4f Flashcards
(40 cards)
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