In which scenario is thermal decomposition typically classified?

Thermal decomposition is classified as an endothermic reaction. In this process, a compound breaks down into simpler substances when heated, absorbing heat from the surroundings. This absorption of heat indicates that thermal decomposition requires energy input, which defines it as endothermic.

For instance, when calcium carbonate (CaCO3) is heated, it decomposes into calcium oxide (CaO) and carbon dioxide (CO2). The reaction absorbs heat to facilitate this breakdown, demonstrating the characteristics of an endothermic reaction.

This sets it apart from exothermic reactions, which release energy, and from non-reversible reactions because thermal decomposition can be reversed under certain conditions. Additionally, while catalysts may be involved in some thermal decomposition processes, they do not define the classification; the primary characteristic remains the requirement of heat, affirming the endothermic nature.