L22S07_RealGases, PhasTransitions 03-09-07

L22S07_RealGases, PhasTransitions 03-09-07 - CHEM 1A...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: CHEM 1A L22: "Real Gas Behavior, Phase Diagrams" Kinetic Theory of Gases P(V, No, m, v) ~ Distribution of Speeds vrms Previously ~mv ~ N0v V Average over v2 --=mean square speed v2 Momentum Transfer * Number of collisions per unit t,A (frequency) F(v) vrms Maxwell-Boltzmann MaxwellHigh T Low T Low m High m P= -- N0mv2 3V A.Pines,M.Kubinec,UCB L15-7 v A.Pines,M.Kubinec,UCB L15-8 Pressure,Energy and Temperature PV= 3 N 0mv2 -- Ek T Root-Mean-Square Speed Root- Meanvrms= -- v2 = 3kBT = m 3RT 3RT M -- N (mv2) = RT = 3 0 2 Ek Ek = 3 2 ek RT ek = 3 2 k BT R=8.31 J/K mol kB=1.381 x 10-23 J/K L20-6 A.Pines,M.Kubinec,UCB Per mole Per molecule vrms~ T M L22-1 L15-11 UC Regents 2004 M. Kubinec kB=R/N0 ChemQuiz 21.3 What is the vrms (m/s) for Br2 at 300 K? K? 1) ~ 1 2004 M. Kubinec 2) ~ 10 3) ~ 100 L22-2 Distribution of Speeds vrms F(v) vrms Maxwell-Boltzmann MaxwellHigh T Low T F(v) proportional v2 e F(v) Low m High m -E/kBT E/k v (ms-1) 2004 M. Kubinec L22-4 2004 M. Kubinec 1 CHEM 1A L22: "Real Gas Behavior, Phase Diagrams" ChemQuiz 21.4 Shown is the MB F(v) distribution at ~300 K for Br2 and X. What is X? Br2 vrms X vrms v Molar Mass Ne Ar Br Kr 20 40 80 83 1) Ne 2004 M. Kubinec 2) Ar 3) Kr L22-5 Real Gas Behavior P Summary V P Tc V V =- 1 V V P Ideal: PV=const A.Pines,M.Kubinec,UCB Real: PV = ? L16-21 2004 M. Kubinec L22-7 Ideal Gas Behavior P =- 1 V V P Ideal Gas: Decreasing Compressibility Ideal: PV=const 2004 M. Kubinec V P1 < P2 < P3 < P 4 L22-8 2004 M. Kubinec 2 CHEM 1A L22: "Real Gas Behavior, Phase Diagrams" Real Gas Behavior P Real Gas: Phase Transition Tc V P1 Real: PV = ? 2004 M. Kubinec < P2 = P3 < P4 L22-9 ChemQuiz 22.1 P Which is true of the Tc for any real gas ? Tc V 1) < ideal gas 2) = ideal gas 3) > ideal gas 2004 M. Kubinec L22-10 Van der Waals Equation n2 P+a 2 V a: adjust `P' for collisions/attractions V - nb =nRT b: adjust `V' for finite volume of molecules He CO2 H2O 2004 M. Kubinec a 0.034 3.59 5.46 b B.P. (K) 0.024 4.2 0.043 0.030 195 373 L22-12 2004 M. Kubinec 3 CHEM 1A L22: "Real Gas Behavior, Phase Diagrams" Real Gases: Vapor Pressure P(atm) P(atm) Vapor Pressure Water 1.000 0.031 Tc 100 oC 25 oC V L22-13 2004 M. Kubinec CO2 S P Phase Diagram L Triple Point TTP = -56.6 oC PTP = 5.1 atm G Temperature Tc L22-14 2004 M. Kubinec ChemQuiz 22.2 Which plot corresponds to the process shown ? P S L G P P P T Tc 1) 2) V V 3) V L22-15 2004 M. Kubinec 2004 M. Kubinec 4 CHEM 1A L22: "Real Gas Behavior, Phase Diagrams" H2O S P G Temperature 2004 M. Kubinec Phase Diagram L Triple Point TTP = 0.01 oC PTP = 4.6 torr Tc L22-17 ChemQuiz 22.3 Which is a plot of the vapor pressure of water vs. T ? P P P S L G P T Tc 1) T 2004 M. Kubinec 2) T 3) TL22-18 ChemQuiz 22.4 Which is the 373 K isotherm for water ? P S A B C L G T Tc 1) A 2004 M. Kubinec 2) B 3) C L22-20 2004 M. Kubinec 5 CHEM 1A L22: "Real Gas Behavior, Phase Diagrams" Lecture Complete 2004 M. Kubinec L22-22 2004 M. Kubinec 6 ...
View Full Document

This note was uploaded on 08/19/2009 for the course CHEM 1A taught by Professor Nitsche during the Spring '08 term at Berkeley.

Ask a homework question - tutors are online