What is hess law

Hess's Law is a fundamental principle in thermochemistry. It states that the total enthalpy change for a chemical reaction is independent of the pathway taken. This means that if a reaction can occur in multiple steps, the sum of the enthalpy changes for each step will be equal to the overall enthalpy change for the reaction.

This law is useful because it allows us to calculate enthalpy changes for reactions that are difficult or impossible to measure directly. We can use known enthalpy changes of other reactions to determine the enthalpy change of the target reaction.