Question

Thermite" reactions have been used for welding metal parts such as railway rails and in metal refining. One such thermite reaction is: Fe₂O₃(s)+2Al(s)⟶Al₂O₃(s)+2Fe(s) Fe₂O₃(s)+2Al(s)⟶Al₂O₃(s)+2Fe(s) Is the reaction spontaneous at room temperature under standard conditions? During the reaction, the surroundings absorb 851.8 kJ/mol of heat.

Answer 1

The thermite reaction between aluminum powder and iron(III) oxide is highly exothermic and is used to weld metal parts, releasing 850.2 kJ/mole of energy. Spontaneity of the reaction at room temperature cannot be confirmed without entropy values, despite its exothermic nature.

Step-by-step explanation:

The thermite reaction involving aluminum metal powder and iron(III) oxide is a highly exothermic reaction, meaning it releases a significant amount of heat.

The balanced equation for this reaction is: 2 Al(s) + Fe₂O₃(s) → 2 Fe(s) + Al₂O₃(s). During the process, the system releases heat to the surroundings, as indicated by the negative enthalpy change (ΔH) of -850.2 kJ. This release of heat is sufficient to melt the iron, which can then be used to weld metal parts, such as railway rails.

If we look at the spontaneity of the reaction under standard conditions at room temperature, we need to consider both the enthalpy change (ΔH) and the change in entropy (ΔS) to determine the reaction's Gibbs free energy change (ΔG).

Although the question does not provide entropy values, the fact that the reaction is highly exothermic and generates a more ordered system (going from aluminum powder and iron oxide to solid iron and aluminum oxide) suggests that the reaction might be spontaneous because most exothermic reactions with increasing order tend to be favorable.

However, without the entropy data, we can't conclusively determine the spontaneity just based on the enthalpy change alone.