- collide in the right direction ( need to be facing each other the right way)
- they collide with at least a certain minimum amount of kinetic energy
activation energy def
the minimum amount of kinetic energy particles need to react
Maxwell-boltzmann distribution
plot a graph of number of molecules in a substance with different kinetic energies
things that affect reaction rate
- concentration
- pressure
- temperature
catalysts
increasing conc causes
sped up reactions
more particles in a volume particles collide more frequently ,, more chance to react
increasing pressure (gas) causes
reaction to be sped up
more particles in a given volume ,, increase frequency of successful collisions
catalysts cause
sped up reactions
lower activation energy by providing an alternate pathway for bonds to be broken and remade
more particles have enough energy to react
reaction rate def
how fast reactants are converted to products
rate of reaction calculation
amount of reactants used or products formed/ time taken
catalysts
increase rate of reaction by providing an alternate pathway with a lower activation energy so greater proportion of collisions result in a reaction
catalyst chemically unchanged at the end of reaction
heterogenous catalysis
is a catalyst that is in a different phase form the reactants
heterogenous catalysis explained
reaction happens on the surface of the heterogenous catalyst
increasing surface area of catalyst increases the number of molecules that can react at the same time. ,, increase rate of reaction
how does heterogeneous catalyst work
lower activation energy of the reaction
solid heterogenous catalysts can
provide a surface for the reaction to take place on
how does solid heterogeneous catalyst work
-reactant molecules arrive at the surface and bond with the solid catalyst (adsorptions)
-bonds between reactants atoms weakened and break up and form radicals and radicals get together and make new molecules
-new molecules are then detached from the catalyst (desorption)
adsorption def
reactant molecules arrive at the surface and bond with the solid catalyst
desorption def
new molecules are then detached from the catalyst
homogenous catalysis are
catalysts in the same physical state as the reactants
during homogenous catalysis
reactants combine with catalyst and make an intermediate species which then reacts to form the products and reform the catalyst.
catalysts have economic benefits
lower production costs and give more product in a short time and help make better products
