The analysis which is made to determine the amounts of different elements present in a compound by burning a known amount of organic compound containing C, H and O in the presence of oxygen is called” combustion analysis.”
A weighed sample of the organic compound is placed in the combustion tube. This combustion tube is fitted in a furnace. Oxygen is supplied to bum the organic compound. Hydrogen is converted into H20 and carbon into CO2.
Next to combustion tube is H20 absorber. It contains Mg (ClO4) which absorbs H2O produced during the burning of organic compound.
After H2O absorber chamber is CO2 absorber chamber. It contains 50% of KOH which absorbs CO2 produced during combustion analysis. The difference in the amounts or masses of these absorbers gives us the amounts of H2O and CO2
% of carbon = [mass of CO2 mass ÷ mass of organic compound] X [12/44] X 100
% of hydrogen = [mass of H2O ÷ mass of organic compound] X [2.016/18] X 100
The percentage of oxygen is obtained byjthe method of difference:
% of Oxygen = 100 – (% of carbon + % of hydrogen)