Standard enthalpy of formation

Enthalpy is like the energy that is released or absorbed during a chemical reaction. Think of it like a game where you start with some things and, when you mix them together, you end up with something different. Enthalpy is like scoring points in that game.

Now, the standard enthalpy of formation is like a way to keep score in this game. It tells you how much energy is released or absorbed when one mole of a substance is formed from its constituent elements in their standard states (the way they exist naturally at room temperature and pressure).

Let's say you want to make water by reacting hydrogen and oxygen gases. The standard enthalpy of formation of water is how much energy is released or absorbed when one mole of water is formed from one mole of hydrogen and half a mole of oxygen gas.

This score is important because it helps scientists compare how much energy is involved in making different molecules. And it's a standard score, so everyone can agree on it and use it to compare results.