Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
The heat of formation refers to the change in enthalpy when one mole of a compound is formed from its constituent elements in their most stable forms under standard state conditions.
Related terms
Standard State Conditions (1 atm and 25°C): These are specific reference states for expressing properties such as enthalpy, entropy, and Gibbs free energy. It’s like having instructions for building your Lego castle under ideal conditions – right temperature, right pressure etc.
This is any process which absorbs energy from its surroundings. It's like the effort you put into building your Lego castle - that energy doesn't just come from nowhere, it comes from you!
This states that the total enthalpy change of a reaction is independent of the pathway between the initial and final states. It’s like saying no matter how you build your Lego castle (step by step or all at once), the total effort required remains the same.