What is the difference between an exergonic reaction and an endergonic reaction? . an exergonic reaction results in a decrease of mass and an endergonic reaction results in an increase in mass. an exergonic reaction results in an increase in mass and an endergonic reaction results in decrease in mass. an exergonic reaction involves release of energy and an endergonic reaction involves absorption of energy. an exergonic reaction involves an absorption of energy and an endergonic reaction involves release of energy