Question

In Dumas method for the estimation of nitrogen in anorganic compound, nitrogen is determined in the form of :

• A. Gaseous nitrogen
• B. Sodium cyanide
• C. Ammonium sulphate
• D. Gaseous ammonia

Answer 1

The correct option is A Gaseous nitrogen

Dumas' method
A known mass of the organic compound is heated with cupric oxide in an atmosphere of carbon dioxide. The carbon and hydrogen in the compound are oxidised to carbon dioxide and water respectively, while nitrogen is set free. Any oxide of nitrogen produced during this process, is reduced back to free nitrogen by heated copper gauze. The gaseous mixture consisting of $C{O}_2,H_{2}O$ and $N_2$ is collected over an aqueous solution of potassium hydroxide. All the gases except nitrogen are absorbed by the solution. The volume of gas (nitrogen) collected is measured. From the volume of nitrogen obtained the percentage of nitrogen in the compound is calculated.