Why we need thermodynamic potentials |internal energy | enthalpy | Helmholtz | Gibbs free energy

Why does thermodynamics need four different potentials—Internal Energy (U), Enthalpy (H), Helmholtz Free Energy (F), and Gibbs Free Energy (G)? If internal energy already contains all the information, why not just use that? In this video, I answer exactly that question. We start by defining each thermodynamic potential and their "natural variables." Then, I explain—with concrete examples—why controlling entropy directly is nearly impossible, and how each potential is tailored for specific experimental conditions like constant pressure (enthalpy), constant temperature (Helmholtz), or both (Gibbs). ✅ What you'll learn: The definitions of U, H, F, and G What "natural variables" mean and why they matter Why we need more than just internal energy Real-world examples: calorimetry (constant P), batteries (constant T), and chemical reactions (constant T & P) ⚠️ Note: This video covers the conceptual introduction and the why. The mathematical derivations of the partial derivatives (∂H/∂S, ∂F/∂T, etc.) will be covered in a separate follow-up video. 📌 Next video in the series: Derivation of Partial Derivatives for Thermodynamic Potentials 🔔 Don't forget to like, subscribe, and hit the bell so you don't miss the derivations! #Thermodynamics #Physics #Enthalpy #GibbsFreeEnergy #HelmholtzFreeEnergy #ChemicalEngineering #PhysicalChemistry #education #internalenergy #statisticalmechanics