5. 基础知识之文章阅读2-

1第5讲化学化工专业基础知识3BasicKnowledgeofChemistryandChemicalEngineering3SpecilaizedEnglishforChemistryandEngineeringLesson3LaboratoryTechniques5.Heatingliquids(1)TestTube.Thetesttubeshouldbenomorethan1/3full.Placeagentleflameatthetopoftheliquidnotatitsbase.Movethetesttubeinandoutoftheflamewhilegentlyswirlingitscontents.Neverpointthetesttubetowardanyone.（1）试管.试管盛装的液体应不超过体积1/3.把火焰置于液体的顶端而不是底部加热。在火焰的内外移动试管，同时缓慢地旋转试管中溶液。千万不要将试管对着任何人。(2)AHotWaterBath.Asmallquantityofsolutionthatneedstobeheatedtoaconstanttemperaturecanbeplacedinahotwaterbath.Ifthesolutionisinabeakerthenplaceitinalargerbeakerfilledwithwater,andheattothedesiredtemperature.（2）热水浴需要加热至固定温度的少量溶液可将其置于热水浴中。如果溶液是装在烧杯中，则将其放入一个更大的装满水的烧杯中，然后加热至所需的温度。6.Glassworking(1)CuttingGlassTubing.Makeascratchacrosstheglasstubingatthedesiredlocationwithasinglestrokeofatriangularfile.Placeadropofwateronthescratchwithyourfinger.6.玻璃加工（1）切割玻璃管用三角锉在玻璃管所需长度位置制造一道刮痕。用手指沾一滴水涂在刮痕上。Thetubingmustalwaysbeheldinatowelwhilepressureisbeingappliedtopreventinjurytothehands.Placeboththumbsclosetogetheronthesideofthetubingoppositethescratch,andsnapthetubinginadirectionawayfromyouandothersagainstthepressureofthethumbs.当用力时，玻璃管必须置于毛巾中以免伤害到手。将两个拇指贴紧与刮痕相反的玻璃管一侧，然后拇指朝自己或别人相反的方向用力折断管子。(2)FirePolishingGlassTubing.Alledgesofglasstubingmustbefire-polishedtoroundoffthesharpedges.Holdthesharpedgesofthetubingatanangleintheflameandrotatethetubinguntilabrightyellowcolorisimpartedtotheflame.Besuretoavoidoverheatingtheglasstubing.（2）火抛光玻璃管所有的玻璃管边缘都必须火抛光以磨光其毛刺。将玻璃管毛刺的一边倾斜地置于火焰上，然后旋转玻璃管直到出现明亮黄色火焰。一定要避免过度加热玻璃管。(3)BendingGlassTubing.Attachawingtoptotheburnertospreadtheflame.Holdapieceoftubinghorizontallyintheupperportionoftheflameandslowlyrotatetoensureuniformheating.Continuerotationofthetubinguntilitbecomessoft.Smoothlybendtheglasstubingandallowittocoolonafireresistantsurface.（3）弯曲玻璃管连接一个火焰扩张器到灯头来扩散火焰。将管子一段置于火焰上部并缓慢地转动以确保受热均匀。继续旋转管子直到其变软。然后平滑地弯曲管子并将其置于耐高温表面冷却。7.TestingGasesforOdorAneducatednoseisanimportantandusefulassettohaveinthelaboratory.Itmustbeusedwithcautionbecausesomegasesaretoxicorjustirritant.Neverholdyournosedirectlyoverthevesselfromwhichthegasiscomingfrom.Rather,fansomeofthevaporstowardyournose.7.测试气体气味一个灵敏的鼻子在实验室是一个很重要和有用的优势。必须小心因为有些气体是有毒或者有刺激性的。千万不要将鼻子直接靠近释放气体的容器。正确地做法是，用手向鼻子扇一些气化物。8.UsingamagneticstirrerAmagneticstirrerishelpfulfordissolvingsolidsinliquids.Whilethereareseveraldifferentstyles,allwillatleasthaveabasewithaspeed-controlledspinningmagnetinsideandanexternalstirringbar.8.使用磁力搅拌器磁力搅拌器对于溶解固体到液体中是很有帮助的。有几种不同的类型，它们每一种都有一个基底，内部有一个控制速度的旋转磁铁和外面有一个搅拌子。Thestirringbarisplacedintoaflaskorbeakerbygentlyslidingitalongthewallofthecontainer.Topreventbreakage,donotdropthebarontothebottomofthecontainer.Placethecontaineronthestirrerbaseandturnthespeedcontrolknobtoitslowestsetting.搅拌子放于烧瓶或烧杯中可缓慢地沿着容器的内壁滑动。为了防止破裂，不要将搅拌子丢入容器底部。将容器放在搅拌器平台上，转动速度控制旋纽到最低档。Usejustenoughspeedtostartthebarturninginthecontainer.Thepicturehereshowsthe“vortex”thatformsinsidethecontainer.Bepatient,thebarmight“hop”atexcessspeeds,causingsplashing.采用足够速度使容器内磁子开始旋转。这幅图展示了在容器内形成的涡流。必须有耐心的是，磁子可能会过速跳跃，引起飞溅。Ifusingexactvolumes,aswithavolumetricflask,besuretakethemeasurementsbeforeaddingthestirringbar.Whenstirringiscompleted,keepthestirringbarinthecontainerby“decanting”theliquidintoanothercontainer.Besuretocarefullywashtheoriginalcontainerandthestirringbar.如果使用精密容器，比如容量瓶，一定要在测量之前加一个搅拌子。当搅拌完成时，倾倒溶液至另一个容器内后，将搅拌子留在原容器内。一定要仔细地清洗原容器和搅拌子。9.CleanglasswareThekeytocleaningisdoingitatimelymanner;lettingdirtyglasswaresitforlongperiodsoftimeresultsinahardercleaningjob.Alsotakeaminutetoseparateyourglasswareintoagroupwhichrequiresahigherdegreeofcleaningandonethatdoesnot.9.清洗玻璃器皿清洗的关键就是及时，让脏的玻璃器皿放置过久会导致清洗工作更困难。需要花费一点时间来将玻璃器皿分类，分成哪些需要高度清洗，哪些不需要。Disassembleyourapparatusassoonaspossibleafteryouarefinishedwithit.Removeallstopcocksandstoppersfromadditionfunnels,separatoryfunnelsandthelike.Groundglassstopcocksandstopperswillfreezeinplaceifcertainreactants(e.g.,bases)wereusedinthem.当完成实验时尽可能快的拆开仪器。把加料漏斗，分离漏斗和类似仪器中所有的开关和活塞拧开。如果实验中使用了特殊试剂（如碱），磨口玻璃活塞和开关就会封死。Triplerinseallsurfaceswithanappropriatesolventtoremovetracesofsolventsandreactionmixtures,placetheseintheappropriatewastecontainer.使用合适的溶剂冲洗所有仪器表面三次以去除溶剂和反应混合物的残留，将废液倒入合适的废液桶中。Graduatedcylinders,beakers,Erlenmeyerflasks,buretsandpipettesthatwereonlyusedtodispenseorstorereagentsgenerallyonlyneedtobetriple-rinsedwithacompatiblesolventfollowedbytapwaterandafinalDIwaterrinse,ifdesired.那些仅用于分配或储存试剂的量筒、烧杯、锥形瓶、滴定管和移液管一般仅需使用相容性溶剂，自来水和去离子水冲洗三次。Airdryonadryingrack.Insomecasesyoumayneedtobemorethorough,asdescribedbelow.放入干燥器中风干。有些情况下，你可能需要更彻底地清洗，如下所述。Büchnerfunnelsshouldberinsedwithanappropriatesolventtoremovesubstancesthatareclingingtothem.ThenusetapwaterandDIwaterrinsesandairdry.布氏漏斗应该使用合适的溶剂清洗以去除依附在表面的物质。然后使用自来水和去离子水冲洗并风干。10.UsingafumehoodThefumehoodisasafetyglass-frontcabinetwithanexhaustfan.Itisusedforexperimentsknowntoproducenoxiousfumesorsmoke.Dothefollowingtoperformanexperimentinthehood:10.使用通风厨通风厨是一种安全的前面玻璃并带有排气扇的厨柜。它被用于会产生有毒烟雾的实验。在通风厨中完成一个实验应按以下步骤做：(1)Raisethedoorofthehood(2)Turnonthelightandsetupt