gen-briefly-explain-hess-s-law-and-one-common-misconception-abou-6a14

Briefly explain Hess's law and one common misconception about it.

## Hess's Law **Hess's Law** states that the total enthalpy change of a reaction is the same regardless of whether it occurs in one step or multiple steps. This is because enthalpy is a state function—it depends only on the initial and final states, not the path taken. This allows us to calculate unknown enthalpy changes by combining known thermochemical equations, which is particularly useful when a reaction is difficult to measure directly. ## Common Misconception **Misconception:** "Hess's Law means all reactions must proceed through intermediate steps." **Reality:** Hess's Law doesn't describe *how* a reaction actually proceeds. It's a mathematical tool that lets us add/subtract thermochemical equations to find ΔH values. A reaction calculated using multiple steps via Hess's Law may actually occur in a completely different mechanism (or directly in one step) in reality. The law simply exploits the fact that enthalpy change is path-independent.