Combustion stoichiometry check: One kilogram of sulphur (S) reacts with one kilogram of oxygen (O2) to yield two kilograms of sulphur dioxide (SO2). Is this statement correct?
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ATrue
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BFalse
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CTrue only with excess air
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DTrue only at high pressure
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EFalse, product is SO3 instead
Answer
Correct Answer: True
Explanation
Introduction / Context:Sulphur oxidation is a standard stoichiometric reaction in combustion and gas treatment. Verifying mass ratios builds comfort with balancing reactions and predicting flue-gas composition for desulphurization or sulfuric acid production trains.
Given Data / Assumptions:
- Reaction considered: S + O2 → SO2 (complete oxidation to dioxide).
- Atomic masses: S = 32, O = 16.
- Ideal, complete conversion without side reactions.
Concept / Approach:
Balance by moles: 1 mol S (32 kg/kmol) reacts with 1 mol O2 (32 kg/kmol) to form 1 mol SO2 (64 kg/kmol). Thus, per kilogram basis, 1 kg S needs 1 kg O2 and produces 2 kg SO2. While further oxidation to SO3 can occur in catalytic processes, the primary combustion product without catalyst is SO2.
Step-by-Step Solution:
Write reaction: S + O2 → SO2.Compute masses: 32 + 32 → 64 (kg per kmol basis).Scale per kg: 1 kg S + 1 kg O2 → 2 kg SO2.Verification / Alternative check:
Mass conservation and standard oxidation supports the same ratio; flue-gas analyzers report SO2 as the primary sulfur oxide absent catalytic conversion.
Why Other Options Are Wrong:
Dependence on excess air or pressure does not change the stoichiometric mass ratio for the ideal reaction.SO3 formation requires specific catalytic conditions; it is not the default product in simple combustion.
Common Pitfalls:
Confusing oxygen atom mass with O2 molecular mass; always use O2 = 32 for combustion stoichiometry.
Final Answer:
True