enzymes helps control chemical reactions by the chemical in it called collagen when enzymes enter your body they create a chemical reactions and controls the chemical reactions you get by eating too much acids.
Chemical reactions that absorb energy are called endothermic. Chemical reactions that absorb free energy are called endothermic reactions. Chemical reactions that release free energy are called exothermic reactions.
When atoms and molecules come together and split, chemical reactions occur. Atoms gain stability through these chemical reactions. They are rapid reactions that occur at given temperatures and at a chemical concentration.