On food and cooking the science and lore of the kitchen ( PDFDrive ) 1532
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bondonceit’sformed.Whentheatomsina
moleculeareheatedupsotheymovewiththe
samekineticenergythattheyhadreleased
whentheybondedtoeachother,thenthose
bondsbegintobreakapart,andthemolecule
beginstoreactandchange.
Thestrongcovalentbondstypicalofour
majorfoodmolecules—proteins,
carbohydrates,fats—arebrokenbyabout
100timestheaveragekineticenergyof
moleculesatroomtemperature.Thismeans
thattheybreakveryrarelyatroom
temperature,anddon’tchangeatasignificant
rateuntilweheatthem.Theweaker,
temporaryhydrogenandvanderWaalsbonds
betweenmoleculesareconstantlybeing
brokenandre-formedatroomtemperature,
andthiswelterofactivityincreasesasthe
temperaturerises.Thisiswhyfatsmeltand
becomethinnerinconsistencyasweheat
them:theenergyoftheirmotionincreasingly
overpowerstheforcesattractingthemtoeach
other.
ThePhasesofMatter
Inoureverydaylife,weencountermatterin
threedifferentstates,orphases(theword
comesfromtheGreekfor“appearance”or
“manifestation”).Thesestatesarethesolid
phase,theliquidphase,andthegasphase.The
temperaturesatwhichamaterialmelts—
changesfromsolidtoliquid—andboils—
changesfromliquidtogas—aredetermined
bythebondingforcesamongtheatomsor
molecules.Thestrongerthebonds,themore
energyneededtoovercomethem,andsothe
higherthetemperatureatwhichthematerial
shiftsfromonephasetoanother.Duringthat
shift,alltheheataddedtothematerialgoes
intocompletingthephasechange.The
temperatureofasolid-liquidmixwillremain
fairlyconstantuntilallthesolidhasmelted.
Similarly,thetemperatureofapotofboiling
