glass melting - university of washington：玻璃熔化-华盛顿大学

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1、MSTGlassMeltingMTISummer1999Page1408/05/21GlassMelting(Reference:BattellePNNLMSTHandbook,U.S.DepartmentofEnergy,PacificNorthwestLaboratory)BackgroundInformation:MolePercentWhenbatchingglasses,youneedtoperformcalculationstofigureouttheweightsofvariouschemicalsneeded.Theconcep

2、tofthe“mole”needstobedevelopedbeforethesecalculationsaredone.Thefollowingbackgroundinformationwillhelpyouunderstandthemole.Threewaysofbuyingthingscommonlyexist:volume(gallonsofgasoline),number(dozeneggs),andweight(poundsoforanges).Volumeisfairlygoodforliquids,anditisconven

3、ient,butitisn’tveryreliableforsolidsbecauseofsuchthingsasairgapsandirregularities.Also,volumechangeswithheatandpressure.Numberisfineforregularthings,butitisunfairtosellapplesbythenumbersincesomearelargeandsomearesmall.(Someofushavethesamefeelingsaboutshoesandshirtstoo!)Mostt

4、hingsaresoldbyweight,althoughtheseareusuallypre-packaged,sowereallybuythembythenumberofpackages.Mostofthethingswebuybyweightare“bulk”items.Afewexamplesarebananas,grapes,candyatacandystore,coal,andnails.Oneofthereasonsnailsaresoldbyweightisbecausesmalloneswouldbetooboringandt

5、imeconsumingtocounteachtimetheyaresold.Ifthisweredone,thepricewouldalsorise.Ingeneral,thingsaremeasuredbyweighttodeterminetheirnumberifthingsaretoosmalltobeconvenientlyhandled.Twoformulasthatareusedare:Theseideasandformulasarealsousedwithchemicals.Atomscombinetoformchemical

6、compounds.Forexample,experimentsenableustoknowthattwoatomsofhydrogencombinewithoneatomofoxygentoformonemoleculeofwater(H20).Unfortunately,atomsarefartoosmalltobecounted.Therefore,weuseweightandtheaboveformulastodeterminenumbersofatoms.Becausetwoatomsofhydrogencombinewithonea

7、tomofoxygentoformonemoleculeofwater,itfollowsthattwodozenatomsofhydrogencombineswithonedozenatomsofoxygentoformonedozenmoleculesofwater.Also,200atomsofhydrogencombinewith100atomsofoxygentoform100moleculesofwater.Atomsarefartoosmalltoseehundreds,millions,oreventrillionsofthe

8、m;so,anewnumbercalleda“mole”isusedwithatoms.Itishuge!Amoleis602,000,000,000