OneMondaymorning,Paulandhisclassmateswereinsciencelaboratoryfortheirpracticalchemistrylesson.Thestudentsweregoingtoworkinpairstodoanexperiment.Beforetheybegan,theteachergavethemthisdescriptionofthedifferentstagesoftheexperiment. Stage1:Preparetheequipment:atesttube,acrucible,aBunsenburnerandtongs. Stage2:Weigh5gramsofbakingsoda(sodiumbicarbonate)andputitinacrucible. Stage3:Heat10mlofhydrochloricacid(盐酸)inatesttube. Stage4:Pourthewarmacidontothebakingsodaandcontinuetoheatthemixture. Result:Theacidreactswiththebicarbonate(碳酸氢盐)toformwater,carbondioxidegasandsalt.Thehotterthemixture,thequickerthereaction.Continuetoheatthemixtureuntilthewaterevaporates,leavingthesaltinthecrucible. Paulandhispartnerfollowedtheinstructionsandsetuptheirequipment.Paulwenttothecupboardtogetabottleofhydrochloricacid.Hefoundthattherewasonlyonebottleinthecupboardsohetookthat.TherewasnolabelonthebottleandPauldidn’tcheckwiththeteacherifitwastherightsolution. Hemeasuredtheliquidandpoureditintoatesttube.Usingtongstoholdthetesttube,heheateditovertheBunsenburner.That’swhenthingsstartedtogowrong.Theliquidinthetesttubewasnothydrochloricacid.Whenitwasheated,itformedathickcloudofwhitegas.Soontheroomwasfullofthisstrongsmellingwhitegas. Allthestudentsstartedcoughingandtheireyeshurt.Theteacherimmediatelyopenedthewindowsandorderedthestudentstoleavethelaboratoryatonce.Sherealizedthattheliquidwasacrylamide(丙烯酰胺)andthatitispoisonous. Fortunately,nobodywasinjuredintheincident.However,ittaughtthestudentsandtheteacheragoodlesson. 小题1:Whatlessondidtheincidentteachthestudentsandtheteacher? |