(ip) science notes s1 2020

LeeCaiWei103'2020 natureof sciencetheswonkypartsCONPTTGridConsistentWhenobservations/experimentsarerepeatedunderthesameconditions,theresultsarereasonablythesame.ObservableThephenomenonorevidencecanbeobservedbyhumansensesoranextensionofthosesenses.(egmicroscope)NaturalAnaturalcauseornaturallyoccurringmechanismisusedtoexplainhoworwhyaneventhappens.PredictableAccuratepredictionsarebasedononlynaturalcauses,notonpresupposedorassumedinformation.TestableControlledexperimentscanbedesignedtotestthenaturalcauseoftheeventorphenomenon.TentativeExplanationsofthecauseofthephenomenonaresubjectedtochangewhennew(legit)evidenceoccurs. ScientificMethodObservationQuestionHypothesisExperimentAnalysisCommunication thenot soswonkyparts Safetyrules-Safetyrule Reason Wearyourownsafetygoogleswhenusingchemicalsorwhenheating. Protectseyesfromharmfulfumesandchemicalsorliquidthatmayaccidentallypourfromatesttubeduringheating. Donotputsolidwastenorpourconcentratedchemicalsintothesink. Thisistopreventcorrodingthesinkandthechemicalsfromreactingwithoneanotherwhileinthesink.Toalsopreventcloggingupofsink(solidwaste) Donotclosealldoorsandwindowswhenusingthelaboratory. Goodventilationwillpreventtheaccumulationoffumesofgases(fromchemicalreactionsorgassupply)whichmaymakeusfeelunwell.

LeeCaiWei103'2020 Donottasteanychemicals. Toavoidconsumingdangerouschemicalsthatmaybeharmful. Bunsenburner Closedairhole-luminousflameOpenairhole-non-luminousflameLuminousflame-Unsteady-Visible-Yellowcolouredflame Non-luminousflame-Steady-Notvisible-Bluecolouredflame LeaveworkstationforafewminuteswhilehavingBunsenburneron-Turnflamefromnon-luminousflametoluminousbyclosingairhole

LeeCaiWei103'2020 physical propertiesMetal-malleable,goodelectricalconductivity,goodthermalconductivityCeramic-hard,brittle,highmeltingpointGlass-transparent,brittle,poorelectricalconductivityPlastic-donotcorrode/non-biodegradable,poorelectricalconductivity,poorthermalconductivityFibre-elastic,poorelectricalconductivity,poorthermalconductivity Aphysicalpropertyisanypropertythatcanbeobservedormeasured. Aphysicalquantitycanbequantifiedbymeasurementandismadeupofanumericalmagnitudeandaunit. basephysicalquantities SIbaseunits length metre(m) mass kilogram(kg) time second(s) (thesearethecommonones👀 ) prefix howmuchitrepresents mega(M) 10 6 kilo(k) 10 3 centi(c) 10 -2 milli(m) 10 -3 UncertaintyofareadingHalfofsmallestdivision:e.g.thermometer,measuringcylinder(alsoprecision) Density=mass/volume averagedensity=totalmass/totalvolume

LeeCaiWei103'2020 chemical compositionElements● puresubstancesthatcannotbebrokendownfurtherintosimplersubstancesusingchemicalprocesses● containsonlyonetypeofatom● metalsfromperiodictablegrp1-3● metalloids● non-metalsfromgrp5-8● puresomeltandboilatfixedtemp Compounds● aremadeoftwoormoretypesofatomschemicallycombinedtogether● hasafixedproportionofeachelementbymass● formedfromelementsbychemicalchange● puresomeltandboilatfixedtemp● propertiesaredifferentfromelements● canbeseparatedbychemicalmethodsthosoyay:) Mixtures● Solutions- aremixturesoftwoormoresubstanceshomogeneouslymixed,usuallydissolved.- Formedbydissolvingsoluteintosolvent ● Suspension- aremixturesthathavesomesolidorliquidthatisinsolubleinliquidorgas- heterogeneousmixtures- insolubleparticlespreventlightfrompassingthrough;willsettletobottomaftersometime ● haveavariableproportionofeachelement● meltandboiloverarangeoftemperatures● propertiesaresimilartothecombinationofelements/compoundsfoundinmixture● canbeseparatedusingseparationtechniques Solubility RateofDissolving Whatisit? themaximummassofasolutethatcandissolveinafixedvolumeofsolventatacertaintemperature themassofasolutethatcandissolveinafixedvolumeofsolventinafixedamountoftime Affectingfactors - Natureofsolvent- Natureofsolute- Temperature - Temperature- Sizeofsoluteparticles- Rateofmixing basicallysolubilityisagainst temp, rateof dissolvingisagainst time

LeeCaiWei103'2020 separationtechniques Magneticattraction- Basisofseparation:magneticornon-magneticmaterial- Substancesintheworldcanbemagnetic(canbeattractedbymagnets)ornon-magnetic.Ironandsteel(whichcontainsiron)arebothmagnetic.- Amagnetcanbeusedtoseparateamagneticmaterialfromanon-magneticmaterial.- Techniquedoesnotworkforseparatingmixtureswheremorethanonesubstanceismagnetic- Dailyapplication:Garbageseparation apicbcwhynot Filtration- Basisofseparation:solubility(liquidandinsolublesolidmixture)- Cannotbeusedforliquidandsolublesolidmixtures- Asolidthatisnotsolubleinaliquidcanbeseparatedfromitbytheprocessof filtration

LeeCaiWei103'2020 morepicsbcwhynot Evaporation- Basisofseparation:boilingpoint(solutions)- Asolidthatdissolvesinasolventtoformasolutioncannotbeseparatedbyevaporation.Thesolventhastobeevaporatedawaybeforethesolutecanberecoveredasanundissolvedsolid.- Techniquecannotbeusedforinsolublesolidinliquidsolvent/solublesolidinliquidsolventthatdecomposesunderhighheat. - Distillation- Basisofseparation:boilingpointsthatarefarapart- Asolventcanbeseparatedfromtheoriginalsolutionbydistillation.- Thedistillate(liquidthatiscollected)thatiscollectedhasthelowerboilingpointandisusuallythesolvent.

LeeCaiWei103'2020 - Techniquecannotbeusedformiscibleliquidmixtureswhoseboilingpointsareveryclosetoeachother ● Boilingchipsareaddedtoensuresmoothboiling.● Thecomponentwiththelowerboilingpointwillturnintovapourandriseupwards.● Thethermometer’sbulbmustbebesidethesidearmtoensurethattheboilingpointofthesubstancebeingmeasuredisdistilled.● Thevapourwillthenenterthecondenser.● Thecondensermustslopedownwardssothattheliquidcondensesinsideandrunsdownwardsintotheconicalflask.● Inthecondenser,coldrunningwaterentersfromthebottomsothatthewaterjacketwillbecompletelyfilledwithwaterformoreefficientcooling. FractionalDistillation- Basisofseparation:boilingpointsofliquids(inmiscibleliquidmixtures)thataredifferentbutveryclosetoeachother- Miscibleliquidscanbeseparatedastheywillboilatdifferenttemperaturesandcanbecollectedaccordingly.- Thefirstdistillate(liquidthatiscollected)istheliquidwiththelowestboilingpoint.

LeeCaiWei103'2020 - Dailyapplication:Oilrefining ● Afractionatingcolumnhasmanyglassbeadstoprovidealargersurfaceareaforvapourtocondenseon.● Theliquidwiththelowestboilingpointwillboilanddistilloverfirst.● Otherliquidswithhigherboilingpointsthathappentoformvapourwillbecondensedinthefractionatingcolumnandfallbackdown.● Whenallofthefirstliquidhasbeendistilled,heatingcontinuestothenextboilingpoint,untilthenextliquiddistillsover. Chromatography- Basisofseparation:solubilityinsolvents(soluteswithdifferentsolubilities)- Amixturecanhaveitscomponentsseparatedbasedonthesolubilityofthesolutesinthechosensolvent.

LeeCaiWei103'2020 Rf value=𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒𝑡𝑟𝑎𝑣𝑒𝑙𝑙𝑒𝑑𝑏𝑦𝑐𝑜𝑚𝑝𝑜𝑛𝑒𝑛𝑡 𝑨𝑓𝑟𝑜𝑚𝑠𝑡𝑎𝑟𝑡 𝑙𝑖𝑛𝑒/ 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒𝑡𝑟𝑎𝑣𝑒𝑙𝑙𝑒𝑑𝑏𝑦𝑠𝑜𝑙𝑣𝑒𝑛𝑡 𝑓𝑟𝑜𝑚𝑠𝑡𝑎𝑟𝑡line ● Thestartinglevelofthesolventmustbelowerthanthestartlinedrawn,becausethesolventisabsorbedupwardsbycapillaryaction.● Thestartlineisdrawninpencilasitismadeofgraphiteandwillnotdissolveinthesolvent.● Thecomponentswillmovealongwiththesolventasitmovesupthepaper.Themoresolubleoneswillmovefurtherupwiththesolvent. Crystallisation- Basisofseparation:Boilingpoint(solutions)- Requiressolublesolidinliquidsolvent- Ifsolublesoliddecomposesunderhighheat,canonlyusecrystallisation. Separationfunnel- Basisofseparation:immiscibleliquids

LeeCaiWei103'2020 - Doesnotworkformiscibleliquids(duh!)