Thermite reaction. Time-exposure image of sparks caused by a thermite reaction as an aluminium wrench strikes a block of rusty iron (iron oxide). Aluminium (Al) is more reactive than iron (Fe) and can remove oxygen (O) from it. The heat needed to begin the reaction is provided here by friction between the wrench and block. The equation for the reaction is: 2Al + Fe2O3 ----> Al2O3 + 2Fe The heat and sparks generated by a thermite greaction can be a fire hazard. Photographed during research conducted by the Health and Safety Laboratory in Britain.