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.