Physical Changes Chemical Changes DEFINITION… EXAMPLES… In a physical change the substance changes appearance but is the same substance with the same original molecules. Melting ice cream, Freezing water, Boiling water, Crumple paper, Haircut, Chewing food, Smashing watermelon, Physical Weathering, In a chemical change the atoms break their bonds to form new molecules with new properties. There are new substances formed. Both change matter in some way. Both require energy to change matter. Electrolysis, Rusting, Combustion (which is burning matter) Vinegar combined with Baking Soda Digestion of your food,

Chemical reactions create ______ substances. But, how do you know a new substance was formed? There could be… Energy Change GAS BUBBLES COLOR CHANGE ODOR RELEASED TEMPERATURELIGHT SOLID FORMS

Cold Packs Have you ever used one of those "instant cold packs" that looks like a plastic bag filled with liquid. You hit it, shake it up and it gets extremely cold. What's going on here? The liquid inside the cold pack is water. In the water is another plastic bag or tube containing ammonium-nitrate fertilizer. When you hit the cold pack, it breaks the tube so that the water mixes with the fertilizer. This mixture creates an endothermic reaction -- it absorbs heat. The temperature of the solution falls to about 35 F for 10 to 15 minutes.endothermic