When an organic compound containing Carbon, Hydrogen, and Nitrogen undergoes complete combustion wit — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Complete combustion with $CuO$ oxidizes carbon to $CO_2$ and hydrogen to $H_2O$ vapor. The nitrogen in the compound is mostly liberated as free $N_2$ gas. However, a fraction of the nitrogen may be oxidized to various oxides of nitrogen. All these gases pass down the tube. The subsequent heated copper gauze is specifically needed to reduce these oxides of nitrogen back to $N_2$.