lecture 4 Flashcards
what is collision theory about
how often particles collide
helps us understand how likely they are to react
what in the arrhenius equation is linked to the collision frequency
pre exponential factor A
collision frequency
Z = N O Vrel
n = number density (N/V)
O = collision cross section
Vrel = mean relative speed between particles
what does the collision cross section depend on
the diameter of both particles
what is the collision cross section equation
ara of a circle: Anr2
r = r1 + r2
mean relative speed equation
similar to mean particle speed
root 8KbT/nu
n is pi
u is reduced mass
difference = reduced mass is used instead of actual mass
collision frequency equations are
given in the booklet <3
if volume is constant, what collision frequency do we use
the one with N
bc N =N/V
z is proportional to rootTEMP
z is collision frequency
(temp is nominator)
if pressure is constant, what collision frequency equation do we use
the o p one
shows how z is inversely proportional to rootTEMP when pressure is constant (temp is denominator)
particle density n issss
total number of particles //// total volume of gas
for the collision frequenzy Z calculations what units does everything need to be in
o: collision cross section - m2 , add both radi in m then square and times by pi.
m: add the 2 masses together then divide by 1000 then avogadros number
pressure should be in pa = 1atm = 101325 pa
what acc is the collision frequency tho
the number of collisions each molecule undergoes per second
what is collision density
collision frequency (z) x number density of particles
what is collision density proportional to
square of number density
square of pressure
definition of collision density
number of collisions occurring per second in a cubic meter of gas
what is the mean free path
distance particles travel between collisions
/\ = Vmean / Z
for a constant volume, mean free path is not dependent on
temperature
temp is not seen in the 1/xxx equation
when the equation has the curly N looking thing this is
N/V
the equation u use when volume is constant
what happens between 2 vessels connecting different gases
diffusion
gases become throughly mixed
what affects the rate of diffusion
concentration gradient
do smaller and lighter particles diffuse faster than heavier and larger ones
yes
what does particles colliding with walls depend on
mean particle speed
number density
what does Zw give us
collision frequency per unit area of the wall
what does rate of effusion depend on
rate of collisions with the walls
when does effusion occur
when the gas escapes through a hole in the vessel
vacuum on the other side
rate of effusion equation
ROE = 1/ ROOT mass
mass in kgmol-1
