OCR AS Level · Analysis & Prediction

2024 OCR AS Level Chemistry B (Salters) - H033 Past Paper Analysis

The June 2024 OCR AS Chemistry B (Salters) suite represents a balanced but demanding assessment, testing core foundations in Paper 1 and challenging conceptual/analytical depth in Paper 2. Key differentiators included multi-step stoichiometry, spectroscopy interpretation, and rigorous physical chemistry applications.

Updated: 14 Jun 2026

Analysis Sample paper

Difficulty 3.8/5

Total marks

140

Duration

180 mins

Most tested

Inorganic Halogen Chemistry and Redox

Paper breakdown

H033/01 Foundations of chemistry: 70 marks · 90 minsH033/02 Chemistry in depth: 70 marks · 90 mins

Top chapters

Inorganic chemistry and the periodic table (Elements from the sea (ES)) · 14 marksEquilibria (Elements from the sea (ES)) · 13 marksFormulae, equations and amount of substance (Developing fuels (DF)) · 11 marks

Overall Exam Verdict

The June 2024 OCR AS Chemistry B (Salters) examination papers (H033/01 and H033/02) delivered a comprehensive and rigorous evaluation of the specifications. Paper 1 (Foundations of Chemistry) offered a solid mix of straightforward recall and multi-step calculations, while Paper 2 (Chemistry in Depth) pushed students to apply concepts in less familiar contexts. The inclusion of two 6-mark extended-response questions (organic structure elucidation and gas syringe equilibria) elevated the overall difficulty, making this a challenging but fair assessment of a student's true chemical literacy.

Where the Marks Were Won and Lost

High-scoring candidates demonstrated precision in fundamental chemical skills. Marks were easily secured in the multiple-choice section of Paper 1 and on basic nomenclature. However, many students dropped critical marks on the following:

Mechanism Precision: Curly arrows in nucleophilic substitution must start exactly from the lone pair of the nucleophile \( (:\text{I}^-) \) and end directly on the electrophilic carbon.
Calorimetry and Signs: Calculating thermodynamic values was generally well done, but omitting the negative sign for exothermic enthalpy changes \( (\Delta H_1 = -35\text{ kJ mol}^{-1}) \) was a frequent pitfall.
Ideal Gas Equation Conversions: In the calculation of \( M_r \), failing to convert volume from \( \text{cm}^3 \) to \( \text{m}^3 \) prevented students from achieving full marks.

Strategic Advice for Future Cohorts

To excel in Salters Chemistry, memorisation is not enough; practical and mathematical fluency are key. Focus on these three pillars:

Master Spectroscopy Logic: In 6-mark spectroscopy questions, use a structured approach. State what is present (e.g., \( \text{C=O} \) at \( 1750\text{ cm}^{-1} \)) AND explicitly rule out what is absent (e.g., no \( \text{O-H} \) peak at \( 2500\text{-}3600\text{ cm}^{-1} \) rules out carboxylic acids).
Equilibria Explanations: When explaining shifts in equilibria, structure your answer using Le Chatelier's principle step-by-step: identify the stress, state the direction of the shift to oppose this change, and conclude with the effect on concentration/yield.
Skeletal Structures: Practice drawing clean, unambiguous skeletal formulas, especially for monomers and branched alkanes.

Projections & Predictions

An analysis of historical cycles shows that topics like Kinetics (The Ozone Story) and Organic Functional Groups (What's in a Medicine?) had lower relative exposure in this series. Future papers are highly likely to feature an increased emphasis on transition metal chemistry, radical chain mechanisms, and multi-step synthetic pathways.

Charts

Marks by chapter

See where the marks were concentrated so revision time goes to the highest-value topics.

Question type mix

Compare the mark share of each paper section and question type.

Multiple Choice (MCQ)20 marks · 20 questions
Short Answer (SAQ)108 marks · 35 questions
Extended Response (LOR)12 marks · 2 questions

Mark accessibility

Estimate which marks were basic, mid-level, or high-difficulty.

79%within easy or medium reach

easy: 45 marksmedium: 65 markshard: 30 marks

Difficulty trend

Compare difficulty across recent years.

Command word frequency

Spot common command words so answers match the expected response style.

Skill weighting

Shows the skill mix this paper tested most heavily.

Study ROI

Bigger bubbles recur more often; higher bubbles carry more marks, helping you rank revision priorities.

Inorganic chemistry and the periodic table (Elements from the sea (ES))

14 marks · Difficulty 2.5 · recurrence 5%

Formulae, equations and amount of substance (Developing fuels (DF))

11 marks · Difficulty 3 · recurrence 4%

Inorganic chemistry and the periodic table (Elements of life (EL))

9 marks · Difficulty 2.8 · recurrence 4%

Equilibria (Elements from the sea (ES))

13 marks · Difficulty 3.5 · recurrence 4%

Energetics (Developing fuels (DF))

8 marks · Difficulty 3.2 · recurrence 4%

Time vs marks

Compare marks with suggested time allocation to plan exam pacing.

marksmins

Next-year prediction

Topics worth watching next year, with the reason shown directly below each bar.

Organic functional groups (What’s in a medicine? (WM))85%

Scarcely tested in this series, leaving functional group transformations of salicylates and medicinal compounds highly overdue for a main structured question.

Kinetics (The ozone story (OZ))78%

Radical-controlled kinetics and rate equations were minimally covered in 2024, predicting a heavy emphasis in upcoming assessments.

Topic-year heatmap

Compare topic weight by year to spot recurring and returning areas.

Jun 2022

Jun 2023

Jun 2024

Atomic structure (Elements of life (EL))

Bonding and structure (Developing fuels (DF))

Bonding and structure (Elements of life (EL))

Organic functional groups (Developing fuels (DF))

Formulae, equations and amount of substance (Developing fuels (DF))

Inorganic chemistry and the periodic table (Elements from the sea (ES))

Organic reactions (What’s in a medicine? (WM))

Modern analytical techniques (What’s in a medicine? (WM))

Formulae, equations and amount of substance (Elements of life (EL))

Organic reactions (Developing fuels (DF))

Examiner insights

Official report

Common pitfalls

Drawing nucleophilic substitution mechanisms where the curly arrow originates from the negative charge on the iodide ion rather than specifically from the lone pair.
Omitting necessary negative signs in final calorimetry enthalpy calculation steps despite correctly determining temperature changes and heat output.
Omitting key structural proofs in spectroscopy extended questions, particularly failing to cite the absence of the broad carboxylic acid O-H absorption band.

Misconceptions

Believing that gas syringe compression immediately drives equilibrium to a lighter color without appreciating that compression initially increases concentrations (and darkness) of all species before Le Chatelier's shift takes effect.
Assuming that the first ionisation energy of halogens is the highest in their period, confusing group trends with period trends.

Where marks are lost

Failing to convert volume units in ideal gas equation problems (leaving cubic centimeters unconverted to cubic meters).
Uncertainty calculations where students fail to link the absolute measurement uncertainty of 0.05g to the total mass used of 2.0g.
Incorrectly identifying reflux mistakes, such as not recognizing that the top of the condenser must remain open and unsealed.

Estimated grade cut-off

Updated: 15 Jun 2026

Source: OCR

Level	Mark	Percentage
A	93/140	66%
B	79/140	56%
C	65/140	46%
D	51/140	36%
E	38/140	27%

Official grade boundaries published by OCR.

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