lecture 3

Question 1

particles have different speeds meaning there is a

Answer 1

distribution
this distribution has a shape

Question 2

how can we measure the speed of a gas

Answer 2

row of spinning discs with slots

the discs spin at different rates leading to particles of different speeds passing by

measuring the number of particles gives the distribution of speeds

Question 3

what is the root mean squared speed based on

Answer 3

finding average speed using the pressure the particle it exerts

Question 4

root mean speed squared and pressure

Answer 4

pV = 1/3n NA m Vrms2

pV = 1/3n M Vrms2

m=mass
M=molar mass

Question 5

root mean speed squared equation

Answer 5

root 3KBT/m

root 3RT/M

Question 6

what does root mean square speed allow us to do

Answer 6

determine the average kinetic energy of particles

Question 7

what is the average kinetic energy of a particle

Answer 7

1/2 m vrms2

Question 8

what is the total kinetic energy of an ideal gas

Answer 8

3/2 nRT

Question 9

maxwell distribution graph is

Answer 9

unsymmetrical

Question 10

3 types of average speed

Answer 10

most probable
mean speed
root mean squared

Question 11

most probable speed

Answer 11

peak of maxwell distribution

diff of y axis = 0

root 2KBT/m

temp in k
mass: /1000 /avo

ms-1 units

Question 12

mean speed aka Vmean

Answer 12

higher than most probable

root 8KbT/nm

n is pi
m: /1000 /avo
temp in k

ms-1 units

Question 13

root mean square speed

Answer 13

higher than most probable and mean speed

root 3KbT/m
root 3RT/M ???

temp in k
m: /1000 /avo

ms-1

Question 14

what are the 3 speeds and what are they all proportional to

Answer 14

most probable
mean
root mean squared

probable to root(KbT/m)

Question 15

what do the 3 speeds tell us about the distribution of speeds

Answer 15

based on mass and temp
not on pressure or volume.

same temp = same speed
no matter the vessel theyre in

ratio of T:m determines the speeds of particles: all the speeds have T nominator and m as a denominator

Question 16

what does changing the temp do to the distribution of speeds

Answer 16

changes them
lower temp = lower most probable speed

changes width and hight but not shape

Question 17

what changes distribution of speeds

Answer 17

temp: higher temp = wider = larger mist probable speed, change in height and width

mass: lower mass = wider distribution.

low mass == hotter temp shape

Question 18

distributioon of kinetic energy doesnt depend on what

Answer 18

doesnt depend on the mass

depends on temp only

explains why the ideal gas equation can be applied to all gas - based on temp and not mass aka its identity

Question 19

on average particles in an ideal gas collide

Answer 19

elastically

total amount of kinetic energy remains the same // unchanged

Question 20

distribution of kinetic energy graph

Answer 20

more asymmetric than speed maxwell boltzmann graph.

basically a 1s wavefunction - up down

Question 21

most probable kinetic energy equation

Answer 21

peak of kinetic energy distribution graph

Emp = KbT/2

Question 22

mean kinetic energy on distribution of kinetic energy graphs

Answer 22

higher than most probable

3KbT/2

same as the Vrms

Question 23

what affects the distribution of kinetic energys on a distribution graph

Answer 23

look at the equations - the TEMPERATURE

changes the height and width not shape

effect of temp is more pronounced than speed - dependence is linear - there is no square root in the equation but there was for the speed distributions.

Question 24

why is the effect of temp on kinetic energy distributions more pronounced

Answer 24

dependence is linear

there is no square root in the kinetic energy equations

Question 25

what does the kinetic energy distributions tell us

Answer 25

how much energy is involved when 2 particles collide

helps us know if they will react or not

how many collisions have above the Ea - proportional to exp(-Ea/RT) - matches the rate constant ‘k’

Question 26

what describes the distribution of speeds

Answer 26

maxwell boltzman distribution

Question 27

what affects the maxwell distribution and how

Answer 27

mass and temp

smaller mass + larger temp = shorter and wider = increase in average speeds

Question 28

what describes the kinetic energy of a particle

Answer 28

distribution graph

Question 29

what affects the kinetic energy distribution graph and how

Answer 29

increasing the temp widens the graph

larger average kinetic energy

Question 30

particles with more than the Ea is proportional to

Answer 30

exp(-Ea/RT)

explains temp dependence of rate constant.