Physical and Chemical Changes

1. Physical and Chemical Changes

2. ? • Why does a glass off ice water sweat? • How does a solid piece of Jello density compare with liquid Jello? • Why does Ice float on water? • What causes the solid to expand when it should contract?

3. Energy • Ability to make change • The total energy of a substances particles due to their movemet or vibration is ______________________________________ • The energy stored in within the chemical bonds of matter is _____________________________ Thermal energy Chemical Energy

4. Matter Changes whenever energy is added or taken away.

5. Changing Matter • Alter the form of a substance, but not its identity. • Tearing a piece of paper • Bending a nail • Phase Change • ie., waterice • Changes the substance into a different substance with different properties. • Burning a piece of paper • Sugar turns into caramel • Baking a cake

6. Explain for each example whether it is a Physical or Chemical Change and why? • iron rusting • eggs cooking • bread rising • Cutting paper • gasoline burning • milk souring • sun tanning • boiling water • dissolving sugar in water

7. Explain for each example whether it is a Physical or Chemical Change and why? • iron rusting (iron oxide forms) Chemical • eggs cooking (fluid protein molecules uncoil and crosslink to form a network) Chemical • bread rising (yeast converts carbohydrates into carbon dioxide gas) Chemical • Cutting paper (cutting usually separates molecules without changing them.) Physical • gasoline burning (water vapor and carbon dioxide form) Chem • milk souring (sour-tasting lactic acid is produced) Chem • sun tanning (vitamin D and melanin is produced) Chem • boiling water (water molecules are forced away from each other when the liquid changes to vapor, but the molecules are still H2O.) Physical • dissolving sugar in water (sugar molecules are dispersed within the water, but the individual sugar molecules are unchanged.) Physical

10. Law of conservation • In every physical and chemical change, the total amount of energy stays the same.

11. Vaporization • Liquid water to water vapor • when a liquid gains enough energy to become a gas

12. Evaporation • When vaporization takes place only on a liquids surface.

15. Boiling • When vaporization takes place throughout a liquid. • Also depends on the air pressure.

18. Condensation • Opposite of vaporization. • Occurs when a gas loses enough thermal energy to become a liquid.

20. Sublimation • Occurs when the surface of particles of a solid gain enough energy to become a gas. • Particles DO NOT pass through the liquid state.

22. http://nuweb.neu.edu/bmaheswaran/phyu121/data/ch04/anim/anim0405.htmhttp://nuweb.neu.edu/bmaheswaran/phyu121/data/ch04/anim/anim0405.htm • http://www.harcourtschool.com/activity/states_of_matter/ • http://www.bgfl.org/bgfl/custom/resources_ftp/client_ftp/ks3/science/changing_matter/index.htm • States of matter • Phase change • Phase change notes • Temperature change

24. Liquid Gas Solid Sublimation Vaporization TE added Boiling Point Condensation TE removed Melting TE added Temperature Melting Point Freezing TE removed Thermal energy