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Question
Differentiate between the principle of estimation of nitrogen in an organic compound by Dumas method.
Solution
In Dumas method, a known quantity of nitrogen containing organic compound is heated strongly with excess of copper oxide in an atmosphere of carbon dioxide to produce free nitrogen in addition to carbon dioxide and water. The chemical equation involved in the process can be represented as
\[\ce{CxHyNz + (2x + y/2) CuO -> xCO_2 + y/2H_2O + z/2N_2 + (2x + y/2)Cu}\]
The traces of nitrogen oxides can also be produced in the reaction, which can be reduced to dinitrogen by passing the gaseous mixture over a heated copper gauge. The dinitrogen produced is collected over an aqueous solution of potassium hydroxide. The volume of nitrogen produced is then measured at room temperature and atmospheric pressure
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| (iii) Carius method | (c) Nitrogen gas |
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\[\ce{C2H7N + (2x + \frac{y}{2}) CuO -> xCO2 + \frac{y}{2} H2O + \frac{z}{2} N2 + (2x + \frac{y}{2}) Cu}\]
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