What mass of carbon dioxide is produced from the complete combustion of 4.80×10−3 g of methane?

Molar mass of CH₄ = (12.0 + 1.0×4) g/mol = 16.0 g/mol
Molar mass of O₂ = 16.0×2 g/mol = 32.0 g/mol
Molar mass of CO₂ = (12.0 + 16.0×2) g/mol = 44.0 g/mol


b)
CH₄ + 2O₂ → CO₂ + 2H₂O
Combustion of 1 mole of CH₄ (methane) gives 1 mole of CO₂ (carbon dioxide)

No. of moles of CH₄ burned = (4.80 × 10⁻³ g) / (16.0 g/mol) = 3.00 × 10⁻⁴ mol
No. of moles of CO₂ produced = 3.00 × 10⁻⁴ mol
Mass of CO₂ produced = (3.00 × 10⁻⁴ mol) × (44.0 g/mol) = 1.32 × 10⁻² g


c)
CH₄ + 2O₂ → CO₂ + 2H₂O
Combustion of 1 mole of CH₄ (methane) needs 2 moles of O₂ (oxygen)

No. of moles of CH₄ burned = (4.80 × 10⁻³ g) / (16.0 g/mol) = 3.00 × 10⁻⁴ mol
No. of moles of O₂ needed = (3.00 × 10⁻⁴ mol) × 2 = 6.00 × 10⁻⁴ mol
Mass of O₂ needed = (6.00 × 10⁻⁴ mol) × (32.0 g/mol) = 1.92 × 10⁻² g