Topic 2b- kinetics (reaction mechanisms) Flashcards
Does reaction rate increase with temp
yes
activation energy
minimum amount of energy required for reaction
-also known as the transition state on the graph
what happens at activated complex/ transition state
reactants rotate into products
bigger activation/ larger kj will be faster or slower?
slower
arrhenius equation
ln k= -ea/RT + Ln A
-RT is 8.314 because kj
how to find ea (activation energy)
-slope x R
what are our indicators for arrhenius
temp and rate
what is the actual process called going from reactants to products
reaction mechanism
-includes elementary reaction or elementary process
molecularity
how many molecules are involved in the process (how many products: rate law exp, ratio count/amount of reactants)
-eg. unimolecular, bimolecular, thermomolecular
when crossing out reactions between each step what do we need to make sure off
they are on opposite sides of the arrows and it determines intermediate
Ea1 will always be _________ than E2
greater
because thermomolecular are rare, this rate law suggests
two step reaction mechanism
what determines the rate
slow step
forward and reverse reactions (equilibrium) will have what step first
fast first
relationship between forward and reverse
they are equal to each other
SN1 and SN2 step
1: two step
2: one step
catalysts increase what
the rate of reaction by decreasing activation energy
catalyst productions
-efficient (drive reaction)
-cheap (abundant)
-abundant (available)
-robust (needs to work)
enzymes
-bio catalyst
-lock and key method
-position in active site can help break down more
rate limiting step isnt usually known, what do we use
steady state approx
reaction rate steps
-cross out and find intermediates
-write consuming rate laws (should be 3: 1st prod, 2nd prod, and both intermediates in one)
-formula of IM = to one not solving for
-isolate the [ ] and divide to other side
-use the formula above and insert for the [ ] your solving for, the other [ ] rate law needs from 2nd prod needs to be put on top as well as k2 goes back in
whats the formula for two point arrhenius
Ln k2/k1= -ea/R (1/t2 - 1/t1)
our over all rate law will be found in
slow step
if slow step isnt know, what do we need to do
steady state aprox
rate laws will have to do with
reactant side only (consuming)
k-1 backwards
when a reaction says it triples or doubles what do we do? for triples what does it go over
-ln 2, ln 3
k3/k1
we will usually solve and take out _______ for finding fast and slow
k-1, intermediate taken off after being brought out
-intermediates will NOT be in rate law
for two steps with k3, how to we determine rate law
-if slow in first, we can determine right away
-if slow is in 2nd or 3rd and we have intermediate, we need to use steady state approx
-if we don’t know, we need to use steady state approx
