《酸碱理论》PPT课件

《《酸碱理论》PPT课件》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、酸碱解离平衡Acids&Bases4第四章第1节酸碱理论概述一Arrhenius酸碱理论二Bransted&lowrey酸碱质子理论三Lewis酸碱电子理论四酸碱溶剂体系理论定义酸：凡是在水中电离产生H+的物质。碱：凡是在水中电离产生OH+的物质。局限性：酸碱物质；酸碱反应；溶剂的影响。一Arrhenius酸碱理论二酸碱质子理论定义酸：凡是能给出质子的物质。碱：凡是能结合质子的物质。酸给出质子后变为碱；碱接受质子变为酸。WhenanHClmoleculedissolvesinwater,ahydrogenbondformsbe

2、tweentheHatomofHCl(theacid)andtheOatomofaneighboringH2Omolecule(thebase).ThenucleusofthehydrogenatomispulledoutoftheHClmoleculetobecomepartofahydroniumion.(1)Asubstancecanactasanacidonlyifabaseispresenttoacceptitsacidicprotons.(2)Anaciddoesnotsimplyreleaseitsacidicp

3、roton:theprotonistransferredtothebasethroughdirectcontact.Forexample,HClisaBrønstedacid.Inthegasphase,anHClmoleculeremainsintact.However,whenHCldissolvesinwater,eachHClmoleculeimmediatelytransfersanH+iontoaneighboringH2Omolecule,whichhereisactingasabase.Thisprocessi

4、saprotontransferreaction,areactioninwhichaprotonistransferredfromonespeciestoanother.WesaythattheHClmoleculebecomesdeprotonated:HCl(aq)+H2O(l)H3O+(aq)+Cl-(aq)Astrongacidisfullydeprotonatedinsolution.AweakacidisonlypartlydeprotonatedinsolutionWhenanoxideionispresenti

5、nwater,itexertssuchastrongattractiononthenucleusofahydrogenatominaneighboringwatermoleculethatthehydrogenionispulledoutofthemoleculeasaproton.Asaresult,theoxideionformstwohydroxideions.酸H++碱-++AcHHAc-+-+2442HPOHPOH-+-+3424POHHPO+++34NHHNH[]+++2333NHCHHNHCH++++252362

6、O)Fe(OH)(HHO)Fe(H[][]++++422252O)(HFe(OH)HO)Fe(OH)(H[][]共轭酸碱统一在同一体系中质子的传递上。共轭酸碱对Theconjugateacidofabaseistheacidthatformswhenthebasehasacceptedaproton.Astrongacidisfullydeprotonatedinsolution;aweakacidisonlypartiallydeprotonatedinsolution.Astrongbaseiscompletelyprot

7、onatedinsolution;aweakbaseisonlypartiallyprotonatedinsolution.酸和碱的强度是指酸给出质子的能力和碱接受质子的能力的强弱。酸越强，其共轭碱越弱；碱越强，其共轭酸越弱。三Lewis酸碱电子理论Lewis酸：凡是可以接受电子对的分子、离子或原子，如Fe3+,Fe,Ag+,BF3等；Lewis碱：凡是给出电子对的离子或分子，如:X－,:NH3,:CO,H2O:等。lewis酸与lewis碱之间以配位键结合生成酸碱加合物。Theblackcurvedarrowsshowthe

8、directioninwhichtheelectronscanbethoughttomove;theredcurvedarrowshowstheprotontransfer.ManynonmetaloxidesareLewisacidsthatreactwithwaterto