《无机化学简明教程》课件-Chapter 14 Elements in d Block

1Chapter1StateofSubstances1

Gas1-1TheIdealGasEquationofState1-2Dalton’sLawofPartialPressures1-3TheKinetic-MolecularTheory

1-4RealGases2Liquid2-1EvaporationofLiquids2-2VaporPressure,C-Cequation2-3BoilingPointofLiquid3Solid24Plasma(等离子体)等离子体即指其中离子所带的正、负电量是相等的[地球上只能在实验条件下产生]氘气，D2→D2++e－自然界中大量存在，宇宙中绝大多数（大于99%）的物质是以等离子状态存在的，地球电离层、极光、闪电。35Superhidensity(超高密度态)Atveryhighpressures(greaterthan200atm),somegaseousmixturesconsistofmorethanonephase.Eg.heliumandxenon在高压下物质的结构会产生很大的变化例1：绝缘→导体，半导→导→超导例2：104Pa下，95℃的会凝固成冰（热冰）例3：106Pa时，H2(l.)可导电，并具有稳定的电导率41

Gas1-1TheIdealGasEquationofState(1)IdealGasItisanidealmodel:Agaswhichhasquantitybutnovolume,withoutinteractions,withoutlosingkineticenergywhencollideswitheachother.具有质量的几何点，只有位置而不占有体积，分子间无相互引力，发生碰撞没有动能损失.Underhightemperatureandlowpressure(T>0℃；P~severalatmospherepressures，P→0)Thedistanceamongmoleculesaremuchbiggerthanthemoleculesize,whichmeansthatcomparedwiththegasvolume,themoleculevolumeisverytiny.Interactionsamongmoleculescanbeneglected.5(2)TheIdealGasEquationofStateBoyle'slawV=constantB/P(T,nconstant)Charles'slawV=constantC

×T(P,nconstant)Avogadro'slawV=constantA

×n(T,Pconstant)

V=aconstant(Tn/P)

PV=nRT

6PV=nRT

P---PaV---m3n---molT---K(Kelvin)R--gasconstantR=PV/nT

=(1atm)(22.4141L/(1mol)(273.15K)=0.082atm·L/mol·K

=8.314J/mol•K7CalculateρandM：PV=nRT=mRT/Mρ=m/V=PVM/RTV=PM/RT

M=ρRT/P8Example:It’sfoundthat0.896gofapuregaseouscompoundcontainingonlyNandOoccupies0.524Latapressureof0.973×105Paandatemperatureof28.0℃.Whatarethemolecularweightandmolecularformulaofthegas?Solution：n=m/M=PV/RT∴M=mRT/PV=0.896×8.314×301/(0.973×105×0.524×10-3)=43.98g/mol∴ThemoleculeisN2O.91-2Dalton’sLawofPartialPressurespartialpressure:thepressureofeachgasinamixture.Ptotal=P1+P2+…=∑Pi

∵P1V=n1RTP2V=n2RT…PiV=niRTPtotalV=(P1+P2+…+Pi)V=(n1+n2+…+ni)RT=ntotalRT∴Pi/Ptotal=ni/ntotal=XiPi=Ptotal·Xi

Xi:molarfraction（摩尔分数）10Example:Whenamixtureofpotassiumchlorateandmanganesedioxidewasheatedtodecompose,itsquantitydecreased0.480gandanoxygenof0.377dm3wasobtainedbydrainingwatermethod(排水集气法)。Thetemperatureis294Kandpressureis9.96×104Pa.Pleasecalculatethemolecularweightofoxygen.(Andthesaturatedvaporpressureis2.48×103Pa.)Solutions：

MnO2,△2KClO3(s.)→2KCl(s.)+3O2↑MO2=mO2/nO2

Ptotal=PH2O+PO2

∴PO2=Ptotal－PH2O=9.96×104－2.48×103=9.71×104(Pa)nO2=PO2·Vtotal/RT=9.71×104×0.377×10－3/(8.314×294)=0.0150(mol)MO2=mO2/nO2=0.480/0.0150=32.0(g/mol)

11Example:AsampleofPCl5(g.)weighing2.69gwasplacedina1.0Lflaskandcompletelyvaporizedattemperatureof250℃.Thetotalpressureobservedatthistemperaturewas1.00atm.ThepossibilityexiststhatsomeofthePCl5mayhavedissociatedaccordingtotheequationPCl5(g.)=PCl3(g.)+Cl2(g.)WhatmustbethefinalpartialpressuresofPCl5,PCl3andCl2undersuchexperimentalconditions?Solutions：nPCl5=2.69/MPCl5=2.69/208=0.0129(mol)P=nRT/V=0.0129×8.314×523/10－3=5.609×104(Pa)SinceP<1.00atm，somedissociationofPCl5musthaveoccurred.

12

PCl5(g.)=PCl3(g.)

+Cl2(g.)

t=00.012900te0.0129－nnnPV=ntotalRT∴ntotal=PV/RT=1.013×105×1×10-3/(8.314×523)=0.0233=0.0129+n∴n=nPCl3=nCl2=0.0104molPPCl3=Ptotal×nPCl3/ntotal=1.013×105×0.0104/0.0233=0.4520×105(Pa)PCl2=PPCl3PPCl5=1.013×105×(0.0129－0.0104)/0.0233=0.1087×105(Pa)13Whenthetemperatureandpressureisconstant,thetotalvolumeofamixtureofgasesisequaltothesumofthepartialvolumesofthegasesinthemixture.Vtotal=V1+V2+…Xi=Vi/VtotalProof：

PV1=n1RTPV2=n2RTPVi=niRTP(V1+V2+…+Vi)=(n1+n2+…+ni)RTPVtotal=ntotalRT∴Vi/Vtotal=ni/ntotal=Xi14Severalquestionsconcerninggasmoleculesmovement:Howtomove?TherelationsamonguandP、V、n、TThedistributionofuIfu>100m/s,whywecannotsmelltheodorofH2Sinstantly?151-3TheKinetic-MolecularTheory

----AModelforGasBehavior(1)SupposeGasiscomposedofmolecules.Moleculesareinconstantmotion,inarandomway.0~lightspeed3×108m/sAlldirectionsSpeedchangesrapidlyMoleculesdon’taffecteachotherexceptelasticcollision.16（2）TheKinetic-MolecularTheorySupposingthatthereareNgasmoleculeswhoseweightisminacubelmonanedge，1/3moveupanddown,1/3movebackandforth,and1/3moverightandleft.今考虑一个分子，速度为u1左右运动,该分子每撞壁一次动量改变的绝对值为2mu1,△t=2l/u1

单位时间内动量的变化就是力

F=2mu1/△t=mu12/l17N1+N2+N3+…=N/3速度平方的均数

18rootmeansquarespeed(根均方速率)19玻尔兹曼常数k=R/N0=1.38×10-23J/KMeaningoftemperature：T∝EvEv∝TAtcertaintemperature,theaveragekineticenergyisthesame.20(3)ApplicationsDeducePartialPressureLawandDiffusionLawCalculatethespeedofmolecule21DiffusionLawIn1831GrahamdiscoveredthatifTandPisconstant,

M=ρRT/P

∵EA=EB2223Example:Calculatetheroot-mean-squarespeedofH2Smoleculeat298K.Solution:24Table.Theroot-mean-squarespeedofsomemoleculesat298K

MoleculeSpeed(m/s)H21930He1360H2O642O2482H2S468Ar431CO2411Xe23825(4)speeddistribution——speeddistributionfunction

就大量分子而言，一定条件下、T一定，每个分子的u随时不断地改变，完全是偶然的、随机的。求单个分子的速率不仅没有意义，而且不可能，速率分布遵循统计规律。我们可以求出u→u+△u内分子数△Nu：△Nu∝N·△u△Nu还与u有关.例：10～20m/s,410～420m/s，△u=10m/s；关系复杂，不是简单的正比例关系。用一个由u表示的函数f(u)来表示。

△N=Nf(u)△uf(u)=△N/(N△u)物义：分布在速率u附近单位速率间隔内的分子数占总分子数的比率(百分数).26Themostprobablespeed最可几速率AveragespeedTheroot-mean-squarespeedF(u)2728explanations：①u=0oru→∞，little；whiletherearemanymoleculeswhosespeedsuareinmiddle②Theareaunderthecurveis1③u→u+△u之间的阴影面积表示速率为u→u+△u的分子数占总分子数的分数29Figure1.2Distributionofmolecularspeeds30④Atthesametemperature，thespeeddistributionofdifferentgasesO2,N2,H2O,H231(5)Energydistribution（whichissimilartospeeddistribution)321-4RealGases

(1)compressibilityfactorPV/nRT

333435(2)VanderWalls(范德华方程)

1873年，荷兰Vanderwalls分析引起偏差的两个原因：实际气体分子自身体积，使分子可以活动的空间减小，V－nb分子间作用力，使得分子不能全力以赴的碰撞器壁内层分子对碰撞器壁分子的引力和内部分子的密度成正比，也和碰撞的外层分子的密度成正比P内∝(n/V)2，即P内

=a(n/V)2修正：(P+an2/V2)(V－nb)=nRT

实际气体碰撞气体所产生的压力<理想气体碰撞气体所产生的压力36（3）liquefraction（液化作用）Experimentsshow：①T↓Eg.N2bp.=-196℃②T↓andP↑，criticalconstant(临界常数)Tc：加压下使气体液化的一定TPc：在Tc时所需的最低PVc：在Tc、Pc时1mol气体所占的VLowTcindicatesthegasisdifficulttobeliquefied,whichhassomerelationshipwithmolecularstructure.37Non-polarmolecules,suchasHe、H2、N2、O2，interactionsamongmoleculesareverysmall,thustheyaredifficulttobeliquefied.Eg.N2Tc=126K（-147℃）,Pc=3.39×106Pa≈30atmCO2Tc=304.1K（31℃）,Pc=7.39×106Pa≈70atm38当气态物质处于Tc、Pc和Vc时，气、液T>Tc气相T=Tc两者无别，不够稳定的特殊状态。（液态）T<Tc气、液共存392Liquid2-1EvaporationofLiquids(1)vaporpressure

referstothepressureofliquidvaporformedbyevaporationofliquidinaclosedcontainer.与其本身的液体同在一处的气体，其压力叫蒸气压。40(2)Saturatedvaporpressure

Themaximumpressureofaliquidvaporformedbyevaporationoftheliquidinaclosedcontainerdependsonlyonthetemperatureoftheliquid.当V蒸=V凝时，动态平衡，此时的蒸气叫饱和蒸气，所产生的压强只与液体本身及T有关，与液面上方空间的V、液体的量无关。41Et2O,Acetone,EtOH,H2O42同一液体，T↑，Ni↑（Ek大的），逸出的分子数↑，P↑同一温度下，液体分子间作用力强，分子难以逸出，蒸气压P就小。eg.作用力H2O>C2H5OH>CH3COCH3>(C2H5)2O∴同一温度321K时P：H2O<C2H5OH<CH3CO