文档介绍：1０级应用化学（2）班 郑禄春 B20１006３22４
Lｅｓsｅｎ 2４ Ｃｈeｍｉcal Reaｃtiｏｎs
Coｎservatｉoｎ of mａsｓ ａｎd enｅｒgy（质量与能量守恒）
Two consｅrｖation laws（定律） appｌy to all ｃｈeｍicａｌ reactｉoｎs: Energy can neithｅｒ be ｃreateｄ nｏr desｔroyed， and matter ｃan ｎｅither bｅ ｃｒeated nｏr ｄestrｏyed。 Thｕs tｈｅ atoms takｉｎg ｐart in a ｃheｍｉcal rｅaｃｔiｏn may be rearranged， bｕt all the aｔoms ｐｒｅｓent in ｔhe reactants mｕst ａlso ｂe presｅnt in the ｐｒoｄucts， aｎd ｔhｅ toｔaｌ masｓ of ｔｈｅ reａcｔａnｔs ｍusｔ equａl tｈe totaｌ mａｓs of thｅ prodｕｃtｓ。
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。
Wｈａt is a cｈｅmｉcａl rｅactｉon？
A cｈemｉcal reａｃｔｉｏn oｃｃurｓ whｅn ｓubstances (the reacｔanｔs) ｃolｌiｄe (碰撞） ｗith enough enｅrｇy ｔo rearrange ｔo ｆｏrm diｆferent ｃomｐounｄs （the proｄucts). Tｈe cｈange in ｅneｒgｙ tｈat ｏcｃｕrs when a reaｃtion ｔake placｅ is ｄesｃribeｄ by thｅrｍｏdｙnamics(热力学)ａnd the rate or speed ａｔ ｗhich a reactiｏn ocｃｕrs is ｄeｓcribeｄ ｂｙ kinｅtics (动力学) ． Rｅactionｓ ｉn wｈiｃh the rｅaｃｔanｔs and products
coexist aｒe ｃoｎsidered ｔo be iｎ equilibｒium(处于平衡). Ａ cｈemical equation consiｓｔs of the chemiｃal fｏrmｕla（化学式）of the reaｃtaｎｔｓ, and tｈe cｈemicａl formula of tｈｅ prodｕcｔs。 Tｈｅ tｗo are ｓｅparated bｙ aｎ → ｕｓuａllｙ rｅad as “yieldｓ” anｄ ｅach cheｍical formｕlａ iｓ sepaｒated frｏｍ others ｂy a pｌus sign （加号) . Sｏmetimeｓ a trianｇｌe is drawn oveｒ the aｒrow symbol to denoｔe eｎｅrgｙ must be added to ｔhｅ suｂsｔanｃes for the rｅａction to ｂｅgｉｎ． Each cｈemiｃaｌ fｏｒmuｌa may ｂｅ precedeｄ by ａ scalａr （数量的） cｏｅfficｉｅｎt iｎdicaｔiｎg the proportioｎ （比例） of tｈａｔ substaｎｃｅ necessａｒy to prodｕcｅ the ｒeaｃtiｏn iｎ ｆｏrmｕla。 Fｏr ｉnstａnce, the ｆｏrｍula fｏr thｅ burｎｉng ｏｆ meｔｈane(ＣH4 + 2O2 → ＣＯ2 + ２H2O） ｉndｉcateｓ ｔｈat twiｃe as mｕch O2 ａs CH４ is needed, and when they rｅact, twｉce as much H2O as CＯ2 ｗill bｅ ｐｒoduceｄ。 Ｔhis ｉs becausｅ during ｔhe reactiｏｎ， ｅach atom ｏf carboｎ neeｄs exaｃtｌy two atoms of oxygen to coｍbiｎe with, to producｅ the CO2, ａnd ｅｖeｒｙ ｔｗo atoｍｓ of hydrogen nｅed aｎ atoｍ oｆ oｘygen to comｂinｅ witｈ to ｐr