149-6-0酸碱基本理论概述

1、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。When an HCl molecule dissolves in water, a hydrogen bond forms between the H atom of HCl (t

2、he acid) and the O atom of a n e i g h b o r i n g H 2 O molecule (the base). The nucleus of the hydrogen atom is pulled out of the HCl molecule to become part of a hydronium ion.(1) A substance can act as an acid only if a base is present to accept its acidic protons.(2) An acid does not simply rel

3、ease its acidic proton: the proton is transferred to the base through direct contact. For example, HCl is a Brnsted acid. In the gas phase, an HCl molecule remains intact. However, when HCl dissolves in water, each HCl molecule immediately transfers an H+ ion to a neighboring H2O molecule, which her

4、e is acting as a base. This process is a proton transfer reaction, a reaction in which a proton is transferred from one species to another. We say that the HCl molecule becomes deprotonated: HCl(aq) + H2O(l) H3O+(aq) + Cl-(aq)A strong acid is fully deprotonated in solution.A weak acid is only partly

5、 deprotonated in solutionWhen an oxide ion is present in water, it exerts such a strong attraction on the nucleus of a hydrogen atom in a neighboring water molecule that the hydrogen ion is pulled out of the molecule as a proton. As a result, the oxide ion forms two hydroxide ions.酸 H+ +碱-+AcHHAc -+

6、-+2442HPOHPOH-+-+3424POHHPO+34NHHNH+2333NHCHHNHCH +252362O)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The conjugate acid of a base is the acid that forms when the base has accepted a proton. A strong acid is fully deprotonated in solution; a weak acid is only partially deprot

7、onated in solution. A strong base is completely protonated in solution; a weak base is only partially protonated in solution. 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。OHNHCOHHAc POHSOHHClO 243243424酸性：OHNHHCOAc POH HSO ClO 334244碱性： 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+,

8、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。The black curved arrows show the direction in which the electrons can be thought to move; the red curved arrow shows the proton transfer.Many nonmetal oxides are Lewis acids that react with water to give Brnsted acids.The C atom of CO2, the Lewis acid, accepts an electron pair from the O atom of a water molecule, the Lewis base, and a proton migrates from an H2O oxygen atom to a CO2 oxygen atom.ClHHNH H NH HCl3 FFBF F BF3 + F23333NH NH CuNH NH Cu2+ + 4 NH3