The chemistry of lifeWord文件下载.docx
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The chemistry of lifeWord文件下载.docx
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GreetingsfromSpain,
Silvia
Howsoapcleans?
Therearesubstanceswhichcanbedissolvedinwater(saltforexample),andothersthatcan'
t(forexampleoil).Waterandoildon'
tmixtogether,soifwetrytocleananoilystainfromaclothorfromtheskin,waterisnotenough.Weneedsoap.
Soapisformedbymoleculeswitha"
head"
whichlikeswater(hydrophilic)andalongchainwhichhatesit(hydrophobic).
Becauseofthisdualism,soapmoleculesactlikeadiplomat,improvingtherelationshipbetweenwaterandoil.How?
Whensoapisaddedtothewater,thehydrophilicheadsofitsmoleculesstayintothewater(theylikeit!
),whilethelonghydrophobicchainsjointheoilparticlesandremaininwards(escapingfromthewater).Inthatway,theyformcirculargroupsnamedmicellas,withtheoilymaterialabsorbedinsideandtrapped.
Anemulsionofoilinwateristhenformed,thismeansthattheoilparticlesbecomesuspendedanddispersedintothewater.Thus,thoseoilparticlesareliberatedfromtheclothortheskin,andtheemulsionistakenawaywiththerinsing.
Insummary,soapcleansbyactingasanemulsifier.Itallowsoilandwatertomixsothatoilygrimecanberemovedduringrinsing.Therearemorethingsinvolvedinthisprocess,suchasforinstancechangesinthesuperficialtensionofwater,butthisisthegeneralidea.
Vegetablesandcolours-Part1
Whitelightfromthesuncontainsallthewavelengths,butwhenitimpactsonanobjectsomeofitswavelenghtsareabsorbedandsomereflected.Anobjectiscolouredbecauseofthelightthatitreflects.Forexampleredobjectsreflect'
red'
light,whichislightwithalongwavelength.Manyvegetablesandfruitsarestronglycolouredbecausetheycontainanespecialkindofchemicalcompoundsnamedcarotenoids.Thesecompoundshaveanareacalledchoromophore,whichabsorbsandgivesoffparticularwavelengthsoflight,generatingthecolourthatwethenperceive.
Thechromophoreisformedbyasequenceoflinearcarbon-carbondoublebonds(representedasC=C),muchstrongerthansimplebonds(representedasC-C),sotheatomsremainclosertoeachother.Ingeneral,it'
snecessaryatleastsevenlinearconjugateddoublebondsforacarotenoidtoproduceacolour.Besides,thebiggerthenumberofbondsconjugated,thebiggerthewavelengthofthelightabsorbedandalsothemoreredthevegetable,asyoucanseeinthispictureofthelightspectrum:
Thetomatoisredbecauseofthecarotenoidlycopene,whichcontains11conjugatedcarbon-carbondoublebonds.Youcancountthesebondsinthepicturebelow,theyareselectedinred(theatomcarbonsareomitted,onlythebondsareshown).Thiscompoundisgeneratedbytheplanttoprotectitselffromtheairoxidation.Soit'
sagoodantioxidantusefulforustoo,protectingourcellsagainsttheactionoffreeradicals(potentoxidants),whichareoneofthemainresponsiblesofcardiovasculardiseases,cancerandaging.
(SeethecontinuationinPart2below)
Vegetablesandcolour-Part2
Thepigmentpresentincarrotsisthebetacarotene,with9linearconjugateddoublebonds,lessthaninlycopenesotheyarenoredbutorange(smallerwavelengththanred,checkitinthespectrumpicture).Thiscompoundisalsoapotentantioxidantandbesidesit'
stransformedinourbodyintovitaminA,veryimportantforthemaintenanceofhealthyskin,goodvisionandarobustinmunesystem.
Spinachs,parsleyandplantsingeneralaregreenbecausetheycontainchlorophyll,apigmentwhichenablestheplanttocarryonphotosynthesis,transformingsolarenergyandcarbondioxideintochemicalenergyintheformofcarbohydratesandoxygen.Thisisaprocessessentialforlife.
Asyoucanseeinthepicbelow,thestructureofchlorophyllisverycomplicated,solet'
ssimpysaythatitcontainsabigringwithamagnesiumatominthecenter.Curiously,thestructureofhemoglobine(thecarrierofoxygeninourblood)isprettysimilartochlorophyll,thoughithasanatomofironinsteadofmagnesiuminitscenter.
Thechlorophyllmaskstheothercoloursinvegetablesandasitsamountdecreasestherestofcoloursbecomeevident.Thisexplainsforexamplewhytomatoesareinitiallygreenandthenbecomeredwhentheyripen.
ThisisanexampleofhowChemistryiseverywhere,sometimesmoreevident,andsometimesmuchless:
-).
Myguestbook
Please,leaveyourcommentsaboutthislenshere
Iinviteyoutoleaveyouropinionaboutthislensinthisspace,clickingonthe"
Submityourownblurb"
linkbelow.Youcanalsoaskanyquestionaboutchemistryofdailylife.
I'
dlovetoreadyourcomments!
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∙Reply
mskaylayOct11,2010@10:
15am|delete
Ireallyenjoyreadingyourlenstoday,keepupthegoodwork.
SycroOct9,2010@3:
24pm|delete
Hey
Itriedsooooooooomanytreatmentsforsweatypalmsovertheyears,noneofthemreallyworkedorwerejustashorttermsolution.Howeverwhenifoundnaturalholistictreatments,iknewi'
dfoundthecure.
Thanks
sweatypalms
WriterBuzzOct6,2010@5:
42am|delete
Yourlensisgreat.Veryinformative.Ilikedyourlenswithathumbsup.
painkookOct3,2010@9:
37pm|delete
Thumbsup!
Greatlens...veryinformative.Ihavenoideawhywheniwassearchingforbrothertonerandthispoppedupingoogle.I'
vebookmarkedthispagetodel.icio.us.Anyway,keepthegreatwork!
alyonamooreAug18,2010@2:
45am|delete
Wonderfulwritingandveryusefulinformation.Thankyou.Imightwanttoaddthatmaintainingabloodpressurechartwillhelpyoutakecontroloveryourheartandensurehealthybloodpressure.
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Whymealsarecookedfasterinapressurecooker?
Apressurecookerislikeanyotherpotbutwithamoreelaboratedlidthatsealsthepotcompletely.Whenyouheatwaterinsidethepotitboilsandthesteamcannotescape,soitremainsinsideandstartstobuilduppressure.Underpressure,cookingtemperaturesraisemuchhigherthanundernormalconditions(higherthantheboilingpointofwater,thatis100º
C),sothenthefoodiscookedmuchfaster.Cookingtimescanbereducedbyafactorofthreeorfour.
Besidescookingfaster,thismethodretainsmorenutrientspresentinthefoodthanothermethods.Anddidyouknowthatapressurecookerisoftenusedbymountainclimbers?
Withoutit,waterboilsoffbeforereaching100º
Cbecauseoftheloweratmosphericpressureathighaltitudes,leavingthefoodimproperlycooked.
Whydoonionsmakeyoucry?
Whohasnevercriedwhilecuttinganonion?
(well,apartfromthosewhohavenevercutonehehehe).Thisisalittleexplanationineasyterms.
Insidetheonioncellstherearesomechemicalcompoundsthatcontainsulfur.Whenyoucutanonionitscellsarebrokenandthosechemicalcompoundsthenundergoareactionthattransformsthemintoamorevolatilesulfuredproducts,whicharereleasedintotheair.
Thesesulfuredcompoundsreactwiththemoistureinyoureyesformingsulfuricacid,whichproducesaburningsensation.Thenerveendingsinyoureyesareverysensitiveandsotheypickuponthisirritation.Thebrainreactsbytellingyourtearductstoproducemorewater,todilutetheirritatingacid.Soyoucrytokeepyoureyesprotectedfromtheacid.
Therearesometrickstomakeonion-dicinglessproblematic:
-Choptheonionundercoldwater.Thevolatilesulfuredcompoundswillbereleasedbutthentheyreactwiththewater,insteadofreachingyoureyes.
-Youcanfreezetheonionfor10minutesbeforecuttingit.Thecoldtemperatureoftheonionwillslowdownthechemicalreactionwhichformsthevolatilesulfuredcompunds.
Howtomakeinvisibleinkathome?
Thisisafunnyexperimenttodowithkidsathome.
Youcanplaywithyourkidsathomemakinginvisibleinkwithbasicproductsthatyouhaveinthekitchen.Therearemanymethodstomakeinvisibleink.Thesearesomeoftheeasiestones:
1)Lemonjuicemethod
-Ingredients:
justlemonjuice.
Writeyourmessageonapieceofpaperwithabrushortootpickembeddedinlemonjuice.Letitdrycompletely.
Toreadthemessageheatthepaperforawhile(forinstanceholditclosetoalightbulb)untilthewordsbecomevisible.Warning:
donotholdpapertooclosetotheheatandbecarefulnottoletitgettoohot!
-Chemicalexplanation:
Lemonjuiceisamildacidthatweakensthepaperuponcontact.Sowhenyouheatthepaperthepartwiththejuiceburnsbeforetherestmakingyourmessagevisible.
2)Bakingsodamethod
bakingsodaandwaterinsameamount(forinstance30mLofeach).
Mixthemanduseatoothpickorbrushtowriteonapieceofpaper.Waituntilitdriescompletely.
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