📚 Acids and Bases | 酸与碱
Acids and bases are cornerstones of chemistry, governing processes from enzyme activity to industrial synthesis. A robust understanding requires mastery of proton-transfer models, quantitative pH relationships, equilibria, and practical techniques such as titrations and buffer preparation. This revision guide presents the essential concepts of acid–base chemistry tailored to the IB programme, interweaving theory, calculations, and real-world relevance.
酸和碱是化学的基石，主导着从酶活性到工业合成的各种过程。深入理解它们需要掌握质子转移模型、定量的pH关系、平衡以及滴定和缓冲液制备等实用技术。本复习指南专为IB课程量身打造，交织了理论、计算和现实意义。
1. Introduction and Key Definitions | 引言与关键定义
The IB Chemistry syllabus focuses on the Brønsted–Lowry and Lewis definitions of acids and bases. Although Arrhenius's idea of H⁺ and OH⁻ producers is historically important, it fails to explain acid–base behaviour in non-aqueous solvents or gas-phase reactions. Modern frameworks allow us to analyse a much wider range of chemical systems.
IB化学教学大纲重点考查布朗斯特-劳里和路易斯酸碱定义。尽管阿伦尼乌斯提出酸产生H⁺、碱产生OH⁻的观点具有历史意义，但它无法解释非水溶剂或气相中的酸碱行为。现代框架使我们能够分析更广泛的化学体系。
Students are expected to identify conjugate acid–base pairs, perform pH calculations for strong and weak species, interpret titration curves, understand buffer action, and select suitable indicators. A firm grasp of equilibrium principles, including the acid dissociation constant Ka and the ionic product of water Kw, is essential.
学生需要能够识别共轭酸碱对、计算强酸强碱和弱酸弱碱的pH、解读滴定曲线、理解缓冲作用机理，并选择合适的指示剂。扎实掌握平衡原理，包括酸解离常数Ka和水的离子积Kw，是必不可少的。
2. Brønsted–Lowry Theory | 布朗斯特-劳里酸碱理论
A Brønsted–Lowry acid is a proton (H⁺) donor, and a base is a proton acceptor. In an acid– this: HCl is the acid, H₂O the base, H₃O⁺ the conjugate acid, and Cl⁻ the conjugate base.
布朗斯特-劳里酸是质子（H⁺）的供体，碱是质子的受体。在酸碱反应中，酸向碱转移一个质子。给出质子后，酸变成其共轭碱；接受质子后，碱变成其共轭酸。反应HCl + H₂O → H₃O⁺ + Cl⁻说明了这一点：HCl是酸，H₂O是碱，H₃O⁺是共轭酸，Cl⁻是共轭碱。
). The hydrogen carbonate ion HCO₃⁻ is another example, capable of forming CO₃²⁻ or H₂CO₃.
有些物质既能提供质子也能接受质子，称为两性物质。水就是两性的：遇到更强的酸时它作为碱（H₂O + H⁺ → H₃O⁺），遇到更强的碱时它作为酸（H₂O → OH⁻ + H⁺）。碳酸氢根离子HCO₃⁻是另一个例子，它能形成CO₃²⁻或H₂CO₃。
A strong acid has a weak conjugate base, and a weak acid has a relatively strong conjugate base. This inverse relationship helps predict the direction of proton transfer equilibria.
强酸的共轭碱为弱碱，弱酸的共轭碱相对较强。这种反向关系有助于预测质子转移平衡的方向。
3. Lewis Theory of Acids and Bases | 路易斯酸碱理论
The Lewis definition broadens the concept: a Lewis acid is an electron-pair acceptor, and a Lewis base is an electron-pair donor. This framework includes species that do not exchange protons. For example, BF₃ accepts an electron pair from NH₃, forming a coordinate covalent bond. BF₃ is the Lewis acid, NH₃ is the Lewis base.
路易斯定义拓宽了概念：路易斯酸是电子对受体，路易斯碱是电子对供体。此框架涵盖不交换质子的物种。例如，BF₃接受来自NH₃的一对电子，形成配位共价键。BF₃是路易斯酸，NH₃是路易斯碱。
Many metal cations act as Lewis acids. Cu²⁺ and Fe³⁺ accept electron pairs from water or ammonia molecules to form complex ions such as [Cu(H₂O)₆]²⁺. This behaviour is central to transition-metal chemistry and explains the acidity of some metal salt solutions.
许多金属阳离子充当路易斯酸。Cu²⁺和Fe³⁺从水或氨分子接受电子对，形成如[Cu(H₂O)₆]²⁺的配合物离子。这一行为是过渡金属化学的核心，也解释了一些金属盐溶液的酸性。
The Lewis model
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