What determines how matter behaves? Thermodynamics.

Transcription

1 What determines hw matter ehaves? hermdynamics.. What determines hw matter ehaves? Final Stale State Equilirium State Gis free energy: Minimum (at specific, ). Classical thermdynamics Macrscpic phenmena. Statistical thermdynamics Micrscpic descriptin articles : atms, electrns, mlecules. Quantum mechanics raility (distriutin functin) 3. hermdynamics.s. Kinetics Energy hermdynamics: Equilirium state Reactin rate Kinetics: Metastale state 4. hermdynamic systems f materials material system: Unary r/ multi-cmpnent (inary, ternary, quaternary) Hmgeneus/ Hetergeneus Clsed/ Open Nn-reacting/ Reacting Simple/ Cmplex Simple system : energy changes due t mechanical, thermal, and chemical variatin. Cmplex system : energy changes due t gravitatinal, electrical, magnetic and surface effects. Intrductin t the hermdynamics f Materials

2 5. hermdynamic ariales State functins r prcess variales Intensive r extensive variales State functin: a quantity that depends n the cnditin f the system and nt n hw the system arrived at that cnditin. State functin is independent f path. Z Z final Z initial Z Z i f dz e.g.,,, Xk, S, U, G, H, A Fr a very cmplex prcess, Z can e cmputed y the simplest path cnnecting the initial and the final states. State functin can e expressed y exact differential, dz. rcess variale: a quantity that nly has meaning fr a changing system and its value fr a prcess depends explicitly n the path. Wrk, WW, W e.g. Heat, QQ, Q W F d x W. path dz 0, F d x ut W 0 : : r essure d Stress : d. Frce : Electric : dq Magnetic dm Surface tensin : da r Intensive prperty may e defined t have a value at a pint in the system. It des nt depend n the size f the system. e.g.,, Xk, ρ(density),, S, U, H, A, G Extensive prperty depends n the size f the system e.g., S, U, H, A, G, nk Intrductin t the hermdynamics f Materials

3 6. Cncept f state Micrscpic state :statistical distriutin f all cnstituent particles. * Macrscpic state : phenmenlgical prperty f a system. * hermdynamic state f the simple unary system is uniquely fixed when teh values f tw independent variales are fixed. * Any tw prperties culd e chsen as the independent variales., are the mst amenale t cntrl. * Cnsider a pure gas = (,). Equatin f state? If Eq. f state is knwn, we can calculate. (, ) -> (, ), = (-) =? =(,) w paths -> a-> -> -> a a isaric isthermal a a : a ath a : a d d Intrductin t the hermdynamics f Materials

4 Intrductin t the hermdynamics f Materials d d d d d d d ath d d p ) (, d is exact differential. is state functin, path. is indep.f,, Fr any values f,, the gas system is at equilirium nly when it has that unique vlume,, which crrespnds t and. 7. Equatin f state f an ideal gas cnstant, law : cnstant, law : s Charles s Byle v <

5 at ( at ) Byles law : atm is.44 l. Fr ne mle gas : R Fr n mle gas : nr 0 C 73.5K ake : atm,, hermal expansin cefficient ake Cns tan t Charless law : at 0 When lw temperature limit 0K C (K) ( C) 73.5 fr all gas C,,,,, Avgadrs hypthesis : lume per "g - mle"f all"ideal gas"at 0 atm.44 l atm l gas cnstant R mle 73.5K K mle Ideal gas law (equatin f state f ideal gas) : mlar vlume : n N Nte : () atm a 03.5ha m atm liter 0.35 J atm liter J R K mle K mle () Aslute temperature scale (Kelvin) ice pint : 0 C, 3 F atm, H O il pint : 00 C, F 80 Luis & Lussac :hermal expansin cefficient f C is a cnstant. : when 0 hypthetical gas :ideal gas mle vlume f gas is zer, C, "permanent gas" Intrductin t the hermdynamics f Materials

6 Charles s law: =0.5 atm = atm = atm =5 atm K 0 73K Intrductin t the hermdynamics f Materials