How do you make NO2 in the lab?

Nitrogen dioxide (NO2) can be produced in the lab by reacting copper (Cu) with concentrated nitric acid (HNO3). The reaction can be represented as: 3 Cu + 8 HNO3 → 3 Cu(NO3)2 + 2 NO + 4 H2O. Upon heating, the nitrogen monoxide (NO) generated can further oxidize in the presence of oxygen to form NO2. It’s important to conduct this process in a well-ventilated area or a fume hood due to the toxic nature of nitrogen dioxide.