A reaction with a negative change in free energy is described as:

1. The sign of the free energy change tells you which way a reaction runs on its own. 2. If energy is released during a chemical reaction, the resulting value is a negative number. 3. Reactions that have a negative free energy change and consequently release free energy are called exergonic reactions. 4. These are also referred to as spontaneous reactions, because they can occur without energy being added. _Source: OpenStax Biology for AP(R) Courses (CC BY 4.0), Ch 6 'Metabolism', sections 6.1-6.5_