Exothermic

Definition

An exothermic process is a chemical reaction or physical change that releases energy in the form of heat. This means that the products of the reaction have less energy than the reactants, and the excess energy is released as heat to the surrounding environment.

5 Must Know Facts For Your Next Test

1. In an exothermic reaction, the products have less energy than the reactants, so the excess energy is released as heat to the surroundings.
2. Exothermic reactions are often accompanied by an increase in temperature of the system and a decrease in the temperature of the surroundings.
3. Exothermic reactions are commonly used in everyday life, such as in the burning of fuels, the cooking of food, and the production of hand warmers.
4. The amount of heat released during an exothermic reaction is measured by the change in enthalpy, denoted as ΔH, which is always negative for exothermic reactions.
5. Exothermic reactions are often preferred in industrial and chemical processes because the released heat can be used to drive other processes or generate electricity.

Review Questions

• Explain how an exothermic reaction differs from an endothermic reaction in terms of energy changes.
  • In an exothermic reaction, the products have less energy than the reactants, so the excess energy is released as heat to the surroundings. This results in an increase in the temperature of the system and a decrease in the temperature of the surroundings. In contrast, an endothermic reaction absorbs energy from the surroundings, leading to a decrease in the temperature of the system and an increase in the temperature of the surroundings.
• Describe the role of enthalpy in understanding exothermic reactions.
  • Enthalpy is a measure of the total energy of a thermodynamic system, including the energy required to create the system (internal energy) and the work required to make room for it by displacing its environment (pressure-volume work). In an exothermic reaction, the change in enthalpy, denoted as ΔH, is always negative, indicating that the reaction releases energy in the form of heat to the surroundings. The magnitude of ΔH provides a quantitative measure of the energy released during the exothermic process.
• Analyze the practical applications of exothermic reactions in everyday life and industry, and explain how the released heat can be utilized.
  • Exothermic reactions are commonly used in everyday life, such as in the burning of fuels, the cooking of food, and the production of hand warmers. In these cases, the released heat is used directly to provide warmth or to drive other processes. In industrial and chemical processes, exothermic reactions are often preferred because the released heat can be used to drive other processes or generate electricity. For example, in the production of ammonia, the exothermic reaction can be used to generate steam, which can then be used to power turbines and generate electricity. The efficient utilization of the released heat in exothermic reactions is an important consideration in the design and optimization of industrial and chemical processes.

Related terms

Endothermic: An endothermic process is a chemical reaction or physical change that absorbs energy in the form of heat. This means that the products of the reaction have more energy than the reactants, and the excess energy is taken from the surrounding environment.

Enthalpy: Enthalpy is a measure of the total energy of a thermodynamic system, including the energy required to create the system (internal energy) and the work required to make room for it by displacing its environment (pressure-volume work).

Thermochemistry: Thermochemistry is the study of the heat energy changes that occur during chemical reactions and physical transformations. It is a branch of thermodynamics that focuses on the relationship between chemical reactions and energy changes.