IB Chemistry: Green Chemistry & Sustainability FAQ

It's tested as an applied concept, not a discrete topic — examiners embed the twelve principles of green chemistry into questions on reaction pathways, atom economy, solvents and energy sources across both papers. According to the IB Chemistry guide (first exams 2025), sustainability is a 'nature of science' thread running through structural, reactivity and energy topics.

Green chemistry, in IB terms, means designing chemical processes that minimise waste, use safer solvents, and reduce energy demand — measured through concepts like atom economy, percentage yield and E-factor. It appears explicitly under reaction pathways (structure 3) and energy (reactivity 3) in the current DP Chemistry guide.

Three areas carry most of the weight: reactivity 3.4 (energy changes and fuel choice), structure 3.1–3.2 (industrial synthesis routes, including the Haber and Contact processes), and any option-linked practical work on catalysis. Atom economy and percentage yield calculations recur in reactivity 1 as well.

Both, but differently. Paper 1 (multiple choice) tests recall — atom economy formulas, catalyst function, energy source comparisons. Paper 2 (structured, extended response) is where green chemistry really bites, asking you to evaluate a process or compare two synthesis routes using sustainability criteria worth 3–6 marks.

Give a balanced judgement, not a list. State one advantage and one disadvantage of the process against a named green chemistry criterion — atom economy, toxicity, energy use — then reach a conclusion. Examiners reward the reasoning chain, not just naming the criterion.

Writing 'it's more sustainable because it's greener' with no named criterion. That earns zero marks. I've marked hundreds of scripts where the chemistry was fine but the answer never touched atom economy, energy input, or waste — the actual assessable content the mark scheme wants.

You'll be given a balanced equation and asked to calculate atom economy as a percentage, then use that figure to compare two routes to the same product. The formula is mass of desired product divided by total mass of reactants, times 100.

Yes, and it's a strong choice if you keep it genuinely investigative rather than descriptive. Good angles include comparing reaction rates or yields under different solvent conditions, or measuring atom economy across alternative synthesis routes you actually perform in the lab.

It can work well, provided you narrow it to a specific, testable research question — for example, comparing catalytic efficiency of two green catalysts in a named reaction — rather than a broad survey of sustainability in industry, which tends to score poorly on the analysis criterion.

Not conceptually hard, but easy to underperform on because it's assessed through application, not recall. Students who've memorised definitions often freeze when asked to evaluate an unfamiliar industrial process — the fix is practising past-paper 'evaluate' and 'discuss' questions specifically on synthesis routes and energy sources.

Both levels cover the same core concepts, but HL questions typically ask you to weigh two or three green chemistry criteria simultaneously for higher mark allocations, while SL questions tend to test a single criterion in isolation with shorter response space.

The current DP Chemistry guide, first examined in 2025, builds sustainability and green chemistry into its 'nature of science' strand deliberately, reflecting how industry now designs chemical processes. It's not extra content bolted on — it's how the whole course frames reactivity and synthesis.

Look for resources built around applying concepts to unfamiliar synthesis routes, not just definitions — past-paper style questions with mark schemes are far more useful here than glossaries. RevisionPrep's Chemistry Revision Notes and Topical Worksheets group these questions by command term so your child practises the actual skill being examined.