Hess's Law states that the total enthalpy change for a chemical reaction is the same, regardless of the pathway taken, as long as initial and final conditions are the same. This principle is a direct consequence of the law of conservation of energy, allowing the calculation of enthalpy changes for reactions where direct measurement is challenging.

Hess's Law

total enthalpy change

A chemical reaction is a process where substances, known as reactants, are transformed into different substances, called products, through the breaking and forming of chemical bonds. This transformation involves changes in energy and is governed by the principles of conservation of mass and energy.

chemical reaction

pathway taken

initial and final conditions

The law of conservation of energy states that energy cannot be created or destroyed, only transformed or transferred from one form to another. This principle is fundamental in physics and ensures that the total energy in an isolated system remains constant over time.

Your Lessons