Lec' 18 Gases as function of T: Charles Law

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Fred J. Grieman
Lec. 18 Gases as function of T Charles Law
Ideal Gas Law Gas
Density Calculations using Gas Law
HW 5 23, 28, 30, 31, 35,
38, 44
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Gases so far at constant n, T,
______________ (for any gas!) So then P1V1
P2V2 PV f(T) , as T ? , PV ?
e.g., PV ______________________________________
___ PV 30.6 Latm at T 100 ºC, n
1 mol
(P 1atm)
_______
_______
______________
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Scale?? Used Hg in barometer, maybe use somehow
for T Liquid expands with T ? Measure
expansion assume linear
____________

• t (ºC) c0 (distance) c1
• Why is this bad?
• depends on 1 substance
• (temperature is more fundamental than this)
• limited range for Hg
• linear expansion is an approximation

_____________________
_____________________
_____________________________
________
Vary
Measure
______
P (const.) ?
_____________________
At t 0, V Vo rewrite equation ______________
_
Furthermore a same for all gases
_____________________
Which gas?
__________________
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• Results from analysis
• New Thermometer _____________ of substance
  _____________________
• V Vo a t(oC) Vo solve for t
• ___________________________________________
• Measure V at t 0 oC to get Vo V at t
  to be measured
• Hg thermometers are calibrated this way!
• 2) Fundamental Measurement of T (Absolute Scale)
• ______________________________ (as a limit)
  at lowest temperature possible
• _____________________________
• __________________

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3) T (K) 273.15 (V / Vo) so Vgas
(Vo / 273.15) T so
Avagadro Boyle Charles
_____________________
_______________
_________________
______________________________________
____________________________________________
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______________________________________
Gas at 373 K
_________________________________________
density
______________________________________
g mL-1

compare to density of water
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