Facts on Chemical Reactions



  • A candle burning, a nail rusting, a cake cooking — all involve chemical reactions.
  • A chemical reaction is when two or more elements or compounds meet and interact to form new compounds or separate out some of the elements.
  • The chemicals involved in a chemical reaction are called the reactants. The results are called the products.
  • The products contain exactly the same atoms as the reactants but in different combinations.
  • The products have exactly the same total mass as the reactants. This is called conservation of mass.
  • Some reactions are reversible, which means the products can be changed back to the original reactants. Others, such as making toast, are irreversible.
  • Effervescence is a reaction in which gas bubbles form in a liquid, turning it fizzy.
  • A catalyst is a substance that speeds up, slows down, or enables a chemical reaction to happen but remains unchanged at the end.
  • Nearly all reactions involve energy. Some involve light or electricity. Most involve heat. Reactions that give out heat are called exothermic. Those that draw in heat are called endothermic.
  • Oxidation is a reaction in which oxygen combines with a substance. Burning is oxidation; as the fuel burns it combines with oxygen in the air. Reduction is a reaction in which a substance loses its oxygen.