📚 Required Practical Activities: Exemplar Experiments for AQA A-Level Chemistry | AQA A-Level 化学必修实验活动：范例实验
The AQA A-level Chemistry specification includes twelve required practical activities. These exemplar experiments develop essential skills such as making standard solutions, measuring temperature and pH changes, controlling organic reactions, and using qualitative and quantitative analysis. This article summarises the core method, key data and common errors for each activity.
AQA A-level 化学大纲包含 12 个必修实验活动。这些范例实验培养关键技能，包括配制标准溶液、测量温度和 pH 变化、控制有机反应以及进行定性和定量分析。本文概述每个活动的核心方法、关键数据和常见误差。
1. Making a Volumetric Solution and Acid-Base Titration | 配制容量溶液与酸碱滴定
hyl orange as indicator; concordant titres should agree within 0.10 cm³. Since Na₂CO₃ + 2HCl → 2NaCl + CO₂ + H₂O, the mean titre allows the concentration of the acid to be calculated.
标准溶液的配制方法是准确称取约 2.65 g 无水 Na₂CO₃，用去离子水溶解后转移至 250.0 cm³ 容量瓶中，定容并充分摇匀。用该溶液在滴定管下滴定盐酸，以甲基橙为指示剂；协同滴定值应相差不超过 0.10 cm³。由于 Na₂CO₃ + 2HCl → 2NaCl + CO₂ + H₂O，通过平均滴定值可以计算盐酸浓度。
The burette must be rinsed with the acid solution it will contain, and the pipette with the sodium carbonate solution it will deliver. A white tile placed under the flask makes the methyl orange colour change from yellow to red easier to see. The bottom of the meniscus must be read at eye level to avoid parallax error.
滴定管必须用待装酸液润洗，移液管用待移取的碳酸钠溶液润洗。锥形瓶下垫白色瓷砖，有助于观察甲基橙由黄变红的终点。读数时视线应与弯月面底部齐平，以避免视差。
2. Measurement of an Enthalpy Change | 测量焓变
m is the mass of solution. The enthalpy change per mole of limiting reactant is ΔH = -q/n.
在聚苯乙烯杯量热计中，记录已知体积 CuSO₄ 溶液的初始温度；加入过量锌粉并搅拌。记录最高温度以求得 ΔT。热量变化为 q = mcΔT，其中 c = 4.18 J g⁻¹ K⁻¹，m 为溶液质量。每摩尔限制反应物的焓变为 ΔH = -q/n。
Main errors are heat loss to the surroundings and the assumption that the solution has the same density and specific heat capacity as water. Using a lid and stirring continuously improve accuracy. The temperature rise should be measured to the nearest 0.5 °C or better.
主要误差是热量向环境散失，以及假设溶液密度和比热容与水相同。加盖并持续搅拌可提高准确性。温度升高应读取至 0.5 °C 或更精确。
3. Investigation of How Reaction Rate Changes with Temperature | 探究反应速率随温度变化
of 1/t against temperature, or ln(1/t) against 1/T, shows that rate increases with temperature, supporting the Arrhenius model.
消失十字实验将硫代硫酸钠溶液与稀盐酸在不同温度下混合，记录硫沉淀遮住瓶底十字所需的时间。反应方程式为 S₂O₃²⁻ + 2H⁺ → S + SO₂ + H₂O。以 1/t 对温度作图，或以 ln(1/t) 对 1/T 作图，表明速率随温度升高而增大，支持阿伦尼乌斯模型。
Only the temperature of the thiosulfate solution is changed; the acid concentration, total volume and viewing angle must be controlled. Each solution must be brought to the required temperature in a water bath before mixing, and the flask should be dry and clean so the cross can be seen clearly at the start.
只改变硫代硫酸钠溶液的温度；酸的浓度、总体积和观察角度必须控制。每种溶液在混合前应在水浴中达到所需温度，烧瓶应干燥洁净，使开始时能清晰看到十字。
4. Test
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