Using PV = nRT, we can calculate the moles of the sample. 874 mmHg = 116,524 Pa n = PV/RT n = 116,524 x 294 x 10⁻⁶ / 8.314 x (140 + 273) n = 9.98 x 10⁻³ mol
moles = mass / Mr Mr = 0.271/9.98 x 10⁻³ Mr = 27.2 Mass of empirical formula = 14 Repeat units = 27.2 / 14 ≈ 2
Formula of substance: C₂H₄
Combustion equation: C₂H₄ + 3O₂ → 2CO₂ + 2H₂O
1 mole produces 2 moles of CO₂, so 3 moles will produce 6 moles CO₂
