Final answer:
To perform the thermite reaction for welding railway tracks, aluminum metal powder and iron(III) oxide are used, which react exothermically to produce molten iron and aluminum oxide.
Step-by-step explanation:
The thermite reaction used for welding broken railway tracks involves the reaction of aluminum metal powder with iron(III) oxide (Fe₂O₃). This reaction is highly exothermic and is written as follows:
2 Al(s) + Fe₂O₃(s) → 2 Fe(s) + Al₂O₃(s)
During the reaction, the aluminum reduces the iron oxide to molten iron, while itself oxidizing to aluminum oxide (Al₂O₃). The intense heat from the reaction melts the iron, which can then be used to fill the space between broken railway tracks, quickly cooling to form a solid and durable weld.
Reactants like iron(II) chloride or copper(II) sulfate are not used in the classic thermite reaction for welding purposes.