Changes Physical or chemical?

Physical Change Put a can of cola in the freezer. The water in the cola turns to ice It pushes on the can and may explode. Cleaning up that mess is not so nice. Now ice seems different than water. But its true identity’s the same. What do you say when you see this kind of thing? You call it a Physical Change

Physical Change During a physical change the matter is manipulated in shape, size or appearance however the atomic or molecular arrangement stays in tack. The identity of the object remains the same.

Chemical Changes A CHEMICAL CHANGE ALWAYS RESULTS IN SOMETHING NEW BEING CREATED. Something NEW means you will have a different pure substance

Chemical Changes There are 5 basic types of chemical changes 1.Definite Color change (not a blending) 2.Production of a gas 3.Absorption or Release of Heat 4.Production of Light 5.Formation of a Precipitate

Chemical Change 1.Definite Color change (not a blending): Dramatic change in the color of a substance indicates a new substance is present. Examples: Iron rusting it changes from dull gray to an orange. Leaves changing. Lemon juice in Ice Tea.

Chemical Change 2.Production of a gas: When there is a chemical change sometimes gas is released. This gas is the result of the chemical reaction and the chemical change. When you mix baking powder with vinegar a gas is let loose and it bubbles. That gas is the product of the baking soda and vinegar mixing.

Chemical Change 3. Absorption or Release of Heat: Burning wood is a classic chemical change. When wood burns it becomes ash and it produces heat. This heat is a product produced during the chemical change. Types of Heat Reactions a. Exothermic – Release of energy. b. Endothermic – Absorption of energy.

Chemical Change 4. Production of Light: Glow sticks are very common in showing that light is an indicator of a chemical change. Among other things, the lights from fireworks and the light from lightning bugs are also products from a chemical change.

Chemical Change 5. Formation of a Precipitate : When two liquids combine chemically often there is a solid product that is released. When that solid is insoluble {unable to dissolve in solution} the solid will “fall out” of the solution. The solid is called the precipitate and it indicates that a chemical change has occurred.