Exam technique · Chemistry · 3 min read
IB Chemistry exams now: Paper 1A, 1B and 2 (2025 syllabus)
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IB Chemistry was rebuilt for exams from May 2025. The options are gone, the course is organised into two strands (Structure and Reactivity), and there are now only two exam papers. One change catches a lot of students out: calculators are now allowed in Paper 1A, the multiple-choice section, and you have the data booklet there too. On the old course, Paper 1 was calculator-free.
The papers
| Item | SL | HL |
|---|---|---|
| Paper 1 (1A + 1B, one sitting) | 1 h 30 min · 55 marks · 36% | 2 h · 75 marks · 36% |
| Paper 1A | 30 multiple-choice questions (30 marks) | 40 multiple-choice questions (40 marks) |
| Paper 1B | Data-analysis questions linked to practical work (25 marks) | Data-analysis questions linked to practical work (35 marks) |
| Paper 2 | 1 h 30 min · 50 marks · 44% | 2 h 30 min · 90 marks · 44% |
| Internal assessment | 20% | 20% |
All of these figures are from the IB Chemistry guide (first assessment 2025). Calculators are allowed in Paper 1A, Paper 1B and Paper 2, and every candidate must have a clean copy of the Chemistry data booklet in both papers. Note that HL Paper 2 is worth 90 marks, not the 80 of Biology HL.
What that means for your preparation
Practise MCQs with a calculator in hand. Paper 1A questions can now include calculations. Old calculator-free MCQs are still good practice, but they don't prepare you for the time pressure of calculating within a multiple-choice paper. My Paper 1A guide covers how to pace that.
Know your data booklet. You'll have it in every paper. Know where the constants, equations and tables are so you're not hunting for them under time pressure. Practise with the same booklet you'll get in the exam.
Paper 1B is about experimental data. Expect results, graphs and uncertainties from practical work: identifying variables, processing data, propagating uncertainty and drawing conclusions. The IA skills and the 1B skills are the same skills.
Paper 2 is all compulsory on HL (per the specimen paper). There's no choosing your favourite question, so gaps anywhere in the syllabus cost marks.
Habits that save marks in Chemistry
These come up with my students again and again:
- Units and significant figures. Carry units through every line of a calculation. Keep full precision in the calculator and only round the final answer.
- Plug back. After solving for something, put it back into the original equation. It takes ten seconds and catches a surprising number of errors.
- Write the equation first. For stoichiometry, a balanced equation before any numbers. Most mole errors start with a skipped or unbalanced equation.
- Command terms. "State" a value means no working needed, "calculate" means show working. See IB command terms.
Using older past papers
Pre-2025 papers are still useful for most content, but check that each topic is still on the syllabus, and remember that old Paper 1 was calculator-free and old Paper 3 covered options that no longer exist. The data-based section of old Paper 3 is the closest match to the new Paper 1B.
The internal assessment
The same "scientific investigation" format as Biology and Physics: an individual report of up to 3,000 words, with half of the marks for the conclusion and evaluation. You can work in groups of up to three if each student has their own research question and data and writes their own report. See the research question guide, and for what each of the four criteria rewards, the science IA criteria guide.
Practice
Heptavo covers the current Chemistry syllabus at SL and HL, Structure and Reactivity, with calculations worked step by step the way a mark scheme awards them.
Sources
- IB: Chemistry curriculum updates (two papers, options removed, IA up to 3,000 words, 50% of IA marks for conclusion and evaluation).
- IB Chemistry guide, first assessment 2025 (papers, timings, marks, weightings, calculator and data-booklet rules).