CHEMISTRY-XCH11 · Pearson Edexcel International AS Level
CHEMISTRY-XCH11/21
Paper 2
Chemistry · Winter 2025 · Variant 1
Relative difficulty
Analysis source: Pearson Edexcel
Analysis aligned to the official syllabus and assessment design.
3.5 / 5
210
260 min
Formulae, Equations and Amount of Substance
Cohort performance
Session statistics from official examination reports
Total marks
210
Duration
260 min
Session difficulty
3.5 / 5
Key examiner messages
Top priorities from the principal examiner before you revise
In the physical chemistry sections, the gas law calculation pV=nRT pV = nRT pV=nRT was a major source of dropped marks, primarily due to incorrect conversions of volume from cubic decimeters to cubic meters.
In organic chemistry, candidates struggled to differentiate the dual roles of the hydroxide ion, often mislabeling it as a nucleophile in elimination reactions or a base in nucleophilic substitutions.
Additionally, drawing mechanisms remains a critical discriminator: missing the lone pair on the nucleophile or drawing incorrect arrowheads (single-headed instead of double-headed) cost students high-value marks.
In Unit 3, standard solution preparation descriptions frequently missed the crucial step of adding washings to the volumetric flask before making up to the mark.
Question difficulty map
How candidates performed on each question in this series
No data available in official reports
Assessment objectives
Skill and AO weighting from official examiner commentary
Skill weighting
Shows the skill mix this paper tested most heavily.
Mathematical & Calculation
Weight: 7100%Conceptual Understanding
Weight: 686%Practical
Weight: 457%Skills
Weight: 343%Trends and Periods
Weight: 229%Periodicity
Weight: 114%
Method marks watchlist
Where working, steps, or method marks were commonly lost
No data available in official reports
Recurring mistakes across years
Themes examiners flag in multiple recent sessions for this subject
No data available in official reports
Question choice intelligence
Mean scores and popularity for optional questions (HKDSE electives)
No data available in official reports
Level exemplars
What candidate scripts at each grade level looked like
No data available in official reports
Grade & admission context
How marks relate to grade thresholds and entry standards
Report type
Examiner report — national grade boundaries and question-level commentary
Level A
Approx. 80% of maximum mark
Level B
Approx. 70% of maximum mark
Level C
Approx. 60% of maximum mark
Level D
Approx. 50% of maximum mark
Level E
Approx. 40% of maximum mark
Deep insights
What top candidates did
Techniques and approaches examiners rewarded in this series
No data available in official reports
Command word playbook
How to match each command word to the expected response style
Show formula, substitution, and unit; method marks need visible working.
Give reasons and link mechanism to outcome; each point needs a because/so chain.
Match the expected response style for “Name” questions.
Match the expected response style for “Draw” questions.
Name or point to the specific feature asked for — avoid extra explanation.
Support your choice with specific evidence from data or the scenario given.
Match the expected response style for “contrast” questions.
Time traps
Sections where candidates spent disproportionate time relative to marks
No data available in official reports
Syllabus traceability
Topics linked to questions and mark weighting in this session
Formulae, Equations and Amount of Substance
49 marks this session
Organic Chemistry: Alcohols, Halogenoalkanes and Spectra
37 marks this session
Redox Chemistry and Groups 1, 2 and 7
22 marks this session
MCQ trap analytics
Commonly chosen wrong options from examiner commentary
No data available in official reports
Topic heatmap across years
Mark concentration by topic and exam year for this subject
Mark intensity
Organic Chemistry: Alcohols, Halogenoalkanes and Spectra
Formulae, Equations and Amount of Substance
Redox Chemistry and Groups 1, 2 and 7
Bonding and Structure
Difficulty trend
How session difficulty has shifted across recent years
Paper comparison
Marks and duration breakdown across papers in this session
WCH11/01 - Unit 1: Structure, Bonding and Introduction to Organic Chemistry: WCH12/01 - Unit 2: Energetics, Group Chemistry, Halogenoalkanes and Alcohols: WCH13/01 - Unit 3: Practical Skills in Chemistry I:
Marks you can still earn
Where valid approaches outside the mark scheme may still gain credit
No data available in official reports
Practise what examiners flagged
Target weak topics from this report inside the Revui app
Formulae, Equations and Amount of Substance
49 marks this session
Practise in RevuiOrganic Chemistry: Alcohols, Halogenoalkanes and Spectra
37 marks this session
Practise in RevuiRedox Chemistry and Groups 1, 2 and 7
22 marks this session
Practise in RevuiSelf-diagnostic checklist
Key actions before you sit this paper — copy and tick off as you revise
- 1Message
In the physical chemistry sections, the gas law calculation pV=nRT pV = nRT pV=nRT was a major source of dropped marks, primarily due to incorrect conversions of volume from cubic decimeters to cubic meters.
- 2Message
In organic chemistry, candidates struggled to differentiate the dual roles of the hydroxide ion, often mislabeling it as a nucleophile in elimination reactions or a base in nucleophilic substitutions.
- 3Message
Additionally, drawing mechanisms remains a critical discriminator: missing the lone pair on the nucleophile or drawing incorrect arrowheads (single-headed instead of double-headed) cost students high-value marks.
- 4Message
In Unit 3, standard solution preparation descriptions frequently missed the crucial step of adding washings to the volumetric flask before making up to the mark.
Teacher briefing pack
One-page session summary for tutors and classroom review
Winter 2025 2025
Chemistry
In the physical chemistry sections, the gas law calculation pV=nRT pV = nRT pV=nRT was a major source of dropped marks, primarily due to incorrect conversions of volume from cubic decimeters to cubic meters. In organic chemistry, candidates struggled to differentiate the dual rol
In the physical chemistry sections, the gas law calculation pV=nRT pV = nRT pV=nRT was a major source of dropped marks, primarily due to incorrect conversions of volume from cubic decimeters to cubic meters.
In organic chemistry, candidates struggled to differentiate the dual roles of the hydroxide ion, often mislabeling it as a nucleophile in elimination reactions or a base in nucleophilic substitutions.
Additionally, drawing mechanisms remains a critical discriminator: missing the lone pair on the nucleophile or drawing incorrect arrowheads (single-headed instead of double-headed) cost students high-value marks.
- Total marks
- 210
- Duration
- 260 min
- Session difficulty
- 3.5 / 5
Session analysis
In the physical chemistry sections, the gas law calculation pV=nRT pV = nRT pV=nRT was a major source of dropped marks, primarily due to incorrect conversions of volume from cubic decimeters to cubic meters. In organic chemistry, candidates struggled to differentiate the dual roles of the hydroxide ion, often mislabeling it as a nucleophile in elimination reactions or a base in nucleophilic substitutions. Additionally, drawing mechanisms remains a critical discriminator: missing the lone pair on the nucleophile or drawing incorrect arrowheads (single-headed instead of double-headed) cost students high-value marks. In Unit 3, standard solution preparation descriptions frequently missed the crucial step of adding washings to the volumetric flask before making up to the mark.
Updated Jun 12, 2026
Paper breakdown
WCH11/01 - Unit 1: Structure, Bonding and Introduction to Organic Chemistry: WCH12/01 - Unit 2: Energetics, Group Chemistry, Halogenoalkanes and Alcohols: WCH13/01 - Unit 3: Practical Skills in Chemistry I:
Top chapters
Exam structure insights
Marks by chapter
See where the marks were concentrated so revision time goes to the highest-value topics.
Mark accessibility
Estimate which marks were basic, mid-level, or high-difficulty.
76% within easy or medium reach
Command word frequency
Spot common command words so answers match the expected response style.
Question type mix
Compare the mark share of each paper section and question type.
Structured/Short Answer
170·11·81%
Multiple Choice
40·40·19%
Study ROI
Bigger bubbles recur more often; higher bubbles carry more marks, helping you rank revision priorities.
Next-year prediction
Topics worth watching next year, with the reason shown directly below each bar.
Group 2 Carbonates and Hydroxides Trends
88%88%
Redox Titrations (e.g. Fe2+ / Cr2O72- or Thiosulfate)
85%85%
Green Chemistry and Polymer Sustainability
80%80%
Analysis is paraphrased for study purposes. Always verify against the official examiner report and mark scheme.