1.2.2 Neutralisation Reactions: Calculation Questions | 1.2.2 中和反应：计算题型

📚 1.2.2 Neutralisation Reactions: Calculation Questions | 1.2.2 中和反应：计算题型

Neutralisation calculations are a central part of A-Level Chemistry, bridging acid-base theory and quantitative analysis. This article covers typical problem types—from straightforward titrations to back titrations and pH curve interpretation—equipping you with the logical steps and formulas you need to tackle any exam question confidently.

中和反应计算是A-Level化学的核心内容，它连接酸碱理论与定量分析。本文涵盖从直接滴定到逆滴定、pH曲线解读等典型题型，帮助你掌握解题所需的逻辑步骤和公式，从容应对任何考试题目。

1. The Mole Ratio in Neutralisation | 中和反应中的摩尔比

All neutralisation calculations begin with the balanced chemical equation. The coefficients give the mole ratio of acid to base. For a monoprotic acid like HCl reacting with NaOH, the ratio is 1:1. For diprotic H₂SO₄, one mole of acid requires two moles of NaOH, so n(NaOH) = 2 × n(H₂SO₄).

所有中和计算都要从配平的化学方程式开始。化学计量数给出了酸与碱的摩尔比。对于一元酸 HCl 与 NaOH 的反应，比例为 1:1。对于二元酸 H₂SO₄，1 摩尔酸需要 2 摩尔 NaOH，因此 n(NaOH) = 2 × n(H₂SO₄)。

HCl + NaOH → NaCl + H₂O

H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O

H⁺ + OH⁻ → H₂O

Never skip writing the full equation—many mistakes stem from misreading the mole ratio. Even for familiar reactions, take a moment to confirm the coefficient linking the two reactants.

切勿跳过书写完整方程式这一步——许多错误都源于误判摩尔比。即使是熟悉的反应，也要花时间确认连接两种反应物的化学计量系数。

2. Standard Solutions and Titration Essentials | 标准溶液与滴定要点

A titration determines an unknown concentration by reacting it with a standard solution of precisely known concentration. Primary standards, such as anhydrous Na₂CO₃ or potassium hydrogen phthalate (KHP), must be pure, stable, and have a high molar mass to minimise weighing errors. The apparatus includes a burette, pipette, conical flask, and a suitable indicator.

滴定法通过与浓度精确已知的标准溶液反应，来测定未知溶液的浓度。基准物质（如无水 Na₂CO₃ 或邻苯二甲酸氢钾 KHP）必须纯净、稳定且摩尔质量较大，以减小称量误差。所用仪器包括滴定管、移液管、锥形瓶和合适的指示剂。

• Anhydrous Na₂CO₃: used to standardise strong acids like HCl or H₂SO₄.
• Potassium hydrogen phthalate (KHC₈H₄O₄): used to standardise strong bases like NaOH.

• 无水 Na₂CO₃：用于标定强酸，如 HCl 或 H₂SO₄。
• 邻苯二甲酸氢钾 (KHC₈H₄O₄)：用于标定强碱，如 NaOH。

Always rinse the burette with the solution it will contain and the pipette with the solution to be measured. An air bubble in the burette tip leads to a higher recorded volume, causing error.

滴定管要用待装溶液润洗，移液管要用待量取的溶液润洗。滴定管尖端有气泡会导致记录的体积偏大，引起误差。

3. Core Formula and Concentration Calculations | 核心公式与浓度计算

The foundational equation is n = c × V, where n is amount in mol, c is concentration in mol dm⁻³, and V is volume in dm³. Volumes measured in cm³ must be divided by 1000. For a 1:1 reaction, the titration formula simplifies to c₁V₁ = c₂V₂.

基本公式为 n = c × V，其中 n 为物质的量（mol），c 为浓度（mol dm⁻³），V 为体积（dm³）。以 cm³ 为单位测量的体积必须除以 1000。对于 1:1 的反应，滴定公式简化为 c₁V₁ = c₂V₂。

n = c × V

c(acid) × V(acid) = c(base) × V(base)

When the mole ratio is not 1:1, insert the coefficients. For

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