Energy Change in Reactions Vocabulary

Practice vocabulary flashcards covering the fundamental concepts of thermodynamics and energy changes in chemical reactions.

Thermodynamics

The study of energy change (especially heat energy) in chemical reactions.

Exothermic reaction

A reaction during which heat energy is released into the surrounding environment.

Endothermic reaction

A reaction during which heat energy is absorbed from the surrounding environment.

The principle of conservation of energy

A principle stating that energy cannot be created or destroyed, it can only be transferred from one form to another form of energy.

Enthalpy ($H$)

The heat content of a substance at constant pressure.

Enthalpy change ($\Delta H$)

Also known as reaction heat, it is the energy that is released or absorbed during a chemical reaction at constant pressure.

Negative $\Delta H$ value

Indicates that energy is transferred to the surrounding environment, representing an exothermic reaction where $\Delta H < 0$.

Positive $\Delta H$ value

Indicates that energy from the environment is transferred to the system, representing an endothermic reaction where $\Delta H > 0$.

Bond energy (Bond enthalpy)

The amount of energy required to break a specific bond in a molecule to form neutral atoms.