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1、MatterinYourWorld4.1NotesMatterisanymaterialthatoccupiesspaceandhasmass.Matterincludesallsolids,liquidsandgases.Theseformsofmatterhavedifferentcharacteristics.Thecharacteristicsthatareusedtodescribematterarecalledproperties.Everymaterialhasitsownsetofproperties.Undernormal
2、conditions,waterfreezesat0oCandboilsat100oC,itisalsoclear,colourless,odourlessliquid.Wheneveryouseeamaterialthathasmorethanonesetofproperties,youknowthatitisamixture.AmixturecontainsmorethanonekindofmatterAmixturecontainsmorethanonekindofmattercombinedinsuchawaythateachkee
3、psitsownproperties.Mixturesthataremadeupofpartsthatcanbeseenarecalledheterogeneous.Heterogeneousmeansmadeupofparts,ormixed.Materialsthathaveonlyonesetofpropertiesarecalledhomogeneous.Homogeneousmeansthateverypartofthematerialisthesame.Anexampleofheterogeneousmaterialisonpa
4、ge103inthetextbook.(Cementorconcreteisheterogeneous.CheckYourUnderstanding4.11.Somepropertiesofwaterareclear,colourless,ordourless,freezesat0oC,boilsat100oC,dissolvesmanysubstances.Somepropertiesforglassaretransparent,hard,durable,breakseasily,inflexibleSomepropertiesforst
5、eelareopaque,heavy,strong,willrustandcorrode,inflexible.2.Youcannotdistinguishbetweenthedifferentcomponentsinahomogeneousmixture,sothemixtureappearsthesameallover.Ahetergeneousmixturedoesnotappearthesameallover,andthedifferentcomponentsarevisible.3.(answerswillvary)4.a)The
6、waterinoneriverwillhaveonesetofproperties.b)Riverwaterisheterogeneous.Thebrowncolourisriverwaterindicatesthepresenceofdirtparticles.5.(studentsanswerswillvarybuttheyshouldrealizethatmostmaterialsareheterogeneous)4.2NotesWhatisamixture?Anythingwithtwodistinctsetsofpropertie
7、smustbeamixtureofatleasttwomaterials.Whenamixture'sdifferentpartscanbeidentifiedthiseasily,themixtureisusuallycalledamechanicalmixture.Homogeneousmixturesiscalledasolution.Solutionsareeverywhere.TwothirdsofEarthiscoveredwithaliquidsolution-thesaltywateroftheoceans.Earthiss
8、urroundedbyagasslutionthatwecallair-ahomogeneousmixtureofoxygen,nitrogen,andothergases.Th
