CHEMISTRY-YCH11 · Pearson Edexcel International A Level
CHEMISTRY-YCH11/11
Paper 1
Chemistry · June 2025 · Variant 1
Relative difficulty
Analysis source: Pearson Edexcel
Analysis aligned to the official syllabus and assessment design.
3.8 / 5
440
550 min
Coordination Chemistry & Transition Metal Complexes
Cohort performance
Session statistics from official examination reports
Total marks
440
Duration
550 min
Session difficulty
3.8 / 5
Key examiner messages
Top priorities from the principal examiner before you revise
Excellent performances were noted in calculation-heavy sections where candidate pathways were clearly structured, such as ideal gas evaluations pV=nRT pV = nRT pV=nRT and empirical formula determinations.
However, substantial marks were lost in descriptive questions demanding absolute precision.
In Unit 1 (WCH11), a surprising number of students failed to include correct state symbols in the third ionisation energy equation of calcium, writing Ca2+→Ca3++e− \text{Ca}^{2+} \rightarrow \text{Ca}^{3+} + \text{e}^- Ca2+→Ca3++e− without the mandatory gaseous notations.
In Unit 2 (WCH12), percentage uncertainty calculations often fell victim to a recurring examiner pitfall: forgetting to double the thermometer's single-reading uncertainty of ±0.5 ∘C \pm 0.5\,^{\circ}\text{C} ±0.5∘C when determining a temperature change.
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
Weight: 9100%Organic
Weight: 889%Mechanism
Weight: 778%Logical
Weight: 667%Scientifi
Weight: 556%Practical Techniques
Weight: 444%Enthalpy &
Weight: 222%Entrop
Weight: 111%
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. 90% of maximum mark
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 “State” questions.
Match the expected response style for “Draw” questions.
State features in sequence or list observable properties — do not explain causes unless asked.
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 “Deduce” questions.
Time traps
Sections where candidates spent disproportionate time relative to marks
Min per mark: 1.3
Min per mark: 1.3
Min per mark: 1.2
Syllabus traceability
Topics linked to questions and mark weighting in this session
Transition Metals and their Chemistry
48 marks this session
Organic Nitrogen Compounds: Amines, Amides, Amino Acids and Proteins
42 marks this session
Organic Chemistry: Alcohols, Halogenoalkanes and Spectra
38 marks this session
Bonding and Structure
36 marks this session
Formulae, Equations and Amount of Substance
34 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
Formulae, Equations and Amount of Substance
Transition Metals and their Chemistry
Organic Chemistry: Alcohols, Halogenoalkanes and Spectra
Organic Chemistry: Carbonyls, Carboxylic Acids and Chirality
Organic Nitrogen Compounds: Amines, Amides, Amino Acids and Proteins
Organic Synthesis
Kinetics (Rates, Equilibria and Further Organic Chemistry)
Bonding and Structure
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: WCH14/01 Unit 4: Rates, Equilibria and Further Organic Chemistry: WCH15/01 Unit 5: Transition Metals and Organic Nitrogen Chemistry: WCH16/01 Unit 6: Practical Skills in Chemistry II:
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
Transition Metals and their Chemistry
48 marks this session
Practise in RevuiOrganic Nitrogen Compounds: Amines, Amides, Amino Acids and Proteins
42 marks this session
Practise in RevuiOrganic Chemistry: Alcohols, Halogenoalkanes and Spectra
38 marks this session
Practise in RevuiBonding and Structure
36 marks this session
Practise in RevuiFormulae, Equations and Amount of Substance
34 marks this session
Practise in RevuiSelf-diagnostic checklist
Key actions before you sit this paper — copy and tick off as you revise
- 1Message
Excellent performances were noted in calculation-heavy sections where candidate pathways were clearly structured, such as ideal gas evaluations pV=nRT pV = nRT pV=nRT and empirical formula determinations.
- 2Message
However, substantial marks were lost in descriptive questions demanding absolute precision.
- 3Message
In Unit 1 (WCH11), a surprising number of students failed to include correct state symbols in the third ionisation energy equation of calcium, writing Ca2+→Ca3++e− \text{Ca}^{2+} \rightarrow \text{Ca}^{3+} + \text{e}^- Ca2+→Ca3++e− without the mandatory gaseous notations.
- 4Message
In Unit 2 (WCH12), percentage uncertainty calculations often fell victim to a recurring examiner pitfall: forgetting to double the thermometer's single-reading uncertainty of ±0.5 ∘C \pm 0.5\,^{\circ}\text{C} ±0.5∘C when determining a temperature change.
Teacher briefing pack
One-page session summary for tutors and classroom review
June 2025 2025
Chemistry
Excellent performances were noted in calculation-heavy sections where candidate pathways were clearly structured, such as ideal gas evaluations pV=nRT pV = nRT pV=nRT and empirical formula determinations. However, substantial marks were lost in descriptive questions demanding abs
Excellent performances were noted in calculation-heavy sections where candidate pathways were clearly structured, such as ideal gas evaluations pV=nRT pV = nRT pV=nRT and empirical formula determinations.
However, substantial marks were lost in descriptive questions demanding absolute precision.
In Unit 1 (WCH11), a surprising number of students failed to include correct state symbols in the third ionisation energy equation of calcium, writing Ca2+→Ca3++e− \text{Ca}^{2+} \rightarrow \text{Ca}^{3+} + \text{e}^- Ca2+→Ca3++e− without the mandatory gaseous notations.
- Total marks
- 440
- Duration
- 550 min
- Session difficulty
- 3.8 / 5
Session analysis
Excellent performances were noted in calculation-heavy sections where candidate pathways were clearly structured, such as ideal gas evaluations pV=nRT pV = nRT pV=nRT and empirical formula determinations. However, substantial marks were lost in descriptive questions demanding absolute precision. In Unit 1 (WCH11), a surprising number of students failed to include correct state symbols in the third ionisation energy equation of calcium, writing Ca2+→Ca3++e− \text{Ca}^{2+} \rightarrow \text{Ca}^{3+} + \text{e}^- Ca2+→Ca3++e− without the mandatory gaseous notations. In Unit 2 (WCH12), percentage uncertainty calculations often fell victim to a recurring examiner pitfall: forgetting to double the thermometer's single-reading uncertainty of ±0.5 ∘C \pm 0.5\,^{\circ}\text{C} ±0.5∘C when determining a temperature change.
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: WCH14/01 Unit 4: Rates, Equilibria and Further Organic Chemistry: WCH15/01 Unit 5: Transition Metals and Organic Nitrogen Chemistry: WCH16/01 Unit 6: Practical Skills in Chemistry II:
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.
80% 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
(Section B)
254·56·58%
Extended Writing & Contextual
(Section C)
106·16·24%
Multiple Choice
(Section A)
80·80·18%
Study ROI
Bigger bubbles recur more often; higher bubbles carry more marks, helping you rank revision priorities.
Difficulty trend
Compare difficulty across recent years.
Time vs marks
Compare marks with suggested time allocation to plan exam pacing.
Section A (Multiple
0.80 m/minSection B (Structur
0.81 m/minSection C (Extended
0.79 m/minTotal marks
440
Total time
550 min
Avg pace
0.80
Next-year prediction
Topics worth watching next year, with the reason shown directly below each bar.
Acid-Base Indicators & Buffer Calculations
90%90%
Transition Metal Ligand Exchange and Stability Constants
85%85%
Synthesis of Azo Dyes and Coupling Reactions
80%80%
Analysis is paraphrased for study purposes. Always verify against the official examiner report and mark scheme.