爱德思化学复习大纲A2-U4-Topic-12-Entropy-and-Energetics.pdfVIP

EdexcelIALChemistryRevisionGuildeMeishaAcademybyHaileybury—King

Topic12EntropyandEnergetics

--King

考点一：Introductiontoentropy.

understandthat,sinceendothermicreactionscanoccurspontaneouslyatroomtemperature,enthalpychangesalonedo

12.1

notcontrolwhetherreactionsoccur

understandentropyasameasureofdisorderofasystemintermsoftherandom

12.2

dispersalofmoleculesandofenergyquantabetweenmolecules

understandthattheentropyofasubstanceincreaseswithtemperature,thatentropyincreasesassolid→liquid→gasand

12.3

thatperfectcrystalsatzerokelvinhavezeroentropy

beabletointerpretthenaturaldirectionofchangeasbeinginthedirectionofincreasingtotalentropy(positiveentropy

12.4

change),includinggasesspreadspontaneouslythrougharoom

1,Mostchemicalreactionsareexothermic,sincesubstanceswithlessenergy(energeticallystable)isfavourable.Butnotallthe

spontaneousreactionsareexothermic.Thedrivingforcesare（-enthalpy;H-entropy;S）

2,Entropy(熵)isameasureofthedisorder/randomnessofasystem.Themoredisorderedtheparticlesare,thehighertheentropyis.

--Entropyofasubstanceincreaseswithnumberofmolecules.

解释：thehighernumberofmolecules,thehighernumberofpossiblearrangements,

--Entropyofasubstanceincreaseswithtemperature.

解释：thehigherthetemperature,themoreenergyasubstancehas.Themorewaystodistributeenergy.

Entropy:solid→liquid→gas

ThirdLawofThermodynamics(热力学第三定律)--Aperfectcrystalsatzerokelvinhavezeroentrop