Combustion Analysis Calculator
Determine the empirical formula of an organic compound from combustion analysis data. Enter the sample mass and the masses of CO₂ and H₂O produced to calculate the elemental composition and empirical formula.
Combustion analysis is a classical technique for determining the elemental composition of organic compounds. A known mass of the compound is burned completely in excess oxygen, and the masses of CO₂ and H₂O produced are measured.
How It Works
- All carbon in the compound is converted to CO₂. Moles of C = moles of CO₂ = mass(CO₂) / 44.01.
- All hydrogen is converted to H₂O. Moles of H = 2 × moles of H₂O = 2 × mass(H₂O) / 18.015.
- If nitrogen is present, it is collected as N₂. Moles of N = 2 × moles of N₂.
- Oxygen is determined by difference: mass(O) = sample mass − mass(C) − mass(H) − mass(N).
- The mole ratios are reduced to the simplest whole numbers to give the empirical formula.
From Empirical to Molecular Formula
The empirical formula gives the simplest ratio of atoms. To find the molecular formula, you need the actual molecular weight (from mass spectrometry or other methods). Molecular formula = n × empirical formula, where n = molecular weight / empirical formula weight.