4f Flashcards
how do we solve rate equations numerically
we get given a reaction mechanism // operations
and we need to set up differential mechanisms to describe the change in conc for each of the elements in that mechanism
we look at every element in all the mechanisms
and we write a differential equation for each one where we include what forms and what destroys it!!
like we normally do
and then we can solve these using diff methods to tell us the slope of the change of conc at a particular time / point
knowing where the slope is helps us predict where the next point is going to be
when u write differential equations,, when do u need to put 2K1 or a larger number in front of the k
u add a 2 in front of the k when u form 2 of that thing following the arrow.
aka if we’re writing an equation for NO and the formation of it is 2NO and ur going from N2O2 to 2NO
the k ,, aka rate constant will be 2k bc ur making 2 of them
aka the rate is 2 times faster
so we add a 2 to say this
eulers method is what
when u use the equations to tell u the slope of the change of conc at a particular point
and knowing where the slops is will help us predict where the next point is going to be.
describe the graph for eulers method
u have conc of the reactant on the y axis
u have time on the x axis
u then have a curve
u obvs know the [NO]o and the [N2O2]o so u just guess what the k values are
and this will give u a slope and the gap between t zero and t of the end of the slop is called h
and then u predict what the [NO] is at the point h
then u use this to predict rate of [N2O2] to predict [N2O2].
then u just keep predicting the slope at diff times
and obvs the slopes we make are not exactly the slop we have
but we keep altering the values until we match that slope
whats the runge kutta 4th order
its easily programmed for small sets of equations
it helps us solve the differential equations
by taking lots of small recordings,, make sure the h is super small bc the smaller h is,, the more accurate ur predictions are.
whats is the principle of reversability
at equilibrium, each individual step in a mechanism is also at equilibrium
so the forward reaction follows the same path as the backward one
u go from A to B to P and the back reaction is the same as the forward one,, meaning if the forward one is hard to measure,, we can measure the backward one.
this is what u do for menthol synthesis
whats an enzyme
a biological molecule that acts like a catalyst
it lowers the activation energy barrier
its very specific meaning it only catalyses specific reactions
michaelis menton mechanism : enzyme reaction ,, describe it
E + S <—> ES —> E + Z
E = enzyme
S = substrate
ES = enzyme substrate complex
E = enzyme
Z = product
whats [E]o
initial enzyme conc
what do we apply to [E]o
we apply the steady state approx
to find the rate, v,
whats the rate, v, equation for the michaelis reaction
v =
k2 [E]o [s] // (k-1 + k2 / k1) + [s]
= V[S] / km + [S]
where km is the michaelis constant
whats V in the Michaelis simplified equation
V = k2[E]o
when we have the michaelis equation type thing,,, what do we plot on a graph
Rate,, v on y axis
[S] on the x axis
and u get an ‘r’ type curve
when we plot rate against [s] on the michaelis graph,, what is the top of the ‘r’ curve thing
that is the limiting rateeeee
aka the conc of substrate is so high that all the enzymes are used up meaning if u add any more substrate,, it doesnt change the rate at all,, bc all enzymes are used up duhhh.
in the michaelis plot of rate on the y axis and [s] on the x axis,, what is the half the rate
v/2
rate in the michaelic equation is whattt, and what does it mean when we have a large [s]
the rate equation is
V[s] / Km+[S]
is u have a larger [s] it means that Km is kinda irrelavent
meaning rate = V[s] / [s] and then u cancel out the [s] so rate = V
V in terms of {e]o
V = [E]o K2
when [s] = km,, what does this do to the v,, rate equation
rate = V[S] / 2[S]
and then we cancel the [s] out and we get
rate = V/2
so finding v/2 gives us the s value on the x axis where it equals to km
to look at enzyme data what do we do
we look at the lineweaver burt plot
axis on a lineweaver burt plot
mol-1 s aka 1/v on the y axis
1/[s] aka mol-1dm3 on the x axis
in the lineweaver plot what is the slope of the line
slope of the line = km/m
aka the limiting rate
name 3 types of chain reactions
polymerisation
combustion
explosions
what does a chain recation involve
a chain reaction involves an intermediate that is regenerated so that a small amount produces a lot of product
name the 3 types of eleentary steps a chain reaction usually has
initiation
progagation
termination
whats initiation step in a chain reaction
gemerates the chain carrier
whats propagaetion i na chain reaction
produces products and regeerates the chain carrier
whats the termination step in a chain reaction
it destroys the chain carrier
what 2 steps can a chain reaction have but isnt certain to have
inhibition step
branching step
describe what the inhibition step is in chain reaction
destroys product and slows the reatcion
whats the braching step in a chain reaction
it creates more chain carriers than it destroys
it can lead to explosions
how can u tell a reaction equation is a initiation step
if ur going from 2 molecules to an excited state oneee
the excited state is the chain carrier
whats the initiatiopn step usually involving
it normally involves an inert body
aka the wall of the chamber etccc
we call this M
when an excited state reaction with smt random to give another excited state what step do we call this
we call it the propagation step
as it produces products (stabilises the excited state) and regenrates a chain carrier (makes the other part of what u used to neutralise the chain carrier to a diff chain carrier.)
aka Br* + H2 —> HBr + H*
what step is it when we have H* + Br2 —> HBr +Br*
we call this the propagation step
when u have H* + HBr —> H2 + Br* what do we call this
we call this the inhibition step
bc ur destroying the HBr product ,, slowing the reaction.
what is the termination stepp,,, aka what will the equation look like
u will have 2 excited states aka 2 chain carriers and theyre gonna turn into a neutral molecule.
aka the chain carrier is gonna be destroyed.
what is polymerisation an example of
its an example of a chain reaction
what different types of polymerisation are there
theres step and chain polymerisation
whats the diff between step and chain polymerisation: first explain step polymerisation
- chain growth forms between any 2 molecular species
A-B + A-B –> A-BA-B
A-BA-B + A-B –> A-BA-BA-B
any 2 monomers or dimers or oligomers can react,, not just the chain ends
whats the diff between step and chain polymerisation: aka whats chain polymerisation
it only occurs between a monomer and a growing chain. monomers are only added to the active chain end.
A-BA-B + A-B –> A-BA-BA-B
aka growth happens one monomer at a time.
so u have a train and it keeps picking up carridges as it stops at stations
