Explore the nitrogen oxides: unexpected equilibrium

Use a syringe of red-brown nitrogen dioxide, NO_2, gas to explore a counterintuitive example of equilibria chemistry involving dinitrogen tetroxide, N₂O₄. Explore how depressing the syringe’s plunger will cause the exothermic equilibrium to shift and cause a colour change. Ask your 14–16 and post-16 learners how the volume and temperature affect the equilibrium’s position. Then demonstrate the reaction of NO₂ with water and the neutralisation of the acid produced. Download the technician notes for health and safety information, a kit list and teaching advice from chemistry teacher, Declan Fleming.