Final answer:
Heating iron sulfate changes its chemical classification, as demonstrated by the synthesis reaction forming a different product. In hand warmers, the air-oxidation of iron is temperature-dependent for its spontaneity, which involves Gibbs free energy calculations.
Step-by-step explanation:
When you heat iron sulfate, does it change classification? Yes, heating iron sulfate can lead to a chemical reaction that changes its classification. For instance, the reaction described in which a mixture glows bright red and produces a dark-colored product called iron sulfide is an example of a synthesis reaction. In this process, the iron sulfate reacts to form an entirely new product with different properties, indicating a change in its chemical classification.
Regarding the chemical hand warmers that generate heat through the air-oxidation of iron, the spontaneity of the reaction 4Fe(s) + 3O₂(g) → 2Fe₂O₃(s) is dependent on temperature. Generally, increased temperature may increase reaction rates, but for spontaneity, we have to consider Gibbs free energy. A spontaneous reaction has a negative Gibbs free energy, which incorporates both enthalpy and entropy changes of the reaction influenced by temperature.