Chemistry Regents Practice Test 2026 – The All-in-One Guide to Exam Success!

An exothermic reaction is characterized by the release of heat energy into the surroundings. During this type of reaction, the total energy of the products is lower than that of the reactants, resulting in the difference being released as thermal energy. This can lead to an increase in the temperature of the surrounding environment.

For example, combustion reactions, such as burning fuels like propane or natural gas, are classic exothermic reactions that release heat energy, which can be utilized for cooking or heating. The heat released can often be felt, which is a tangible indicator that an exothermic process is taking place.

The other characteristics mentioned in the incorrect options do not accurately describe exothermic reactions. While some reactions may require a catalyst, exothermic reactions do not inherently require one—they can occur spontaneously. Additionally, exothermic reactions can involve various types of reactants, not just solids, as they can also occur with gases and liquids.