Lecture 9

Lecture 9 - CHAPTER 5: Gases ) Reading assignment: 5.1 to...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
CHAPTER 5: Gases ) Reading assignment: 5.1 to 5.11 inclusive Homework: 21, 23, 27, 31, 37, 41, 53, 57, 61, 71, 83, 93 Three distinct physical phases of matter: olid Solid Liquid Gas 1 Atmospheric Chemistry Experiments Used to Refine Theory
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Gases: Basic Properties ressure = Force/Area Gas exerts Pressure Gas Pressure = Force/Area A F P / = imensional analysis dimensional analysis ma F = 2 l A = 2 m N ] P [ = 1 N/m 2 = 1kg/m . s 2 = 1 Pa SI Unit of Pressure very small 2 Often use: 1 atm = 101,325 Pa = 760 mmHg = 760 Torr 1 atm is special because it is ~ pressure exerted by air in the atmosphere
Background image of page 2
Torricelli’s Experiment Torricelli’s Barometer 1600s Air exerts pressure akes Hg stop falling at a level ~760mm above Hg in dish Makes Hg stop falling at a level ~760mm above Hg in dish At equilibrium, P in = P out (F/A) in = (F/A) out (mass Hg) * g (V * * g F = (mass Hg) g F = (V ρ Hg ) g F = (h * A * ρ Hg ) * g P = (h * ρ Hg ) * g P = (76cm * 13.6g/cm 3 ) * 980cm/s 2 50km P = 1*10 5 kg/m . s 2 Recall, 1 atm = 101,325 N/m 2 = 101,325 kg/m . s 2 atmosphere, 1 Hg 3 to top of 760 mm
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Manometer We can use the same principle to measure P of any gas, 4 If gas has pressure of 1atm (P atm ), heights are identical. P gas = P atm –h±=±P atm + h Æ h = 0
Background image of page 4
Three Important Gas Laws Æ Ideal Gas Law eal Gas Law: PV = nRT Ideal Gas Law: PV = nRT ressure * volume = oles * gas constant * temperature pressure volume moles gas constant temperature Boyle’s Law: PV = constant [at constant T and n] Charles’ Law: V/T = constant [at constant P and n] Avogadro’s Law: V/n = constant [at constant T and P] 5
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Boyle’s Law Boyle’s Experiment ~ 1660: ecall the manometer: h = 0 for P = 1atm Recall the manometer: h = 0 for P = 1atm Add some Hg; h > 0; Note Volume of Air Add some more Hg; P is higher; h >> 0 olume of gas has decreased! Volume of gas has decreased! P V 6
Background image of page 6
Boyle’s Law piston: position to set gas volume gauge: measure gas pressure Perhaps more easily understood with more modern apparatus P V Allow heat to flow across cylinder wall to keep temperature constant 7 http://college.cengage.com/chemistry/discipline/shared/protected/fae/general/index.html?layer=act&src=qtiwf_act037.1.xml
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Boyle’s Law V P We said: But, how in particular does pressure change with volume in an ideal gas?
Background image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/03/2011 for the course MATH 1090 taught by Professor Greenwood during the Spring '08 term at MIT.

Page1 / 22

Lecture 9 - CHAPTER 5: Gases ) Reading assignment: 5.1 to...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online