MYP Chemistry: Combustion & Fuels FAQ

Combustion is an exothermic reaction between a fuel and oxygen that releases energy as heat and light. In MYP Chemistry you study hydrocarbon fuels — methane, propane, petrol — reacting with oxygen to form carbon dioxide and water, plus the energy changes and particle-level explanations Criterion A questions usually test.

Complete combustion happens with plenty of oxygen and produces only carbon dioxide and water, releasing the maximum available energy. Incomplete combustion occurs when oxygen is limited and produces carbon monoxide, carbon (soot) and water instead — releasing less energy and creating a colourless, poisonous gas examiners love to ask about.

Fossil fuels — coal, oil and natural gas — formed over millions of years from decayed plant and animal matter under heat and pressure underground. They're used because they're energy-dense, easy to transport and the world's existing infrastructure runs on them, though burning them releases carbon dioxide, which your Criterion D answers should link to climate change.

Combustion is always exothermic — it releases more energy than it takes in, so the surroundings warm up and heat (often light too) is given off. An endothermic reaction absorbs energy from its surroundings and gets colder instead. You will never find combustion classified as endothermic on an MYP mark scheme.

Combustion & fuels is assessed like every MYP Sciences unit — through the four IB criteria, not a single test. Criterion A checks your factual understanding of combustion reactions; Criterion B assesses a practical investigation you design (often calorimetry); Criterion C evaluates your data processing; Criterion D judges your discussion of environmental impacts.

A top-band Criterion B/C investigation needs a focused, testable research question (e.g. 'How does fuel type affect the temperature rise of 100ml of water?'), a controlled-variables table, repeated trials, and a discussion of accuracy that names specific limitations. Examiners reward precise, chemistry-linked improvements — not vague lines like 'do more trials.'

Combustion questions use the same MYP command terms as the rest of Sciences: 'state' wants a fact with no explanation; 'explain' wants reasons or causes linked with because/therefore; 'evaluate' wants strengths and weaknesses weighed against each other; 'discuss' wants a balanced argument covering more than one viewpoint on fuel choice or impact.

In MYP 4-5 the unit typically covers the combustion word and symbol equation, complete vs incomplete combustion, fuel types (fossil, biofuels, hydrogen), energy changes and calorimetry, and the environmental consequences of burning fuels including greenhouse gases and acid rain. Schools sequence this differently, since the MYP framework lets teachers design their own units.

Burning fossil fuels releases carbon dioxide, a greenhouse gas that traps heat in the atmosphere and drives global warming — this is the direct chain of reasoning Criterion D questions expect, not just a mention of 'pollution.' The IB's MYP framework builds this unit around the global context of Globalisation and Sustainability, one of its six official contexts.

Yes — students sitting the optional MYP eAssessment in Year 5 can be examined on combustion & fuels within the on-screen Sciences paper, which draws on Criteria A and C using unfamiliar data and short-answer questions. Most schools, however, assess this unit through internal coursework and investigations rather than the eAssessment alone.

MYP combustion & fuels lays the groundwork for DP Chemistry's energetics topic, where you calculate enthalpy changes (ΔH) using Hess's Law and bond enthalpies. The MYP unit is conceptual and investigative; DP demands quantitative, exam-style calculations done under time pressure with a specific mark scheme.

There's no single 'better' fuel — each carries a trade-off examiners want you to weigh. Fossil fuels are energy-dense but non-renewable and carbon-heavy; biofuels are renewable but compete with food crops for land; hydrogen burns cleanly, producing only water, but is expensive and tricky to store safely. A strong answer compares at least two directly.

The most effective revision mixes recall with application: your child should be able to write and balance combustion equations from memory, then apply that knowledge to unfamiliar data-based questions — exactly how MYP Criterion A and C are assessed. Past investigation write-ups matter more here than re-reading notes.

Look for resources that mirror the MYP criteria directly rather than generic chemistry notes — practice questions that require designing an investigation (Criterion B) or evaluating environmental impact (Criterion D), not just equation drills. Topical worksheets built around these exact command terms make revision far more targeted than rereading a textbook.