Who this is for: Cambridge IGCSE Coordinated Science (0654) students who want sulfur — its extraction, combustion to sulfur dioxide and link to acid rain — to become reliable marks instead of disconnected facts about yellow powder and pollution.
What query it owns: how to understand and revise sulfur in Cambridge IGCSE Coordinated Science.
Why this is safe: this page owns the sulfur revision-guide angle, while Tutopiya’s Sulfur subtopic page owns the learning resource and the free Sulfur quiz owns the practice.

Sulfur is an important non-metal in Cambridge IGCSE Coordinated Science (0654). Examiners expect you to describe how sulfur is extracted, what happens when it burns to form sulfur dioxide (SO₂), and how SO₂ contributes to acid rain. Sulfur compounds also have major industrial uses — especially in making sulfuric acid. This guide covers the syllabus definitions, reaction equations examiners reward, and the question types that appear every year.

Key takeaways

• Sulfur is extracted from underground Frasch process deposits or recovered from volcanic and fossil fuel sources.
• Sulfur burns in oxygen to form sulfur dioxide: S + O₂ → SO₂.
• Sulfur dioxide dissolves in rainwater to form sulfurous acid, contributing to acid rain.
• Acid rain damages buildings (limestone, marble), lakes (kills fish) and plant leaves.
• Sulfur is used to manufacture sulfuric acid (H₂SO₄), the most widely used industrial chemical.

What is sulfur in Cambridge IGCSE Coordinated Science?

Sulfur is a yellow, brittle non-metal found in elemental form underground and in metal sulfide ores. When burned, it produces sulfur dioxide — a pollutant from burning fossil fuels containing sulfur impurities. SO₂ reacts with oxygen and water in the atmosphere to form sulfuric acid, lowering the pH of rain. The syllabus also links sulfur to the Contact process for making sulfuric acid.

Read the full notes on Tutopiya’s Sulfur subtopic page before attempting questions.

The core ideas you must master

Idea	What it means	How the exam uses it
Extraction	Frasch process from underground deposits	”Describe how sulfur is obtained.”
Combustion	S + O₂ → SO₂	”Write the equation for burning sulfur.”
Acid rain	SO₂ + H₂O → acid in rain	”Explain how sulfur dioxide causes acid rain.”
Environmental effects	Damaged buildings, lakes, vegetation	”Describe an effect of acid rain.”
Industrial use	Sulfuric acid manufacture	”State a use of sulfur.”

Sulfur dioxide and acid rain — step by step

1. Sulfur impurities in coal and oil burn to form SO₂.
2. SO₂ rises into the atmosphere and dissolves in cloud water.
3. Further oxidation produces sulfuric acid (H₂SO₄) in rainwater.
4. Acid rain (pH below 5.6) falls on buildings, lakes and forests.
5. Effects: limestone/marble erodes; lake pH falls → fish die; leaf damage on trees.

Uses of sulfur and its compounds

Compound / process	Use	Why sulfur is needed
Sulfuric acid (H₂SO₄)	Fertilisers, batteries, detergents	Most important industrial acid
Contact process	Manufacture of H₂SO₄ from SO₂	Links combustion to industry
Vulcanisation of rubber	Harden rubber tyres	Sulfur cross-links polymer chains
Fungicides	Crop protection	Sulfur compounds kill fungi

Sulfur in past-paper wording

Command word	What the question wants	Typical stem
Write / State equation	S + O₂ → SO₂	”Write the equation for burning sulfur.”
Explain	Cause and effect chain	”Explain how burning coal causes acid rain.”
Describe	Effect on environment	”Describe an effect of acid rain on lakes.”
State	Use or source	”State a use of sulfur.”
Suggest	Reduction measure	”Suggest how to reduce sulfur dioxide emissions.”

Worked exam-style stems

1. “Write a word equation for the burning of sulfur in oxygen.” Sulfur + oxygen → sulfur dioxide. Reward: correct reactants and product.
2. “Explain how sulfur dioxide in the atmosphere causes acid rain.” SO₂ dissolves in rainwater and reacts to form sulfuric acid; rain with pH below normal falls on the ground. Reward: SO₂ + water → acid + named effect.
3. “Describe one effect of acid rain on the environment.” Acid rain lowers pH of lakes, killing fish and aquatic organisms / damages limestone buildings / damages tree leaves. Reward: specific, syllabus-linked effect.

Practise on the Sulfur quiz.

How sulfur connects to the syllabus

Sulfur links to Air (atmospheric pollution) and Human Influences on Ecosystems (acid rain damage). The Cambridge IGCSE Coordinated Science resource hub links every Chemistry subtopic.

Common mistakes students make

• Writing SO₃ as the direct product of burning sulfur (first product is SO₂).
• Confusing acid rain causes — SO₂ from sulfur vs NOₓ from vehicle engines.
• Saying acid rain kills all plants (some tolerate it; examiners want specific effects).
• Forgetting sulfur is found in fossil fuels as an impurity, not just volcanic sources.
• Missing the link between SO₂ and sulfuric acid manufacture.

When you need more support

If sulfur and acid-rain questions keep costing marks, work through the Sulfur quiz, then get help from a Cambridge IGCSE Coordinated Science tutor.

Frequently asked questions

What is formed when sulfur burns in oxygen? Sulfur dioxide (SO₂).

How does sulfur dioxide cause acid rain? SO₂ dissolves in rainwater and is oxidised to form sulfuric acid, lowering the pH of rain.

What is sulfur used for? Mainly to manufacture sulfuric acid, and in vulcanisation of rubber and fungicides.

How do I revise sulfur effectively? Learn the combustion equation, acid-rain steps, environmental effects and industrial uses, then take the quiz.

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