2.  When a substance bubbles it may be a clue that a chemical reaction is taking place.

3.  Precipitate- a solid that forms during a chemical reaction of two solutions

4.  When mixing chemicals the product is a different color than the reactants

5.  Can give off light or change temperatures  Endothermic- energy is absorbed or the product is colder than the reactant  Exothermic-energy is released or the product is warmer than the reactant

6. The only definitive evidence is the formation of a new substance