(nh4)2cr2o7-n2-mg3n2-nh4cl
(NH₄)₂Cr₂O₇ (t°C)= N₂ + Cr₂O₃ + 4H₂O N₂ + 3Mg (t°C)= Mg₃N₂ Mg₃N₂ + 8HCl = 3MgCl₂ + 2NH₄Cl