2 Physical Change A change that affects 1 or more physical properties. Examples – a melting popsicle, cutting wood, dissolving sugar, crushing a canDOES NOT AFFECT THE IDENTITY of the matter.
3 Chemical ChangeOccurs when 1 or more substances change into new substances that have new or different properties.Examples – milk goes bad, Efferdent tablets reacting in water, fireworks going off, baking a cake.
4 Chemical ChangeSigns of a chemical change – change in odor, change in color, release of energy (sound, heat, light), bubbling, precipitate formingPrecipitate – a solid formed when 2 substances dissolved in water form
5 Chemical ChangeChemical properties describe whether a chemical change will occur or will not occurchemical change = chemical reaction
6 Chemical Change vs. Physical Change Chemical change – Changes composition of a substance, or what its made of. Changes its identityPhysical change – Does not change the composition of a substance, only its appearance. Does not change its identity.
7 Reversing a changePhysical change – use physical properties. Usually pretty easy.Chemical change – use chemical properties. Not as easy to do, or sometimes impossible.