The Dumas method is a technique used to estimate the amount of nitrogen present in an organic compound. This method involves the combustion of the organic compound in a combustion tube containing copper oxide, which converts the carbon and hydrogen in the compound into carbon dioxide and water vapour, respectively. The nitrogen in the compound is converted into nitrogen gas, which is collected and measured.


- Amount of organic compound = 0.35 g
- Volume of nitrogen collected = 55 mL
- Temperature = 300 K
- Pressure = 715 mm
- Aqueous tension at 300 K = 15 mm


The volume of nitrogen collected needs to be corrected to standard temperature and pressure (STP) conditions before calculating the percentage composition of nitrogen in the compound.

Using the following formula, the volume of nitrogen at STP can be calculated:
V1/T1 = V2/T2

Where,
V1 = volume of nitrogen collected at 300 K and 715 mm pressure
T1 = temperature at which nitrogen was collected (300 K)
V2 = volume of nitrogen at STP
T2 = STP temperature (273 K)

Substituting the values in the above formula, we get:
V2 = V1 x (T2/T1) x (P1/P2)
V2 = 55 mL x (273 K/300 K) x (715 mm/760 mm)
V2 = 50.39 mL

Now, using the Dumas method formula, the percentage composition of nitrogen in the compound can be calculated:
% Nitrogen = (V2 x 22.4 L/mol) / weight of compound

Where,
V2 = volume of nitrogen at STP (in mL)
22.4 L/mol = volume of 1 mole of gas at STP
Weight of compound = 0.35 g

Substituting the values in the above formula, we get:
% Nitrogen = (50.39 x 22.4) / 0.35
% Nitrogen = 321.62

Therefore, the percentage composition of nitrogen in the compound is 32.16%.


The Dumas method is based on the principle that when an organic compound is burned in a combustion tube, the carbon and hydrogen in the compound react with copper oxide to form carbon dioxide and water vapour, respectively. The nitrogen in the compound is converted into nitrogen gas, which is collected and measured. The volume of nitrogen collected is then corrected to STP conditions and the percentage composition of nitrogen in the compound is calculated using the formula mentioned above. The aqueous tension at 300 K is taken into account while calculating the volume of nitrogen at STP.

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