IB Chemistry Paper 1A and 1B: How the Paper Works

By Michael Thompson · Education Specialist; 10 years teaching the IB at Bromsgrove School · Published 4 October 2026 · Updated 6 October 2026

IB Chemistry Paper 1B is the data-based and experimental-work section of Paper 1, sat in the same session as the multiple-choice Paper 1A. Together, Papers 1A and 1B run for 1 hour 30 minutes at SL and 2 hours at HL, and account for 36% of your final grade. Paper 1B was introduced with the revised course first assessed in May 2025, so the paper structure is genuinely new - older past papers can help with content knowledge and multiple-choice practice, but they are not a direct model for Paper 1B questions. This guide explains how both parts of Paper 1 work, what Paper 1B actually tests, and how to prepare effectively for each.

Key Takeaways

In This Article

  1. What Is IB Chemistry Paper 1B?
  2. Paper 1 Structure: Timings, Weightings and How 1A and 1B Fit Together
  3. What Does Paper 1B Actually Test?
  4. How to Approach Paper 1A: IB Chemistry Multiple-Choice Strategies
  5. How to Approach Paper 1B: Reading Data, Processing Results and Evaluating Methods
  6. Using Past Papers and the IB Chemistry Data Booklet Effectively
  7. Revision Strategy for Both Papers
  8. What to Do Next

1. What Is IB Chemistry Paper 1B?

IB Chemistry Paper 1B is the data-based questions and experimental-work section of IB Chemistry Paper 1, first assessed in May 2025 under the revised course organised into Structure and Reactivity. It sits in the same session as Paper 1A, which is the multiple-choice section, so you complete both parts within a single block of exam time: 1 hour 30 minutes at SL or 2 hours at HL. Paper 1 as a whole is worth 36% of your final grade at both levels, per the IB Chemistry subject brief.

The distinction between the two parts matters. Paper 1A tests recall and conceptual understanding through multiple-choice questions. Paper 1B does something different: it presents unfamiliar stimulus material, typically graphs, tables, experimental descriptions or real-world contexts, and asks you to extract information, process data and evaluate methods. That is the kind of work the subject brief describes under assessment objective AO3: analysing, evaluating and synthesising experimental procedures, data, and trends.

The upshot is that practical work done in class is direct preparation for a written exam paper. The subject brief organises chemistry skills around three tools (experimental techniques, technology and mathematics) and three inquiry stages (exploring and designing; collecting and processing data; concluding and evaluating). Paper 1B is where those skills are tested on paper.

2. Paper 1 Structure: Timings, Weightings and How 1A and 1B Fit Together

Paper 1 is a single sitting that contains two distinct papers: Paper 1A (multiple-choice questions) and Paper 1B (data-based questions and questions on experimental work). According to the IB Chemistry subject brief, that combined sitting lasts 1 hour 30 minutes at SL and 2 hours at HL, and it is worth 36% of the final grade at both levels.

Here is how the full assessment breaks down:

ComponentSL timeHL time% of final grade
Paper 1 (1A + 1B combined)1 hr 30 min2 hrs36%
Paper 2 (short answer + extended response)1 hr 30 min2 hrs 30 min44%
Scientific investigation (Internal Assessment)--20%

The external assessment, Papers 1 and 2 together, therefore accounts for 80% of the final grade, across 3 hours of total exam time at SL and 4.5 hours at HL.

One structural point worth noting: the subject brief gives a single time for Paper 1 as a whole, not separate times for 1A and 1B, so plan how you will divide those 90 or 120 minutes and follow the instructions on the paper on the day. Getting that balance wrong is a genuine time-management risk, and one that sections 4 and 5 of this guide address directly.

The practical programme sits alongside the written papers: 40 hours at SL and 60 hours at HL, covering practical work, a collaborative sciences project, and the scientific investigation. That lab time feeds directly into Paper 1B, which is where experimental reasoning is tested on paper.

3. What Does Paper 1B Actually Test?

Paper 1B sits at the practical end of IB Chemistry assessment. Where Paper 1A tests content knowledge through multiple-choice, Paper 1B tests whether you can work with data you have not seen before - graphs and tables presented fresh in the exam room, even when the experiment behind them is a familiar one.

The skills tested fall into two overlapping categories, both drawn directly from the course framework as described in the IB Chemistry subject brief:

In practice, questions built around those stages look like this:

Inquiry stageTypical question demand
Exploring and designingIdentify the independent, dependent and controlled variables; suggest how to control a variable
Collecting and processing dataRead a value from a graph; deduce a rate or trend; calculate percentage uncertainty
Concluding and evaluatingIdentify a weakness or source of error in the method; assess whether data supports a conclusion

The key point: the data in front of you will usually be new. Even when the set-up is a familiar one, such as a titration or a gas collection, you are unlikely to have seen the specific graph or table before. The exam is not testing recall of a particular practical - it is testing whether you can apply reasoning to new data. That distinction matters when you revise.

Typical tasks could include reading a value or gradient from a graph, deducing an average rate of reaction from a concentration-time graph, explaining why a described gas-collection method gives a systematic error, and calculating a percentage uncertainty from given values.

Your in-class practical work is direct preparation for all of this. The subject brief says these skills should be integrated into the teaching of the syllabus rather than taught as stand-alone topics. Paper 1B's questions on experimental work draw on the same skills. Every titration, every recorded anomaly, every uncertainty estimate you do in the lab is rehearsal for this paper.

4. How to Approach Paper 1A: IB Chemistry Multiple-Choice Strategies

Paper 1A is the multiple-choice section of Paper 1, and it shares a single time block with Paper 1B: 1 hour 30 minutes at SL and 2 hours at HL. That shared clock is easy to forget under exam conditions. Spending too long on a tricky multiple-choice item eats directly into the time you need for Paper 1B's data-based questions, which typically demand more written working.

A practical rule: treat Paper 1A as the faster half. Multiple-choice questions usually take less time each than written data questions, so if one is taking much longer than the others, flag it and move on.

A few techniques that hold up under time pressure:

On uncertain questions, narrow to two options and mark your best guess before you flag the question, so nothing is left blank if you run out of time to come back.

5. How to Approach Paper 1B: Reading Data, Processing Results and Evaluating Methods

Paper 1B is built around stimulus material: graphs, tables, experimental descriptions, and real-world contexts. The technique is less about recalling facts and more about reading carefully before writing anything.

Start with the command term

Read the command term before the data. "Describe" and "explain" are not interchangeable. Describe asks you to state what the data shows, using numbers from the graph or table. Explain asks you to link what you observe to a chemical principle, such as collision theory, equilibrium, or bond polarity. A chemical principle in a "describe" answer uses up time without adding marks, while an "explain" answer without one is unlikely to earn full credit.

Read the stimulus systematically

Before attempting an answer, identify three things in any stimulus:

A graph showing increasing product yield means something different if temperature is rising than if time is passing at constant temperature.

Processing data and showing working

When a question asks for a calculation, write every step. Unit conversion errors compound silently when working is hidden. Carry units through the calculation the same way you carry numbers.

Evaluating methods

For evaluation questions, distinguish between systematic error (consistent offset in one direction, such as a gas syringe that always reads 2 cm3 low) and random error (scatter around the true value). Identifying which type of error is present leads directly to a credible improvement. A suggested improvement that addresses random error will not fix a systematic one.

Conclude with the data

Vague qualitative answers score poorly where numbers are available in the stimulus. If the graph gives you values, quote them. A conclusion that references a specific data point is stronger than one that says only "the rate increased."

6. Using Past Papers and the IB Chemistry Data Booklet Effectively

The most important thing to understand about past papers is that May 2025 is the first sitting of the current course, which means the pool of papers matching the exact Paper 1B format is small. Papers from 2024 and earlier follow a different structure, so they cannot serve as a direct model for IB Chemistry Paper 1B questions. They are still worth working through for content knowledge and multiple-choice practice, but do not treat them as a template for what a 1B question will look like.

IB Questionbank lists DP Chemistry (last assessment 2024) and DP Chemistry (first assessment 2025) as separate subjects, so current-course questions can be kept apart from legacy ones. Access requires a licence purchased through the Follett IB Store, or a demo account for a limited question set. Official papers, mark schemes, and specimen papers are copyright-protected: if you cannot access Questionbank directly, ask your teacher, IB coordinator, or school library.

The data booklet deserves the same practice time as the questions themselves. Students who only consult it when stuck during revision end up hunting through it when the clock is running. It is provided for every paper, Paper 1A included, so use it in every timed practice until locating a specific table or equation is automatic.

One practical mindset shift: treat any past-paper data question, regardless of which syllabus it came from, as practice in reading unfamiliar stimulus material. The skill of extracting what a graph or table actually shows, before applying any chemistry, transfers across both the old and new course. That reading habit is what Paper 1B rewards.

7. Revision Strategy for Both Papers

The course is organised around two content strands, Structure and Reactivity, alongside a skills strand covering experimental techniques, technology, mathematics, and the full inquiry process. Your revision should map onto that same shape.

For Paper 1A, build active recall of definitions, equations, and periodic trends. Multiple-choice questions reward speed and confidence on material you have already processed, not material you are reading for the first time under pressure. Flashcards and spaced repetition work well for the recall side of this, but some multiple-choice items also involve calculations or reading data, so mix timed question practice in with the flashcards.

For Paper 1B, the priority shifts. Practise reading unfamiliar graphs and experimental descriptions cold, annotating them before you look at the questions. Highlight variables, units, and stated conditions. The skill being tested is whether you can extract and interpret data you have never seen, so re-reading your own class notes is not enough on its own.

One underused revision resource: your own lab write-ups and practical notes from class. Reviewing the errors and limitations you recorded in your own experimental work builds the evaluation skill that Paper 1B tests directly. The IB Chemistry subject brief builds a 40-hour (SL) or 60-hour (HL) experimental programme into the course, so lab work is part of the course itself, not an extra.

Timed practice matters. The full Paper 1 sitting is 1.5 hours at SL and 2 hours at HL, covering both 1A and 1B. Running that sitting in one go, without pausing, is different from doing sections separately. Do at least two full timed sittings before your exam.

8. What to Do Next

This week, ask your IB coordinator or teacher for a current-course Paper 1: the specimen paper or any real paper from the May 2025 session onwards. Only papers set on the current course structure are a fully reliable model for what the Paper 1B questions will look like. Papers from before 2025 can help with chemistry content, but they do not reflect the Paper 1B format.

When you get the paper, work through it under timed conditions without notes, then go back and check every answer against the mark scheme with your data booklet open. Note where you lost marks to unit errors or vague phrasing rather than a gap in knowledge. That distinction tells you exactly where to focus next.

Request the paper from your teacher or school library this week.

FAQ

What is Paper 1B in IB Chemistry?

Paper 1B is the data-based questions and experimental-work section of IB Chemistry Paper 1, sat in the same timed session as the multiple-choice Paper 1A; it draws on the tools and inquiry skills developed through the course's practical programme and was first assessed in May 2025.

How long is IB Chemistry Paper 1, and how is the time split between 1A and 1B?

Paper 1 (1A and 1B combined) lasts 1 hour 30 minutes at SL and 2 hours at HL; the subject brief gives one time for the whole paper rather than separate times for 1A and 1B, so plan your own split and follow the instructions on the paper.

How do I prepare for IB Chemistry Paper 1B?

Preparation should focus on practising with unfamiliar graphs, tables and experimental descriptions; reviewing the tools and inquiry skills strands of the course; and treating your own lab work and write-ups as revision material, since Paper 1B tests the same skills you develop throughout the practical programme.

Can I use pre-2025 IB Chemistry papers to practise for Paper 1B?

Pre-2025 papers are useful for content knowledge and multiple-choice practice, but they followed a different paper structure, so they are not a reliable model for Paper 1B questions; the IB Questionbank lists the previous course and the current course, first assessed in 2025, as separate subjects, so current-course questions can be kept apart from legacy ones.

What is the difference between 'describe' and 'explain' in IB Chemistry Paper 1B?

In Paper 1B, 'describe' asks for an account of what the data shows, ideally quoting values from the stimulus, while 'explain' asks for reasons or causes, which usually means linking those observations to a chemical principle such as collision theory, bonding, or equilibrium.

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