📚 AQA A-Level Chemistry Required Practical Activities | AQA A-Level 化学必修实验活动
Required practical activities are an essential part of AQA A-Level Chemistry. They assess your ability to plan, carry out, analyse, and evaluate experiments. This guide summarises the 12 required practicals, linking key procedures, calculations, common errors, and safety points to exam-style questions.
必修实验活动是 AQA A-Level 化学的重要组成部分，考查你计划、实施、分析和评估实验的能力。本指南汇总 12 个必修实验，将关键操作、计算、常见误差和安全要点与考试题型联系起来。
1. Make Up a Volumetric Solution and Acid–Base Titration | 配制体积溶液与酸碱滴定
nvert several times to mix thoroughly. The concentration is calculated using c = n / V and n = m / M.
配制标准溶液时，用天平准确称量固体并记录质量，在烧杯中用少量蒸馏水溶解，然后将溶液及所有洗涤液转移到 250 cm³ 容量瓶中。用蒸馏水定容至刻度线，塞紧瓶塞并倒转数次充分混合。浓度用 c = n / V 计算，而 n = m / M。
In acid–base titration, rinse the burette with the acid and the pipette with the alkali, use a pipette filler, add a suitable indicator such as methyl orange or phenolphthalein, and run a rough titre followed by accurate titres until two concordant results agree within 0.10 cm³. Avoid parallax by reading the bottom of the meniscus at eye level.
酸碱滴定时，先用酸润洗滴定管，用碱润洗移液管，使用洗耳球，加入合适指示剂如甲基橙或酚酞，先进行一次粗滴定，再准确滴定直到两次一致结果相差在 0.10 cm³ 以内。读数时视线与弯月面底部平齐以避免视差。
2. Measurement of an Enthalpy Change | 测量焓变
and extrapolate to the mixing time to correct for cooling. The heat change is q = mcΔT, and the enthalpy change is ΔH = −q / n.
简单量热实验测量已知质量溶液反应时的温度变化。记录初始温度，加入第二种反应物，持续搅拌并记录最高或最低温度。如果温度变化缓慢，绘制温度-时间图并外推至混合时刻以校正冷却。热量变化为 q = mcΔT，焓变为 ΔH = −q / n。
Assume the solution has the density and specific heat capacity of water, 1.00 g cm⁻³ and 4.18 J g⁻¹ K⁻¹. Main errors are heat loss to the surroundings, incomplete reaction, and ignoring the heat capacity of the apparatus; insulation and a lid reduce heat loss.
假设溶液的密度和比热容与水相同，即 1.00 g cm⁻³ 和 4.18 J g⁻¹ K⁻¹。主要误差包括向环境散热、反应不完全以及忽略仪器的热容；使用隔热材料和盖子可以减少热损失。
3. Investigation of How Rate Changes with Temperature | 研究速率随温度的变化
In the sodium thiosulfate and hydrochloric acid reaction, sulfur forms and makes the solution cloudy. Place the conical flask on a cross, mix fixed volumes of the two solutions at a known temperature, and time how long it takes for the cross to disappear. Repeat at different temperatures, keeping all concentrations and volumes constant.
在硫代硫酸钠与盐酸的反应中，生成硫使溶液变浑浊。将锥形瓶放在十字标记上，在已知温度下混合固定体积的两种溶液，记录十字消失所需的时间。在不同温度下重复实验，保持所有浓度和体积
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