Physical and Chemical Changes How can you to

Physical and Chemical Changes How can you to tell the difference? ? ?

Don’t confuse with Properties of Matter • Physical Properties • Any property that can be observed without changing the object/substance • Anything that can be measured • Examples: • Mass, volume, density • Color, texture, shape • Boiling point, freezing point

Don’t confuse with Properties of Matter • Chemical Properties • A property of matter that can only be observed by altering the composition of the substance • Have to “test” for it and risk changing the objects identitiy • Examples: • Flammability • Reactivity

Physical changes • DOES NOT result in the production of a new substance. NEW

**If you melt a block of ice, you still have H 2 O at the end. **If you break a bottle, you still have glass. **Painting your nails will not stop them from being fingernails.

Some, but not all physical changes can be reversed. You could refreeze the water into ice, but you cannot put your hair back together if you don’t like your haircut!

Physical Change • Substance may seem different, but the way the atoms link up is the same.

It’s a physical change if… • It changes shape • It changes size

It’s a physical change if… • It changes phase • freezes • Boils • evaporates • condenses

It’s a physical change if… • It dissolves

Chemical Change • Changes the organization of atoms and molecules • Makes new substances

**When you burn a log in a fireplace, you release carbon. **When you light your Bunsen burner in lab, you produce water and carbon dioxide. **When you mix baking soda and vinegar, you produce CO 2.

Signs of a Chemical Change

It could be a chemical change if…. 1. Production of heat 2. Production of light • Temperature changes without heating/cooling • It burns • Energy from reaction is being released

It could be chemical change if. . . 3. Production of sound • Energy from reaction is being released

It could be chemical change if. . . 4. Change in odor • Or taste • It changing its properties

It could be chemical change if. . . 5. It changes color • (that was not already there) • It changing its properties

It could be a chemical change if. . . 6. It produces a gas • It bubbles • It fizzes • It foams • The gas is the new substance

It’s a chemical change if. . . 7. It forms a precipitate • The precipitate is the new substance

Signs of a Chemical Change 1. Production of heat 5. Change in odor/taste 2. Production of light 6. Change in color 3. Production of sound 7. Formation of precipitate 4. Production of gas

More examples of chemical changes… digestion, respiration, photosynthesis, burning, and decomposition.

Physical or Chemical Change? • Painting a wood block red • PHYSICAL

Physical or Chemical Change? • Burning Paper • CHEMICAL

Physical or Chemical Change? • Sugar dissolving in water • PHYSICAL

Physical or Chemical Change? • Iron turning red when heated • PHYSICAL

Physical or Chemical Change? • Evaporation • PHYSICAL

Physical or Chemical Change? • A pond freezing in winter • PHYSICAL

Physical or Chemical Change? • Melting ice • PHYSICAL

Physical or Chemical Change? • Digestion of food • CHEMICAL

Physical or Chemical Change? • Cutting wire • PHYSICAL

Physical or Chemical Change? • Mixing cake batter • PHYSICAL

Physical or Chemical Change? • Cutting fabric • PHYSICAL

Physical or Chemical Change? • Baking muffins • CHEMICAL

Physical or Chemical Change? • Shattering glass • PHYSICAL

Physical or Chemical Change? • Decomposition of old leaves • CHEMICAL

Physical or Chemical Change? • Wrinkling a shirt • PHYSICAL

Physical or Chemical Change? • An old nail rusting • CHEMICAL