Stoichiometry of Carbon Combustion – Mass Ratios for Complete Oxidation One kilogram of carbon requires 8/3 kg of oxygen for complete combustion and produces 11/3 kg of carbon dioxide: C + O2 → CO2.

Introduction / Context:
Accurate stoichiometric ratios are essential for combustion calculations, flue-gas analysis, and sizing of air-fuel systems. The carbon–oxygen reaction to form carbon dioxide is a fundamental example.

Given Data / Assumptions:

• Chemical reaction: C + O2 → CO2 (complete combustion, no CO formation).
• Molar masses: M_C = 12 kg/kmol, M_O2 = 32 kg/kmol, M_CO2 = 44 kg/kmol.
• Idealized, complete oxidation with no side reactions.

Concept / Approach:

Mass conservation across the balanced equation yields fixed mass ratios. For each 12 kg of C, 32 kg of O2 are required, and 44 kg of CO2 are produced. Scaling to 1 kg of C gives oxygen requirement 32/12 = 8/3 kg and CO2 produced 44/12 = 11/3 kg.

Step-by-Step Solution:

Verification / Alternative check:

Elemental balance on C and O confirms stoichiometry. Flue-gas analyzers would measure CO2 consistent with these ratios under ideal complete combustion.

Why Other Options Are Wrong:

Pressure, oxygen purity, or air humidity do not change the stoichiometric mass ratios; they affect kinetics or dilution, not the balanced-equation proportions.

Common Pitfalls:

Confusing air requirement with oxygen requirement; neglecting possible CO formation under oxygen-deficient conditions (not considered here).

Final Answer:

Agree