What gas is produced when nitrate ions are treated with sodium hydroxide, aluminum foil and warm?

• A. Ammonia produced.
• B. Hydrogen produced.
• C. Oxygen produced.
• D. Nitrogen gas produced.

Answer: (A)

This question hinges on redox chemistry in strongly basic, heated conditions with aluminum as the reducing agent. When nitrate ions are treated with hot sodium hydroxide in the presence of aluminum foil, the aluminum donates electrons and reduces the nitrate to ammonia. The alkaline medium, created by the sodium hydroxide, helps drive this reduction and supplies the hydroxide environment that stabilizes the reaction, while water provides hydrogen to form NH3. The heat speeds the reaction, making it observable as a gas release. So the gas produced is ammonia.