Chemistry Regents Practice Test 2025 – Complete Prep Resource

The primary distinction between exothermic and endothermic reactions lies in the transfer of energy in the form of heat during the reactions. In exothermic reactions, energy is released into the surroundings as heat. This is typically observed in processes such as combustion, where substances like fuels react to produce heat and light, resulting in an increase in the temperature of the environment.

Conversely, endothermic reactions absorb energy from the surroundings, which usually causes a decrease in the temperature of the environment. This can be seen in processes like photosynthesis, where plants absorb sunlight to convert carbon dioxide and water into glucose and oxygen.

Understanding this distinction is essential in grasping the concepts of thermodynamics in chemistry. The specific characteristics related to phases (gas, solid, etc.) or energy input requirements are not accurate representations of the fundamental differences between these two types of reactions. Thus, the correct answer provides a clear and concise overview of how each type of reaction interacts with energy, which is crucial for chemistry students.