# CHM135H1 Lecture Notes - Lecture 9: Kinetic Theory Of Gases, Molar Mass, Btg Pactual

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26 Sep 2018
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CHM135 LECTURE 9: Liquids, Solids and Phase Changes
September 24, 2018 (Relevant Reading Chemistry 7ed McMurray/Fay/Robinson Chapter 11.1-11.4 and
11.6-11.9)
Review The Molecular View: Kinetic Molecular Theory
- gas made of tiny particles (atoms or molecules) moving randomly
- Volume of particle very small compared to size of container. (most of gas empty space)
- Particles arent attracted or repelled by each other
- Particle collisions are elastic (no energy lost through friction)
o No energy is lost during collisions, so total kinetic energy in container remains constant
- Kinetic energy increases with temperature in Kelvin. KE = 

- Within a gas sample, different particles of gas have different amounts of kinetic energy
- Within a sample of gas, theres a distribution of speed
- KE = 


  

; M = molar mass
1)Which speed distribution belongs to the gas with
the highest molecular mass? Assuming temperature
is the same A, because increased molar mass results
in decreased speed
2) Which speed distribution belongs to the gas with
the highest temperature? Assuming gas is the same
C, because increased temperature results in an
increase in speed
(diagram taken from Lecture 7 powerpoint, slide 11)
3) A 1.98L vessel contains 215 g (4.89 mol) of CO2 at 299K. Calculate the ideal gas pressure and the
van der Waals gas pressure, where a is 3.59
 and b is 0.0427
 . Compare to the actual
pressure of 44.8 atm
Pideal PV = nRT, P = 



Pvan der Waals   




 


Pactual = 44.8 atm; the closest value was given by the van der Waals equation
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