chem whatdriveschemicalreactions

Reactivity 1.1.2 - reactions are described as endothermic or exothermic, depending on the direction of energy transfer between the system and the surroundings

most chemical reactions are exothermic, give out heat to the surroundings and is negative.

some reactions are endothermic, involving a heat transfer from the surroundings to the system. here, the products have more stored potential energy than the reactants, and is positive.