AS Chemistry Paper 1 Mark Scheme January 2018: Experimental Skills | AS 化学试卷1 评分方案 2018年1月：实验操作

📚 AS Chemistry Paper 1 Mark Scheme January 2018: Experimental Skills | AS 化学试卷1 评分方案 2018年1月：实验操作

Understanding the mark scheme for AS Chemistry Paper 1 is essential for mastering the experimental skills questions. The January 2018 paper included a variety of practical-based questions testing your knowledge of apparatus, techniques, safety, and data handling. This article breaks down key marking points from the official mark scheme, helping you avoid common mistakes and secure full marks in the experimental section.

理解 AS 化学试卷1的评分方案对于掌握实验操作题目至关重要。2018年1月的试卷包含了多种基于实验的问题，考察你对仪器、技术、安全和数据处理的了解。本文详细解析官方评分方案中的关键评分要点，帮助你避免常见错误，在实验部分获得满分。

1. Standard Laboratory Apparatus | 常用实验仪器

The mark scheme often awards marks for correctly identifying or naming laboratory apparatus. In the January 2018 exam, a question showed a diagram of a beaker, a conical flask, a measuring cylinder, and a burette. The correct answer was the burette for delivering a precise variable volume of liquid.

评分方案通常会对正确识别或命名实验仪器给予分数。在2018年1月的考试中，有一道题展示了烧杯、锥形瓶、量筒和滴定管的示意图。正确答案是滴定管，因为它可以精确地放出可变量液体。

Common marks were lost when students confused a pipette (fixed volume) with a burette (variable volume). The mark scheme explicitly states that a pipette delivers a single fixed volume, while a burette is used for titration.

当学生混淆移液管（固定体积）和滴定管（可变体积）时，通常会失分。评分方案明确指出，移液管用于移取单一固定体积，而滴定管用于滴定。

• Beaker – used for mixing and heating, not precise. 烧杯 – 用于混合和加热，不精确。
• Conical flask – used in titration, allows swirling. 锥形瓶 – 用于滴定，可摇动。
• Measuring cylinder – approximate volume measurement. 量筒 – 近似体积测量。
• Burette – delivers variable precise volumes. 滴定管 – 可精确放出可变体积。
• Pipette – delivers a fixed volume accurately. 移液管 – 精确移取固定体积。

---

2. Measuring Volumes Accurately | 精确测量体积

A recurring theme in the January 2018 mark scheme is the distinction between accuracy and precision. When measuring a liquid, the meniscus must be read at eye level. The mark scheme often deducts a mark if the student fails to mention reading the bottom of the meniscus for clear liquids.

2018年1月评分方案中的一个反复出现的主题是准确度与精密度的区别。在测量液体时，必须与液面水平读取弯月面。评分方案通常会在学生未提及读取透明液体弯月面底部时扣分。

The mark scheme also highlights that a volumetric pipette is rinsed with the solution to be transferred, while a burette is rinsed with the titrant. Rinsing with water only would introduce errors.

评分方案还强调，移液管需用待移取溶液润洗，而滴定管需用滴定剂润洗。仅用水润洗会引入误差。

A common question: ‘Why is a pipette filler used?’ Answer: safety, avoids mouth pipetting. Marks were given for safety reason.

常见问题：“为什么要使用吸耳球？”答案：安全，避免用嘴吸取。给出安全原因能得分。

---

3. Burette, Pipette and Volumetric Flask | 滴定管、移液管与容量瓶

The January 2018 Paper 1 included a question requiring students to choose the correct apparatus for preparing a standard solution. The mark scheme confirms: use a volumetric flask (e.g. 250 cm³) and dissolve the solid in a beaker first, then transfer with washings.

2018年1月试卷1中有一道题要求学生选择配制标准溶液的正确仪器。评分方案确认：使用容量瓶（如250 cm³），先将固体溶解在烧杯中，然后转移并洗涤。

Key point: the volumetric flask must be inverted several times to ensure homogeneity. Marks were awarded for mentioning mixing.

关键点：容量瓶必须反复倒转数次以确保均匀。提及混合能得分。

Burette readings should be recorded to the nearest 0.05 cm³, because the graduations are every 0.1 cm³. The mark scheme accepts readings ending in .00, .05, .10, etc.

滴定管读数应记录到最接近0.05 cm³，因为刻度每格0.1 cm³。评分方案接受读数末位为 .00, .05, .10 等。

---

4. Titration Technique and Common Errors | 滴定技术与常见错误

In the titration questions of January 2018, common errors included not removing the funnel after filling the burette, causing a drop of solution to fall and affect the initial reading. The mark scheme penalised this oversight.

在2018年1月的滴定问题中，常见错误包括在装满滴定管后未移走漏斗，导致一滴溶液落下影响初始读数。评分方案对这一疏忽扣分。

Air bubbles in the jet of the burette must be removed before titration. Insufficient swirling of the conical flask may lead to an endpoint overshoot. The mark scheme expected students to identify these sources of error.

滴定管尖嘴处的气泡必须在滴定前排除。锥形瓶摇动不充分可能导致终点过头。评分方案期望学生能识别这些误差来源。

The use of a white tile under the flask improves detection of the colour change. Marks were given for improving accuracy of endpoint judgment.

在烧瓶下放置白色瓷砖可改善颜色变化的察觉。提高终点判断的准确性可得分。

---

5. Flame Tests and Identification | 焰色试验与离子鉴别

In the January 2018 paper, a question tested identification of cations using flame tests. The mark scheme required knowledge of the colours: lithium (red), sodium (yellow), potassium (lilac), calcium (brick red), barium (green), copper (blue-green).

在2018年1月的试卷中，有一道题考察使用焰色试验鉴别阳离子。评分方案要求掌握颜色：锂（红）、钠（黄）、钾（淡紫）、钙（砖红）、钡（绿）、铜（蓝绿）。

Common mistake: confusing potassium (lilac) with calcium (brick red). The mark scheme mentioned that viewing through blue glass helps distinguish potassium in the presence of sodium.

常见错误：将钾（淡紫）与钙（砖红）混淆。评分方案提到，通过蓝色钴玻璃观察有助于在钠存在下区分钾。

Nichrome wire must be cleaned with concentrated HCl and heated until no colour imparted. Marks are often assigned for explaining cleaning procedures.

镍铬丝必须用浓盐酸清洗并加热至没有颜色。解释清洗程序常被分配分数。

---

6. Separation Techniques: Filtration and Evaporation | 分离技术：过滤与蒸发

Filtration questions appeared in the January 2018 mark scheme, focusing on the correct setup (filter paper, funnel, beaker) and the role of the residue and filtrate. The scheme stressed that filtration separates an insoluble solid from a liquid.

2018年1月的评分方案中出现了过滤问题，重点在正确装置（滤纸、漏斗、烧杯）以及残渣和滤液的作用。方案强调过滤用于分离不溶性固体与液体。

Evaporation to dryness is used to obtain a soluble salt from a solution, but care must be taken to avoid overheating and decomposition. The mark scheme penalised mention of heating to dryness without caution.

蒸发至干用于从溶液中获得可溶性盐，但必须注意避免过热和分解。评分方案对未加留意地提到加热至干会扣分。

Crystallisation (heating until saturation, then cooling) is preferred for obtaining hydrated crystals. Marks were given for describing the steps.

结晶（加热至饱和，然后冷却）更适合获得含水晶体。描述步骤能得分。

---

7. Distillation and Reflux | 蒸馏与回流

A question in January 2018 required distinguishing simple distillation from fractional distillation. The mark scheme expected students to identify that simple distillation is for separating a solvent from a non-volatile solute, while fractional distillation separates miscible liquids with different boiling points.

2018年

Published by TutorHao | Chemistry Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）