handouts 1-3 Flashcards
define chemical kinetics
deals with time-dependant chemical processes
how a system evolves far from equilibrium into equilibrium
rule of thumb for temperature
is temp raised 5 degrees reaction rates double around room temp
what does N stand for
number of molcules
units for number of molcules
no units
what does n stand for
number of mols
what is unit for number of mols
mol
what does c stand for
concentration
number of molecules per volume
units for number of molecules per volume
m^-3
dm^-3
cm^-3
what does C stand for
number of mols per volume
what is unit for C
moldm^-3
when is C and c define
in homogeneous reactions
what does collision probability rely on
number density of the molecules
are products or reactants negative stoicheometry
reactants
why is change in mols not useful
different for every component
how to find the amount of products and reactants
divide the change in mols at two different times by the stoichiometric coefficient
what does xi stand for
extent of reaction
what is the extent of the reaction equation
dxi = dni / vi
what is rate of conversion equation
vxi = 1 / vi * dni / dt
why not use rate of conversion for homogeneous reactions
because c or C are used and they are proportional to the number density of molecules
what is differential rate law equation
k capital pi ci ^ mi k is reaction rate constant capital pi product operator (times all of them) ci is all the different coefficients mi is reaction order of each substance
what does differential rate law equation find
reaction rate
units of reaction rate constant
(dm^3 mol^-1)^(m-1) s^-1
what is m
total reaction order
define elementary reaction step
molecules on left come together to form right in side in one step
smallest unit of reaction mechanism
what is molecularity
number of molecules on left in elementary reaction
for unimolecular elementary reactions what are differential rate law equations look like A* = B
vc(t) = - d[A]/dt = d[B]/dt = k[A]
what is units of k in unimolecular elementary reaction
s^-1
how to solve differential rate law unimolecular
separate variables
integrate from c0 / t to c(t) / t
solve integral
what is integrated rate law equation
c(t) = c0 exp(-kt)
how to find conc of B at a time using integrated rate law
[A]0 - [A} = [A]0 - [A]0 exp (-kt)
plotting graph for unimolecular reaction
plot ln(c(t)/c0) = -kt
t is x
y is (c(t)/c0)
the slope is -k
