CIE 化学
CIE Chemistry 9701 P3 Concept Map (Advanced Practical)
28 个知识节点 · P3
1. Method literacy
Read method first & tables（通读步骤与表格）
📖 DefinitionPaper 3 通用指令：先通读整段方法；在空白处自行设计表格；记录须体现仪器精度。
🔑 KeyQuantitative analysis 段首三句：Read through the whole method…；prepare a table…；Show the precision…
🎯 Exam focusQuestion 1 与 Question 2 常可穿插（如等待 15 min 时开始做 Q2）。
🛠️ Technique表头格式：quantity / unit，与 MS headings 判分一致。
CIE 9701/33/O/N/24 (Quantitative Analysis header)
Read through the whole method before starting any practical work. Where appropriate, prepare a table for your results in the space provided. Show the precision of the apparatus you used in the data you record. Show your working and appropriate significant figures in the answer to each step of your calculations.
先执行整段方法；表格含表头与单位；原始数据位数与量筒/天平分度一致；计算逐步写 working。
[M] 与 9701_w24_qp_33 卷首指令及 MS 9701_w24_ms_33 对 precision 的判分一致。
CIE 9701/31/O/N/24 (Quantitative analysis header)
Read through the whole method before starting any practical work. Where appropriate, prepare a table for your results in the space provided. Show the precision of the apparatus you used in the data you record. Show your working and appropriate significant figures in the answer to each step of your calculations.
同左：适用于热滴定 9701/31 整卷定量部分。
[M] 9701_w24_qp_31 卷首。
Headings, units & precision（表头与精度）
📖 Definition滴定表须含 initial / final burette readings、titre；单位 \mathrm{cm^3}。天平读数全卷 2 d.p. 或 3 d.p. 一致。
🔑 KeyBurette：所有准确读数至 nearest 0.05\ \mathrm{cm^3}（MS 9701/33 Q2(a) III）。
🎯 Exam focus单位写在表头或每个数值旁均可（MS 接受）。
🛠️ Technique列完表后自查：是否每一列都有 name + / unit。
CIE 9701/33/O/N/24 Q2(a) instructions
Make sure any recorded results show the precision of your practical work. Record all your burette readings and the volume of FA 4 added in each accurate titration.
滴定管读数估读至 0.05 cm³；表头含 initial/start、final/end、titre 及单位。
[M] MS 9701_w24_ms_33 2(a) II–III。
CIE 9701/33/O/N/24 Q1(a) (balance data)
Weigh the conical flask containing FA 2. Record the mass. Weigh the container with FA 1. Record the mass. … Calculate the mass of FA 1 added. Record the mass.
四次关键称量同一小数位；差减法求 m(\mathrm{FA\,1}) 须正确。
[M] MS 9701_w24_ms_33 1(a) II。
2. Balance & CO₂ mass loss
Mass loss \(x+y-z\)（质量差）
📖 DefinitionMS 用 x、y、z 表示 flask+酸、加入碳酸盐质量、反应后总质量；m(\mathrm{CO_2})=x+y-z。
🔑 KeyIonic equation：\mathrm{CO_3^{2-}(aq)}+2\mathrm{H^+(aq)}\rightarrow \mathrm{CO_2(g)}+\mathrm{H_2O(l)}。
🎯 Exam focus勿漏称“空容器 + 残余固体”。
🛠️ Technique在表中标注 MS 所称的 x, y, z 与卷面一致，便于阅卷对照 1(b)(i)。
CIE 9701/33/O/N/24 Q1(b)(i)
(i) Use your readings to calculate the mass of carbon dioxide produced. mass of CO2 = .............................. g
m(\mathrm{CO_2})=x+y-z（与 1(a) 各质量定义一致），2–4 s.f.。
[M] MS 9701_w24_ms_33 1(b)(i)：Mass loss = x + y – z; answer 2–4 sig figs.
CIE 9701/31/O/N/24 Q2(a) (mass of CO₂)
Calculate and record the mass of carbon dioxide given off during the experiment.
与 9701/31 质量表配套：用 flask + acid + sample 初末质量差求 \mathrm{CO_2}。
[M] MS 9701_w24_ms_31 Q2(a) IV：Correctly calculates mass CO₂ (1 + 2 – 3 – 4).
\(M_r\) from \(\mathrm{CO_2}\)（相对式量）
📖 Definitionn(\mathrm{CO_2})=m/44；M_r=m(\mathrm{FA\,1})/n(\mathrm{CO_2})。
🔑 KeyMS M1 + M2 分步；答案 2–4 s.f.。
🎯 Exam focus固体质量用实际加入量 y。
🛠️ Technique先写 n 再写 M_r；单位 mol、g 标清。
CIE 9701/33/O/N/24 Q1(b)(ii)
(ii) The ionic equation for the reaction of FA 1 with FA 2 is shown. CO₃²⁻(aq) + 2H⁺(aq) → CO₂(g) + H₂O(l). Calculate the relative formula mass, Mr, of the metal carbonate FA 1. Show your working. Mr of FA 1 = .............................. [2]
M1 n(\mathrm{CO_2})=(\mathrm{b})(\mathrm{i})/44；M2 M_r=m(\mathrm{FA\,1})\times44/(\mathrm{b})(\mathrm{i})。
[M] MS 9701_w24_ms_33 1(b)(ii).
CIE 9701/33/O/N/24 Q2(c)(ii)–(iv)
(ii) Calculate the amount, in mol, of hydrochloric acid present in the volume of FA 4 calculated in (b). (iii) Calculate the concentration, in mol dm⁻³, of metal carbonate in FA 3. (iv) Calculate the relative formula mass, Mr, of the metal carbonate in FA 1.
链式计算；(c)(i) 要求 (c)(ii)–(iv) 均为 3 或 4 位有效数字。
[M] MS 9701_w24_ms_33 2(c)(i) envelope + 各步 M。
3. Systematic error & apparatus
Colder acid & \(M_r\) bias（冷酸系统误差）
📖 Definition低温下 \mathrm{CO_2} 溶解度升高或反应变慢 \rightarrow 测得逸出 \mathrm{CO_2} 偏少 \rightarrow 算得 M_r 偏高。
🔑 KeyMS 要求 M1 现象 + M2 与 moles / M_r 方向挂钩。
🎯 Exam focus必须对比 **your** M_r 与 **student** M_r（higher / lower）。
🛠️ Technique用 “less CO₂ escaped / mass loss reduced → higher Mr” 模板。
CIE 9701/33/O/N/24 Q1(c)(i)
(c) (i) A student carries out the experiment as described in (a), except that the acid used is 15 °C colder than the acid you used. The student calculates the Mr correctly from the readings obtained. State whether the value of the Mr calculated by the student is higher or lower than the value you calculated in (b)(ii). Explain your answer. [2]
Higher Mr：更多 \mathrm{CO_2} 溶于溶液 / 逸出少 \rightarrow n(\mathrm{CO_2}) 偏小；或反应慢导致质量损失偏小。
[M] MS 9701_w24_ms_33 1(c)(i) M1+M2。
CIE 9701/33/O/N/24 Q1 intro
When a metal carbonate reacts with a suitable acid, carbon dioxide is produced. You will determine the relative formula mass, Mr, of a metal carbonate by reacting it with excess hydrochloric acid and measuring the mass of gas produced. FA 1 is the metal carbonate. FA 2 is 2.00 mol dm⁻³ hydrochloric acid, HCl.
(c)(i) 中 “colder acid” 仍属同一实验框架：逸出 \mathrm{CO_2} 量影响 M_r 推断。
[M] QP 9701_w24_qp_33 Q1 开篇（实验目的与试剂）。
Tilting conical flask（倾斜锥形瓶）
📖 Definition几乎水平有利于空气置换 \mathrm{CO_2} 或酸接触器壁固体。
🔑 KeyMS 1(c)(ii) 1 mark：air replaces CO₂ / tips out denser CO₂ / acid reaches solid on walls (owtte)。
🎯 Exam focusExplain why the student is **correct**（题干用词）。
🛠️ Technique一句机制即可，勿与 (c)(i) 因果矛盾。
CIE 9701/33/O/N/24 Q1(c)(ii)
(ii) Another student suggests that the experiment will be more accurate if the conical flask is tilted carefully to an almost horizontal position while the reaction is taking place. Explain why the student is correct. [1]
Allows air to replace / displace CO₂ in the flask; or tips out denser CO₂ gas; or allows acid to react with solid on walls。
[M] MS 9701_w24_ms_33 1(c)(ii).
CIE 9701/33/O/N/24 Q1(a) method
Tip all the FA 1 slowly into the conical flask. When the reaction slows, swirl the flask gently.
与倾斜互补：促进混合与气体离开液面（实验操作素养）。
[M] 9701_w24_qp_31/33 方法原文。
4. Uncertainty
Balance uncertainty \(U\)（单次读数不确定度）
📖 Definition2 d.p. 天平：MS 允许 U=0.01\ \mathrm{g} 或 U=0.005\ \mathrm{g}。
🔑 Key与 “single balance reading” 题干对应。
🎯 Exam focus勿把差量的不确定度当成单次读数。
🛠️ Technique先写 U，再写百分误差式。
CIE 9701/33/O/N/24 Q1(d)
(d) State the uncertainty in a single balance reading. uncertainty = ± .............................. g
0.01\ \mathrm{g} 或 0.005\ \mathrm{g}（与 2 d.p. 一致）。
[M] MS 9701_w24_ms_33 1(d).
CIE 9701/33/O/N/24 Q1(d)
Give an expression that would enable you to calculate the percentage error in your weighing of FA 1.
\%\text{error} = 2\times U / m(\mathrm{FA\,1})\times 100（两次读数得质量）。
[M] MS 9701_w24_ms_33 1(d)：% error = 2 × U / mass of FA1 × 100.
% error in weighing FA 1（百分误差应用）
📖 Definition分母为用于计算的 m(\mathrm{FA\,1})；分子为 2U（两次称量各贡献一次不确定度）。
🔑 Key与 1(d) 同一 MS 行。
🎯 Exam focus若 U 错但表达式对，可能仍有部分 ecf（见 MS 总则）。
🛠️ Technique百分数结果保留合理位数。
CIE 9701/33/O/N/24 Q1(d) (full part)
State the uncertainty in a single balance reading. Give an expression that would enable you to calculate the percentage error in your weighing of FA 1. [1]
U=0.01\ \mathrm{g} 或 0.005\ \mathrm{g}；\%\text{error} = 2\times U / m(\mathrm{FA\,1})\times 100。
[M] MS 9701_w24_ms_33 1(d)。
CIE 9701/33/O/N/24 Q1(b)(i)
(i) Use your readings to calculate the mass of carbon dioxide produced. mass of CO2 = .............................. g
与 1(d) 同属定量链：m(\mathrm{CO_2})=x+y-z；百分误差分母常用 m(\mathrm{FA\,1}) 而非 m(\mathrm{CO_2})。
[M] MS 9701_w24_ms_33 1(b)(i)（对比数据选用）。
5. Burette recording
Burette headings & 0.05 cm³
📖 DefinitionRough titre + 至少两次 accurate titrations；读数 0.05\ \mathrm{cm^3}。
🔑 KeyMS 9701/33 Q2(a) I–IV 为高频采分点。
🎯 Exam focusConcordant titres：\le 0.10\ \mathrm{cm^3} spread。
🛠️ Technique粗滴定单独占格；准确滴定另表。
CIE 9701/33/O/N/24 Q2(a) bullets
Fill the burette with FA 4. Pipette 25.0 cm³ of FA 3 into a conical flask. Add a few drops of FA 5 into the same conical flask. Perform a rough titration and record your burette readings in the space below. … Record all your burette readings and the volume of FA 4 added in each accurate titration. [7]
对应 MS：rough 两读数+titre；准确表头+单位；准确读数 0.05 cm³； titre 差 ≤0.10 cm³。
[M] MS 9701_w24_ms_33 2(a) I–IV。
CIE 9701/34/O/N/24 Q1(a) method
Run FB 2 into the conical flask until the colour of the solution turns yellow. Then add 10 drops of FB 3. The solution will turn blue-black. The end-point of the titration is when the solution turns colourless.
黄后加淀粉；终点 colourless；与 I₂ / S₂O₃²⁻ 计量一致。
[M] 9701_w24_qp_34。
Concordancy & Q marks
📖 Definition与 supervisor mean titre 比较，按 \delta 阈值给 V–VII 分档； titre 区间不同阈值不同。
🔑 KeyDefault：\delta\le 0.50、0.30、0.20\ \mathrm{cm^3}； titre \gt 50 或 \lt 10、\lt 5\ \mathrm{cm^3} 时换表。
🎯 Exam focus9701/33 Q1(a) III 为 balance accuracy：\pm 15\% on mass of FA 1 or mass loss。
🛠️ Technique先在卷面圈 supervisor 值再比 candidate。
CIE 9701/33/O/N/24 Q2(a) (titration instructions)
Fill the burette with FA 4. Pipette 25.0 cm³ of FA 3 into a conical flask. Add a few drops of FA 5 into the same conical flask. Perform a rough titration and record your burette readings in the space below. The rough titre is .............................. cm³. Carry out as many accurate titrations as you think necessary to obtain consistent results. Make sure any recorded results show the precision of your practical work. Record all your burette readings and the volume of FA 4 added in each accurate titration. [7]
Concordant titres 与 supervisor mean 的 \delta 对照见 MS 2(a) V–VII（阈值 0.20 / 0.30 / 0.50 cm³ 等）。
[M] QP 9701_w24_qp_33 + MS 9701_w24_ms_33 2(a) V–VII。
CIE 9701/33/O/N/24 Q1(a) (weighing method)
Use the measuring cylinder to transfer 30.0 cm³ of FA 2 into a conical flask. Weigh the conical flask containing FA 2. Record the mass. Weigh the container with FA 1. Record the mass. Tip all the FA 1 slowly into the conical flask. When the reaction slows, swirl the flask gently. Weigh the container with any residual FA 1. Record the mass. Calculate the mass of FA 1 added. Record the mass. Leave the conical flask and its contents for 15 minutes. Swirl the flask occasionally during this time. During this period begin work on Question 2. After 15 minutes weigh the flask and its contents. Record the mass. [3]
Q 档（III）由 MS 将 candidate 的 mass of FA 1 或 mass loss 与 supervisor 比较（±15%）；题干为上述称量步骤。
[M] QP 9701_w24_qp_33 Q1(a) + MS 9701_w24_ms_33 1(a) III。
6. Mean titre & s.f.
Mean titre rules
📖 Definition仅平均 spread \le 0.20\ \mathrm{cm^3} 的 accurate titres；mean 2 d.p.。
🔑 KeyMS 示例：26.675 → 26.68 cm³。
🎯 Exam focus须 show clearly how obtained / ticks。
🛠️ Technique排序 → 检查 max–min → 选集 → 平均。
CIE 9701/33/O/N/24 Q2(b)
(b) From your accurate titration results calculate a suitable mean value to be used in your calculations. Show clearly how you obtained the mean value. 25.0 cm³ of FA 3 required .............................. cm³ of FA 4. [1]
平均在 0.20 cm³ 内的 titre；2 d.p.；展示选取过程。
[M] MS 9701_w24_ms_33 2(b)：average of titres within 0.20 cm³; mean to 2 d.p.
CIE 9701/34/O/N/24 Q1(b)
(b) From your accurate titration results, calculate a suitable mean value to be used in your calculations. Show clearly how you obtained this value. 25.0 cm³ of FB 1 required .............................. cm³ of FB 2. [1]
同结构；FB 1 / FB 2 对应碘–硫代体系。
[M] 9701_w24_qp_34。
3–4 s.f. envelope
📖 Definition9701/33 Q2(c)(i)：若 (c)(ii)–(iv) 任一为错误 s.f.，该 envelope 分丢失。
🔑 Key9701/33 Q1(b)：质量与 M_r 常 2–4 s.f.。
🎯 Exam focus勿在链式中间过早四舍五入。
🛠️ Technique誊卷前统一检查三位或四位。
CIE 9701/33/O/N/24 Q2(c)(i)
(c) (i) Give your answers to (c)(ii), (c)(iii) and (c)(iv) to the appropriate number of significant figures. [1]
(c)(ii)–(iv) 全部 3 或 4 s.f. 才得该 1 分。
[M] MS 9701_w24_ms_33 2(c)(i).
CIE 9701/34/O/N/24 Q1(c)(i)
(c) (i) Give your answers to each part of (c)(ii) and (c)(iii) to an appropriate number of significant figures. [1]
碘速率卷类似 envelope（见该卷 MS）。
[M] 9701_w24_qp_34 Q1(c)(i)。
7. Crucible & decomposition
Crucible, lid & heating cycles（坩埚加热）
📖 Definition带盖冷却至少 5 min；强热时 lid off；恒重思路：重复加热–冷却–称量。
🔑 Key冷却时可用时间开始做其他题（卷面允许）。
🎯 Exam focuspipe-clay triangle；strong heating 时间按卷面。
🛠️ Technique记录每次 crucible + lid + contents 质量序列。
CIE 9701/34/O/N/24 Q2(a) method
Weigh the empty crucible with its lid. Record the mass. Transfer all of FB 4 into the crucible. Weigh the crucible, lid and FB 4. Record the mass. … Heat the crucible gently, with the lid on, for approximately 1 minute. Heat strongly, with the lid off, for a further 4 minutes. Replace the lid and leave the crucible to cool for at least 5 minutes.
顺序：空坩埚+盖 → 加盐 → 弱热加盖 → 强热开盖 → 冷却 ≥5 min → 称量；可重复至恒重。
[M] 9701_w24_qp_34 Q2(a) [5] 方法框架。
CIE 9701/34/O/N/24 Q2(a)
While the crucible is cooling, you may wish to begin work on Question 3.
时间管理：冷却窗口用于其他题（与 9701/33 Q1 等待 15 min 同理）。
[M] QP 原文。
mol H₂O lost & M<sub>r</sub> of MA₂
📖 Definitionn(\mathrm{H_2O})=\Delta m/18；由 M(\mathrm{MA_2}) 与卤素离子检验共同推断 M^{2+}。
🔑 Key9701/34 Q2(b)–(d) 链：水量 → M_r(\mathrm{MA_2}) → 卤素 → M^{2+}。
🎯 Exam focusQ2(e) 补加热不足对 (b) 与离子判断的影响（见节点 13/14）。
🛠️ Technique写清 residue 为 anhydrous salt。
CIE 9701/34/O/N/24 Q2(b)
(b) Calculate the amount, in mol, of water lost. amount of H₂O = .............................. mol Hence calculate the relative formula mass, Mr, of MA₂. Mr of MA₂ = .............................. [2]
n=m/18；再用盐组成求 M_r(\mathrm{MA_2})（与考生数据一致）。
[M] 见 9701_w24_ms_34 Q2(b)（本地 MS md）。
CIE 9701/34/O/N/24 Q2(d)
(d) Using your answers to (b) and (c), identify the ion M²⁺. M²⁺ is .............................. [1]
结合 M_r 与 A⁻ 检验结果推断 Group 2 金属。
[M] QP 逻辑。
8. Thermometric graphs
Table 1.1 temperature data
📖 Definition每次加酸后记录 **maximum** temperature；9 个体积点。
🔑 KeyMS：读数末位 .0 或 .5 °C；与 supervisor \delta\le 2.0 / \le 1.0\ °\mathrm{C}。
🎯 Exam focus0.00 cm³ 对应初温。
🛠️ Technique搅拌后读最高温。
CIE 9701/31/O/N/24 Q1(a) method
Pipette 25.0 cm³ of FA 1 into the cup. … Record the temperature of FA 1 in Table 1.1. This is the temperature when the volume of FA 2 is 0.00 cm³. … After each addition of FA 2 stir the contents of the cup. Record the maximum temperature for each addition. [4]
九个体积点均有 max T；末位 .0/.5；与 supervisor 比对。
[M] MS 9701_w24_ms_31 1(a) I–IV。
CIE 9701/31/O/N/24 Q1(a) Table 1.1
Table 1.1 — total volume of FA 2 / cm³: 0.00, 5.00, … 40.00 ; temperature / °C
表头须含名称与单位；体积由滴定管累计。
[M] QP Table 1.1。
Graph & intersection
📖 Definitiony 轴含比 T_\mathrm{max} 高约 3 °C 的刻度；两条 best line 外推交点。
🔑 Key上升段 smooth curve；下降段 straight or smooth；交点体积 1 d.p. cm³。
🎯 Exam focusLabel anomalous points。
🛠️ Technique交点横坐标 = neutralise 所需 V(\mathrm{FA\,2})。
CIE 9701/31/O/N/24 Q1(b)
(b) Plot a graph of temperature of solution (y-axis) against total volume of FA 2 added (x-axis) on the grid. Select a scale for the y-axis to include a value 3 °C above your maximum temperature reading. Label any points you consider to be anomalous. Draw two lines of best fit through the points on your graph. Draw the first line for the increase in temperature and the second line after the maximum temperature was reached. Extrapolate the lines so they intersect. This intersection corresponds to the volume of FA 2 needed to neutralise the FA 1 in your experiment in (a). 25.0 cm³ of FA 1 required .............................. cm³ of FA 2. [5]
按 MS I–V：轴、点、两线、外推、交点读数。
[M] MS 9701_w24_ms_31 1(b) I–V。
CIE 9701/31/O/N/24 Q1(b)
(same part) … 25.0 cm³ of FA 1 required .............................. cm³ of FA 2.
交点横坐标填入空格（1 d.p.）。
[M] MS 1(b) V。
9. Thermometric stoichiometry
Moles NaOH pipetted
📖 Definitionn=cV，V=25.0/1000\ \mathrm{dm^3}。
🔑 KeyMS 数值示例 25.0\times2.01/1000。
🎯 Exam focus3–4 s.f.。
🛠️ Technique用题目给的 2.01\ \mathrm{mol\,dm^{-3}}。
CIE 9701/31/O/N/24 Q1(c)(i)
(c) (i) Calculate the amount, in mol, of sodium hydroxide, FA 1, pipetted into the cup. amount of NaOH = .............................. mol [1]
25.0\times2.01/1000\ \mathrm{mol}（3 或 4 s.f.）。
[M] MS 9701_w24_ms_31 1(c)(i).
CIE 9701/31/O/N/24 Q1(c)(ii)
(ii) The equation for this neutralisation reaction is shown. 2NaOH(aq) + H₂SO₄(aq) → Na₂SO₄(aq) + 2H₂O(l). Calculate the concentration, in mol dm⁻³, of sulfuric acid in FA 2. Show your working. concentration of H₂SO₄ = .............................. mol dm⁻³ [2]
M1 n(\mathrm{H_2SO_4})=(\mathrm{c})(\mathrm{i})/2；M2 c=n\times1000/V 用交点体积。
[M] MS 9701_w24_ms_31 1(c)(ii).
c(H₂SO₄) from graph titre
📖 Definition用图中交点 V(\mathrm{FA\,2}) 与 n(\mathrm{NaOH})、方程式系数求 c(\mathrm{H_2SO_4})。
🔑 Key\mathrm{H_2SO_4} ~ 2 \mathrm{NaOH}。
🎯 Exam focusShow your working（题干）。
🛠️ Technique单位 mol dm⁻³；3–4 s.f.。
CIE 9701/31/O/N/24 Q1(c)(ii)
(ii) The equation for this neutralisation reaction is shown. 2NaOH(aq) + H₂SO₄(aq) → Na₂SO₄(aq) + 2H₂O(l). Calculate the concentration, in mol dm⁻³, of sulfuric acid in FA 2. Show your working. concentration of H₂SO₄ = .............................. mol dm⁻³ [2]
见上 MS M1+M2；V 来自 (b) 交点。
[M] MS 9701_w24_ms_31 1(c)(ii).
CIE 9701/31/O/N/24 Q1(b)–(c) link
This intersection corresponds to the volume of FA 2 needed to neutralise the FA 1 in your experiment in (a).
解释为何用外推交点而非单纯最高温点：对应计量中和（实验思想）。
[M] QP 9701_w24_qp_31 Q1(b) 原文。
10. I₂ / thiosulfate titration
Starch & colourless end-point
📖 Definition\mathrm{I_2}+2\mathrm{S_2O_3^{2-}}\rightarrow 2\mathrm{I^-}+\mathrm{S_4O_6^{2-}}；终点 **colourless**。
🔑 KeyYellow 时再加淀粉，避免包裹。
🎯 Exam focus用 colourless 不用模糊 clear。
🛠️ Technique近终点半滴。
CIE 9701/34/O/N/24 Q1(a) method
Run FB 2 into the conical flask until the colour of the solution turns yellow. Then add 10 drops of FB 3. The solution will turn blue-black. The end-point of the titration is when the solution turns colourless.
黄 → 淀粉 → 蓝黑 → 滴至无色。
[M] 9701_w24_qp_34。
CIE 9701/34/O/N/24 Q1 intro
I₂(aq) + 2S₂O₃²⁻(aq) → 2I⁻(aq) + S₄O₆²⁻(aq)
计量比 1 : 2 用于 (c)(ii) 计算。
[M] QP reaction line。
Rough + accurate titres
📖 DefinitionRough titre 单独记录；准确滴定多次至一致。
🔑 KeyMS 9701/33 2(a) I：rough 两读数 + titre；准确滴定 initial/final。
🎯 Exam focusPrecision of practical work。
🛠️ Technique与碳酸盐滴定、碘滴定结构相同。
CIE 9701/34/O/N/24 Q1(a)
Perform a rough titration and record your burette readings in the space below. The rough titre is .............................. cm³. Carry out as many accurate titrations as you think necessary to obtain consistent results.
先粗后精；与 MS 记录项一致。
[M] 9701_w24_qp_34。
CIE 9701/33/O/N/24 Q2(a)
Perform a rough titration and record your burette readings in the space below. The rough titre is .............................. cm³. Carry out as many accurate titrations as you think necessary to obtain consistent results.
同结构（FA 3 / FA 4）。
[M] 9701_w24_qp_33 Q2(a)。
11. Rate via titre chain
Quench & dilute to 150 cm³
📖 Definition\mathrm{NaHCO_3} 除尽样中 \mathrm{H_2SO_4}；定容 150.0\ \mathrm{cm^3} 得 \mathrm{FB\,1}。
🔑 Key起始混合总体积 200\ \mathrm{cm^3}；取样 25.0\ \mathrm{cm^3}。
🎯 Exam focus80 s 时刻加碳酸氢盐（题干）。
🛠️ Technique稀释因子带入 (c)(ii)–(iv)。
CIE 9701/34/O/N/24 Q1 intro
The student removes 25.0 cm³ of the solution. After 80 seconds, 50.0 cm³ of a solution of sodium hydrogencarbonate, NaHCO₃, is added which reacts with all the sulfuric acid in the sample. Distilled water is added until the volume of the solution is 150.0 cm³. This solution is FB 1.
骤停酸催化；定容体积用于反算原混合物中 \mathrm{I_2}。
[M] 9701_w24_qp_34。
CIE 9701/34/O/N/24 Q1 intro
A student studies this reaction by mixing together the following three solutions and immediately starting the stop-clock. • 100.0 cm³ of 0.1000 mol dm⁻³ iodine, I₂ • 50.0 cm³ of 1.00 mol dm⁻³ propanone, CH₃COCH₃ • 50.0 cm³ of 1.00 mol dm⁻³ sulfuric acid, H₂SO₄
总 200 cm³ 混合；用于浓度稀释推导。
[M] QP 起始体积。
Average rate formula
📖 Definition卷面：\text{average rate}=\dfrac{\text{change in the concentration of }\mathrm{I_2}}{\text{time}}。
🔑 Key(c)(iii)(iv) 链 + 若 (c)(iii) 失败可用备用浓度。
🎯 Exam focus单位：value + units 分两格。
🛠️ Technique由 titre \rightarrow n(\mathrm{S_2O_3^{2-}}) \rightarrow n(\mathrm{I_2}) in 150 cm³ \rightarrow [\mathrm{I_2}] in sample \rightarrow initial [\mathrm{I_2}] in 200 cm³。
CIE 9701/34/O/N/24 Q1(c)(iv)
(iv) Calculate the initial concentration of iodine in the reaction mixture. (If you were unable to determine an answer to (c)(iii) use 0.0315 mol dm⁻³ as the concentration of I₂ in the sample the student removed.) initial concentration of I₂ = .............................. mol dm⁻³ Hence calculate the average rate of reaction during the first 80 seconds using the formula shown. average rate of reaction = (change in the concentration of I₂) / time average rate = ........................ ........................... value units [2]
先 [\mathrm{I_2}]_0，再 \Delta[\mathrm{I_2}]/80\ \mathrm{s}；单位随定义。
[M] 9701_w24_qp_34 原文公式排版。
CIE 9701/34/O/N/24 Q1(c)(ii)
(ii) Use your answer to (b) to calculate the amount, in mol, of thiosulfate ions in your mean titre. amount of S₂O₃²⁻ = .............................. mol Hence calculate the amount, in mol, of iodine present in the total volume of 150.0 cm³ that the student prepares. amount of I₂ = .............................. mol [2]
n(\mathrm{S_2O_3^{2-}})=cV；n(\mathrm{I_2})=n(\mathrm{S_2O_3^{2-}})/2 于 150 cm³ 溶液。
[M] QP + MS 逻辑。
12. Qualitative analysis
Observations & no change
📖 DefinitionExamples of observations include: colour changes; ppt + solubility in excess; gas + test。Where no change is observed, you should write ‘no change’。
🔑 Key记录阶段：at what stage…
🎯 Exam focus试剂名称或正确化学式。
🛠️ Technique表格测试如 Table 3.1 逐行完整。
CIE 9701/33/O/N/24 Q3 (Qualitative Analysis intro)
For each test you should record all your observations in the spaces provided. Examples of observations include: • colour changes seen • the formation of any precipitate and its solubility (where appropriate) in an excess of the reagent added • the formation of any gas and its identification (where appropriate) by a suitable test. You should record clearly at what stage in a test an observation is made. Where no change is observed, you should write ‘no change’. Where reagents are selected for use in a test, the name or correct formula of the element or compound must be given.
按卷面四类信息书写；无现象写 no change。
[M] 9701_w24_qp_33 Q3 卷首。
CIE 9701/33/O/N/24 Q3(a)(i)
(a) (i) FA 6 contains one cation and one anion both of which are listed in the Qualitative analysis notes. Heat a small spatula measure of FA 6 in a hard-glass test-tube, until no further change occurs. Record all your observations. Identify any gas produced. [3]
硬玻璃试管；记录加热过程颜色/气体等。
[M] QP + MS 观察分。
Hard-glass tube & reuse
📖 DefinitionIf any solution is warmed, a boiling tube must be used. If a solid is heated, a hard-glass test-tube must be used. Rinse and reuse test-tubes and boiling tubes where possible. No additional tests should be attempted.
🔑 Key安全 + 减废 + 不超纲额外检验。
🎯 Exam focus与 (a)(i) solid heating 指令一致。
🛠️ TechniqueBoiling tube vs test-tube 按物态选。
CIE 9701/33/O/N/24 Q3 intro
If any solution is warmed, a boiling tube must be used. If a solid is heated, a hard-glass test-tube must be used. Rinse and reuse test-tubes and boiling tubes where possible. No additional tests should be attempted.
固体强热 → hard-glass test-tube；勿加做未要求检验。
[M] 9701_w24_qp_33。
CIE 9701/33/O/N/24 Q3(a)(iii)
(iii) Give the equation for the reaction in (a)(ii). Include state symbols. [1]
按 residue 与稀硫酸反应写方程式；须含 state symbols。
[M] QP 指令。
13. Starch & sampling critique
Why starch at yellow
📖 Definition避免高 [\mathrm{I_2}] 时淀粉包裹碘/封闭终点导致硫代硫酸盐消耗不准。
🔑 Key常用答案：starch–iodine complex strongly adsorbed / trapped I₂ / endpoint hard to detect if added at start（与 MS 可接受表述一致）。
🎯 Exam focusQ 为卷面原句。
🛠️ Technique对比 “at start” vs “when yellow”。
CIE 9701/34/O/N/24 Q1(d)
(d) Suggest why the starch solution is added when the solution in the conical flask turns yellow and not added at the start of the titration. [1]
高碘浓度下淀粉–碘络合物吸附/包裹使终点拖尾或硫代硫酸根局部过量反应；黄时 [\mathrm{I_2}] 已较低。
[M] 见 9701_w24_ms_34 Q1(d)（本地 MS）。
CIE 9701/34/O/N/24 Q1(a) method
Run FB 2 into the conical flask until the colour of the solution turns yellow. Then add 10 drops of FB 3.
操作与 (d) 理论呼应：先大部反应再指示剂。
[M] QP 方法。
Remove sample vs add NaHCO₃ at 80 s
📖 Definition讨论“取样移出”与“原地加淬灭剂”对反应体积、浓度时间线的影响。
🔑 Key须 State if you agree … Explain（卷面指令）。
🎯 Exam focusAgree / disagree 均可，论证自洽即得分。
🛠️ Technique引用混合物体积恒定 vs 取样后体系变化。
CIE 9701/34/O/N/24 Q1(e)
(e) A student suggests that the experimental procedure is incorrect. The student says that the sample should be removed from the reaction mixture at 80 seconds rather than the sodium hydrogencarbonate being added at 80 seconds. State if you agree with this student. Explain your answer. [1]
常见：不同意——因移出样品会改变总体积/浓度基准或引入取样时间误差；或同意并给出另一合理实验论证。
[M] 9701_w24_ms_34 Q1(e)（本地 MS）。
CIE 9701/34/O/N/24 Q1 intro
In this experiment you will determine the concentration of iodine in FB 1 and so determine the average rate of reaction during the first 80 seconds.
实验目的绑定 80 s 内平均速率定义。
[M] QP aim 句。
14. Halide plan & exam rules
Tests for A⁻ in MA₂
📖 DefinitionCarry out tests to identify the halide present in MA₂. Record the reagents used, the results of your tests and the identity of A⁻。
🔑 Key与 (b)(c)(d) 数据联立推断 M^{2+}。
🎯 Exam focusQ2(e) 另问加热不足对 (b) 与为何仍可能认出 M^{2+}。
🛠️ Technique按 Qualitative analysis notes 选试剂。
CIE 9701/34/O/N/24 Q2(c)
(c) FB 5 is a solution of the hydrated salt MA₂. The A⁻ ion is a halide. Carry out tests to identify the halide present in MA₂. Record the reagents used, the results of your tests and the identity of A⁻. A⁻ is .............................. [2]
沉淀/溶解性 + 硝酸银等（按卷面 notes）；写清 reagents 与 observations。
[M] QP 9701_w24_qp_34。
CIE 9701/34/O/N/24 Q2(e)
(e) A student correctly identifies A⁻ but did not heat the sample of FB 4 for long enough to remove all the water of crystallisation. Despite this error, the student still correctly identifies M²⁺. Explain how the student’s answer in (b) would differ from the true answer. Explain why the student still correctly identifies M²⁺.
(b) n(\mathrm{H_2O}) 偏大 → M_r 偏小；若 M_r 仍在两离子决策区间内仍可判对 M^{2+}（与 MS 思路一致）。
[M] QP 9701_w24_qp_34 Q2(e)。
ecf, units & alternate \(x\) design
📖 Definitionecf：后续科学正确使用错误前体仍可给分。List rule：只取前 n 条非矛盾答案。另：无酸法测结晶水 x 为常见开放设计。
🔑 Key缺单位常导致末位计算分不授（MS 总则）。
🎯 Exam focusQ2(d) 两格：method + accuracy；与 Q2(v) x 计算衔接。
🛠️ Techniqueecf 段落与 QP 设计题分开展示：Mark 区引用 MS 原文。
CIE 9701/33/O/N/24 Q2(d) (QP)
(d) Describe a different method to determine the value of x in FA 1. This method should not involve the reaction of an acid. Explain how the method will ensure that the value of x is as accurate as possible. [2]
加热至恒重测失水；干燥器冷却称量；慢热防溅——与方案自洽。
[M] MS 9701_w24_ms_33 Q2(d)（开放题）。
CIE 9701/33/O/N/24 Q2(v) (QP)
(v) The metal carbonate in FA 1 is hydrated sodium carbonate, Na₂CO₃•xH₂O. Calculate the value of x to the nearest whole number. Show your working. x = .............................. [1]
与滴定链所得 M_r 衔接求 x（考生数据）。
[M] QP 9701_w24_qp_33 Q2(v)。
MS 9701_w24_ms_33 (ecf principle)
(Marking scheme) 4 The error carried forward (ecf) principle should be applied, where appropriate. If an incorrect answer is subsequently used in a scientifically correct way, the candidate should be awarded these subsequent marking points.
ecf 适用场景（MS 文首原则，非考生卷面题干）。
[M] MS 9701_w24_ms_33 Science-Specific Marking Principles。
MS 9701_w24_ms_31 (units in calculations)
(Marking scheme) 6 Unless a separate mark is given for a unit, a missing or incorrect unit will normally mean that the final calculation mark is not awarded.
单位与末分关系（MS 总则，非 QP）。
[M] MS 9701_w24_ms_31 Calculation specific guidance。