When a chemical change occurs, the event is usually accompanied by __________.

When a chemical change occurs, it typically involves the transformation of substances into different chemical entities, which is often accompanied by the release of energy. This release can take the form of heat (exothermic reactions), light, or sound. Such energy changes are fundamental indicators of a chemical reaction taking place, as they reflect the making and breaking of chemical bonds.

While absorption of heat can also occur during some chemical changes (as in endothermic reactions), the overall characteristic of a chemical change includes a visible release of energy in many common reactions. Change in state pertains more to physical changes rather than chemical transformations, while "no observable change" does not accurately describe the typical nature of a chemical change, which is generally marked by observable signs, such as color change, gas production, or precipitate formation. Thus, the release of energy serves as a key indicator of the chemical change process.