Experimental Techniques for Oxford AQA CH02 – June 2023 Mark Scheme Insights | Oxford AQA CH02 实验操作指南——基于2023年6月评分方案深度解析

📚 Experimental Techniques for Oxford AQA CH02 – June 2023 Mark Scheme Insights | Oxford AQA CH02 实验操作指南——基于2023年6月评分方案深度解析

The Oxford AQA CH02 paper frequently tests candidates on practical procedures and the ability to interpret experimental results. By studying the June 2023 mark scheme, students can uncover exactly what examiners expect in answers related to experimental techniques—from precise burette readings to correct reflux setup. This article breaks down essential laboratory operations, highlighting key marking points to help you secure full marks on practical-based questions.

牛津AQA CH02考试经常考查实验操作步骤及对实验结果的解读能力。通过分析2023年6月评分方案，学生能够准确了解考官在实验技术相关题目中的评分要求——从精准的滴定管读数到正确的回流装置。本文将详细剖析核心实验操作，重点说明评分要点，助你在实验题中拿到满分。

1. Titration Setup and Burette Reading | 滴定装置与滴定管读数

A burette must be rinsed first with deionised water and then with the titrant solution to ensure the concentration is not altered by residual water.

滴定管需先用去离子水润洗，再用待装滴定液润洗，以确保残留水分不会改变溶液浓度。

The burette tap should be opened to fill the tip completely, and any air bubbles must be removed before starting the titration.

应打开滴定管活塞，使溶液充满滴定管尖嘴，并在开始滴定前排除管尖的气泡。

According to the June 2023 mark scheme, candidates must record initial and final burette readings to the nearest 0.05 cm³, and the titre volume is the difference between these two readings.

根据2023年6月评分方案，考生必须记录滴定管初读数和末读数，精确至0.05 cm³，滴定体积即为两次读数之差。

The correct indicator for a strong acid–strong base titration is phenolphthalein or methyl orange, but the colour change must be described accurately (e.g., colourless to pink).

强酸强碱滴定可选用酚酞或甲基橙作指示剂，但务必准确描述颜色变化（如由无色变为粉红色）。

2. Preparing a Standard Solution | 配制标准溶液

A solid primary standard such as potassium hydrogenphthalate (KHC₈H₄O₄) must be weighed accurately on a balance recording to two decimal places.

固体基准物如邻苯二甲酸氢钾 (KHC₈H₄O₄) 需用精确到小数点后两位的天平准确称量。

After dissolving the solid in a beaker with deionised water, the solution is transferred quantitatively into a 250 cm³ volumetric flask using a funnel, and the beaker should be rinsed several times with deionised water, adding the washings to the flask.

在烧杯中用去离子水溶解固体后，使用漏斗将溶液定量转移至250 cm³容量瓶中，烧杯需用去离子水清洗多次，并将洗涤液一并转移至容量瓶。

Once the solution is near the calibration mark, a dropping pipette is used to add water dropwise until the bottom of the meniscus is exactly on the mark.

当溶液液面接近刻度线时，用滴管逐滴加水，直至弯月面最低点刚好与刻度线相切。

The flask is then stoppered and inverted several times to ensure thorough mixing, which prevents concentration gradients.

随后塞紧瓶塞，将容量瓶反复倒转数次，确保溶液均匀混合，避免产生浓度梯度。

Mark schemes often penalise forgetting to invert the flask or failing to rinse the beaker and funnel.

评分方案常常扣分点在于忘记倒转容量瓶混匀或未冲洗烧杯和漏斗。

3. Heating under Reflux for Organic Synthesis | 有机合成中的回流加热

Reflux is used to allow a reaction mixture to be heated at its boiling point for an extended period without loss of volatile components.

回流加热用于使反应混合物在沸点下长时间加热，同时防止挥发性组分损失。

The apparatus consists of a round-bottom flask attached to a vertical condenser. Water enters the condenser at the lower inlet and exits from the upper outlet to ensure efficient cooling.

装置由圆底烧瓶和竖直放置的冷凝管组成。冷却水从冷凝管下口进入、上口排出，以确保充分冷却。

Anti-bumping granules (boiling chips) must be added to the flask before heating to promote smooth boiling and prevent violent bumping.

加热前必须向烧瓶中加入防沸石（沸石），以促进

Published by TutorHao | Chemistry Revision Series | aleveler.com

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