《工业分析 Industrial Analysis》课件-韦氏天平法和密度计法测乙醇密度（双语）

项目八：常规物理常数与性能分析任务四：液体密度的测定

韦氏天平法和密度计法测定乙醇密度课程：工业分析中文Scenario8:PhysicalconstantsandperformancetestingTask4:DeterminationofliquiddensityDeterminationofethanoldensityusingWechslerbalancemethodanddensitometermethodCourse:IndustrialAnalysisEglish1、测定原理一、韦氏天平法测定乙醇密度中文1、Measurementprinciple一、DeterminationofethanoldensityusingWechslerbalancemethod

ArchimedeslawAnobjectimmersedinaliquid(orgas)issubjectedtoupwardbuoyancy,whichisequaltotheweightoftheliquiddisplacedbytheobjectThecalculationformulais:Fbuoyancy=ρliquid·g·Vliquid=mliquid·gEglish韦氏天平法测定液体密度时是在一定温度下，分别测定同一物体-浮锤在水及试样中的浮力。当浮锤完全浸没在液体中时，由于浮锤排开水和试样的体积相同，而浮锤排开水和试液的体积为：

V排水=F水/（gρ水）=m水/ρ水V排试液=F水/（gρ试液）=m试液/ρ试液所以中文

TheWechslerbalancemethodisusedtomeasurethebuoyancyofthesameobject-afloatinghammer-inwaterandasampleatacertaintemperature.Whenthefloathammeriscompletelysubmergedintheliquid,asthevolumeofwaterdischargedbythefloathammeristhesameasthatofthesample,thevolumeofwaterdischargedbythefloathammerandthevolumeoftestliquidis:Vwater=Fwater/（gρwater）=mwater/ρwaterVdrainagesolution=Fwater/（gρdrainagesolution）=mdrainagesolution/ρdrainagesolutiontherefore:

Eglish2、仪器：韦氏天平中文2、Instrument:Websterbalance1.Supportbracket;2-regulator;3-pointer;4-Crossbeam;5-Knifeedge;6-Gamecode;7-Smallstructure;8-Finewhitegoldwire;9-Floathammer;10-Glasscylinder;11-AdjustingscrewsEglish3、测定方法（1）安装韦氏天平

（2）用等重砝码调节平衡（3）向玻璃筒中注入煮沸30min并冷却至20℃的水，将浮锤浸入水中，玻璃筒置于20℃的恒温水浴中，将游码挂在横梁相应位置使天平平衡，记录读数。中文3、Measurementmethod(1)

InstallingaWechslerbalance(2)Adjustingbalancewithequalweightweights(3)Injectwaterthathasboiledfor30minutesandcooledto20℃intotheglasscylinder,immersethefloathammerinwater,placetheglasscylinderinaconstanttemperaturewaterbathat20℃,hangthefloatcodeatthecorrespondingpositiononthecrossbeamtobalancethebalance,andrecordthereading.Eglish（4）将玻璃筒中水倾出，玻璃筒及浮锤先用乙醇，再用乙醚洗涤数次，吹干。注入预先调整至20℃的乙醇，同样置于20℃的恒温水浴中。调节游码都放在刻度上，如果在同一刻度上，需要放两个游码，则将小的游码挂在大游码的脚钩上。如果样品的相对密度大于1，则单位游码挂在小钩上，待天平保持平衡，记录读数。中文(4)Pouroutthewaterfromtheglasscylinder,washtheglasscylinderandfloathammerwithethanolfirst,andthenrinseseveraltimeswithether,andblowdry.Injectethanolpreadjustedto20℃andplaceitinaconstanttemperaturewaterbathat20℃.Adjustthegamecodesandplacetheminthecorrespondingpositionsformeasurement.Iftwogamecodesneedtobeplacedinthesameposition,hangthesmallergamecodeonthefoothookofthelargergamecode.Trythebiggamecodefirst,MiddleinterceptionprincipleEglish4、读数方法

1号2号3号4号放在第十位10.10.010.001放在第九位0.90.090.0090.0009放在第八位0.80.080.0080.0008……………放在第一位0.10.010.0010.0001四个骑码在各个位置的读数

每台天平有两组骑码，每组有大小不同的四个骑码。与天平配套使用。最大骑码的质量等于玻璃浮锤在20℃水中所排开水的质量。其它骑码各为最大骑码的1/10、1/100、1/1000

中文4、Readingmethod

1号2号3号4号放在第十位10.10.010.001放在第九位0.90.090.0090.0009放在第八位0.80.080.0080.0008……………放在第一位0.10.010.0010.0001Thereadingsoffourgamecodesatvariouspositions

Eachbalancehastwosetsofgamecodes,eachwithfourgamecodesofdifferentsizes,tobeusedinconjunctionwiththebalance.Themaximummassofthegamecodeisequaltothemassofwaterdischargedbytheglassfloathammerinwaterat20℃.Othergamecodesare1/10,1/100,and1/1000ofthemaximumgamecodeEglish举例密度为0.8755中文example:Thereadingis

0.8755Eglish中文5.PrecautionsThebalanceshouldbeadjustedtobalancebeforeuse.Firstusethelargegamecode,thenusethesmallgamecodeAfterthemeasurementiscompleted,allthetravelcodesontheV-shapedgrooveandsmallhookofthecrossbeamshouldberemovedandcannotbeleftontheV-shapedgrooveandsmallhookofthecrossbeam.Whenthebalanceneedstobemoved,easilyseparableparts,components,andcrossbeamsshouldbedisassembledandseparatedtoavoiddamagingtheblade.Eglish1、仪器二、密度计法测定乙醇密度普通密度计附有温度计的糖锤度计密度计是一支中空的玻璃浮柱，上部有标线，下部为一重锤，内装铅粒。中文1、Instrument二、DeterminationofethanoldensityusingdensitymetermethodOrdinarydensitymeterDensitymeterwiththermometerattachedAdensitometerisahollowglassfloatcolumnwithmarkingsonthetopandaheavyhammeronthebottom,containingleadparticles.Eglish2、测定原理-阿基米德定律3、测定方法

将乙醇倾入清洁干燥的玻璃圆筒中，然后将密度计轻轻插入，勿使试样产生气泡，密度计不能碰壁、碰底。待密度计摆动停止后，视线从水平位置观察读数。中文2、Principleofmeasurement-ArchimedesLaw3、Measurementmethod

Pourethanolintoacleananddryglasscylinder,thengentlyinsertthedensitometerinto