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1、10级应用化学（2）班郑禄春B2010063224Lessen24ChemicalReactionsConservationofmassandenergy（质量与能量守恒）Twoconservationlaws（定律）applytoallchemicalreactions:Energycanneitherbecreatednordestroyed,andmattercanneitherbecreatednordestroyed.Thustheatomstakingpartinachemicalreactionmayberearranged,butalltheatomsp
2、resentinthereactantsmustalsobepresentintheproducts,andthetotalmassofthereactantsmustequalthetotalmassoftheproducts.化学反应质量守恒和能量守恒两个守恒定律(定律)适用于所有的化学反应:能量既不能创造也不能消灭,物质也不能创造也不能消灭。因此原子参与化学反应可能重新安排,但所有的原子出现在反应物必须包含在产品,反应物的总质量必须等于生产物的总质量。Whatisachemicalreaction?Achemicalreactionoccurswhensubsta
3、nces(thereactants)collide(碰撞)withenoughenergytorearrangetoformdifferentcompounds(theproducts).Thechangeinenergythatoccurswhenareactiontakeplaceisdescribedbythermodynamics(热力学）andtherateorspeedatwhichareactionoccursisdescribedbykinetics(动力学).Reactionsinwhichthereactantsandproductscoexista
4、reconsideredtobeinequilibrium(处于平衡).Achemicalequationconsistsofthechemicalformula（化学式）ofthereactants,andthechemicalformulaoftheproducts.Thetwoareseparatedbyan→usuallyreadas“yields”andeachchemicalformulaisseparatedfromothersbyaplussign(加号).Sometimesatriangleisdrawnoverthearrowsymboltodeno
5、teenergymustbeaddedtothesubstancesforthereactiontobegin.Eachchemicalformulamaybeprecededbyascalar(数量的)coefficientindicatingtheproportion(比例)ofthatsubstancenecessarytoproducethereactioninformula.Forinstance,theformulafortheburningofmethane(CH4+2O2→CO2+2H2O)indicatesthattwiceasmuchO2asCH4i
6、sneeded,andwhentheyreact,twiceasmuchH2OasCO2willbeproduced.Thisisbecauseduringthereaction,eachatomofcarbonneedsexactlytwoatomsofoxygentocombinewith,toproducetheCO2,andeverytwoatomsofhydrogenneedanatomofoxygentocombinewithtoproducetheH2O.Iftheproportionsofthereactantsarenotrespected,whent
7、heyareforcedtoreact,eithernotallofthesubstanceusedwillparticipateinthereaction,orthereactionthatwilltakeplacewillbedifferentfromtheonenotedintheequation..什么是化学反应一个化学反应发生在物质(反应物)碰撞有足够的能量去重新排列,形成不同的化合物(产品)。当反应发生时能量发生变化由热力学描述，利率或速度进行反应发生是由动力学描述。反应中,反应物和生成物共存被认为是处于平衡。一个化学方程式包
