Physical and Chemical Changes

1. Physical and Chemical Changes

2. Physical Change • 1.The substance itself doesn’t change. • 2. No new substances are made. • 3. Most of the time it can easily be reversed.

3. Examples of physical changes • a) Crushing or breaking • b) Phase changes • Liquid  Gas Vaporization • Gas  Liquid Condensation • Liquid  Solid Solidification (Freezing) • Solid Liquid Fusion (Melting) • Solid  Gas and • Gas  Solid Sublimation

4. Chemical Change • 1.The substance itself changes. • Molecules are broken apart, • Atoms are rearranged and put back together to make new molecules. • 2. A new substance is made: • eg. Smoke, gas bubbles, solid. • 3. It cannot be easily reversed. • Examples of chemical change: • burning • rusting -- a permanent colourchange • production of Light • change in temperature

5. Physical and Chemical change Worksheet Can the student apply their knowledge? 1 2 3 4 5 In the space beside each question place P or C denoting a physical or chemical change. Explain why? __P__1. Clothes drying on the line. Phase Change __C__2. Bread rising. ______Yeast ferments and produces CO2__________________________ __P__3. Sublimation of iodine. _____Phase change___________________ _C__4. Hydrogen exploding. ________Production of light sound heat, creation of new substances___ _C__5. Bicycle rusting. ______Creation of new substance FeO___________________ _P__6. Solidifying candle wax. ______Phase change_________________ _P__7. Melting ice cream. __________Phase change_________________ _P__8. Hammering aluminum into foil. ___No new substance is made. _____ _P__9. Dissolving sugar in tea. ____May be separated by distillation___________________ __C_10. Baking a cake. _________Cannot be reversed___________________