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
Changes in enthalpy (ΔH) refer to the difference in heat content between products and reactants at constant pressure during a chemical reaction.
Related terms
Enthalpy of Formation (ΔHf): This term refers to the change in enthalpy when one mole of a substance is formed from its elements - it's like calculating the cost of making a homemade meal from scratch.
Enthalpy of Reaction (ΔHr): This term describes the total energy absorbed or released during a chemical reaction - similar to figuring out if you made or lost money after selling something you produced.
A spontaneous process occurs without needing additional energy input once started, like an investment that continues to grow on its own without needing more funds.