What is combustion analysis?
Combustion analysis is a powerful technique for determining the simplest (or empirical) formula of a compound. A simplest formula is the lowest whole number ratio of elements that can represent the composition of a compound. The molecular formula of a compound is the whole number ratio of atoms that are actually present in a molecule. Sometimes the simplest formula is the same as the molecular formula; sometimes it is not. Consider the following two cases. Sucrose has a molecular formula C12H22O11. This is also its simplest formula. Glucose has a molecular formula C6H12O6. However, its simplest formula is CH2O because this is the lowest whole number ratio that can represent the ratio of atoms found in this molecule. In combustion analysis, a known mass of a compound (with an unknown formula but known elemental makeup) is burned in an excess of oxygen gas. The carbon and hydrogen present in the compounds are converted into carbon dioxide (CO2) and water (H2O) respectively. The masses of
