Chapter 5, Problem 129AE

The nitrogen content of organic compounds can be determined by the Dumas method. The compound in question is first reacted by passage over hot CuO(s):

$\text{Compound }\underset{\text{CuO(}s\text{)}}{\overset{\text{Hot}}{\to }}{\text{ N}}_{\text{2}}\left(g\right)+{\text{ CO}}_{\text{2}}\left(g\right)+{\text{ H}}_{\text{2}}\text{O}\left(g\right)$

The product gas is then passed through a concentrated solution of KOH to remove the CO₂. After passage through the KOH solution, the gas contains N₂ and is saturated with water vapor. In a given experiment a 0.253-g sample of a compound produced 31.8 mL N₂ saturated with water vapor at 25°C and 726 torr. What is the mass percent of nitrogen in the compound? (The vapor pressure of water at 25°C is 23.8 torr.)