Changes in matter_revised
- 1. Physical and Chemical Changes of Matter
- 4. What is “Change”? It is the act of altering a substance. An event, NOT a trait. Before condition After condition. Can be PHYSICAL or CHEMICAL.
- 5. All Changes of Matter Involve Energy being Tranfered and Transformed Energy always moves between the system and the surroundings during changes of matter. System = the chemicals of interest Surroundings = everything else (including the beaker and thermometer) Energy cannot be created or destroyed, it can only be transferred from place to place and transformed from type to type (Law of Conservation of Energy).
- 6. Physical Change Does not alter the chemical composition or identity of the substance, only the form. Melting ice (change in state or phase) Freezing Kool-aid Tearing paper Boiling water (change in state or phase) Stretching silly putty Making a mixture (ex. Sugar water) Unmixing a mixture (ex. sorting)
- 7. States of Matter The 3 main states of matter: solid, liquid, gas. Changes in state are physical changes (no change in composition). Temperature is caused by the vibrational (kinetic) energy of atoms or molecules. As temperature increases, 1) solids turn to liquids, and 2) liquids turn to gases.
- 9. Definite Shape? Definite Volume? Compressible? GAS N N Y LIQUID N Y N SOLID Y Y N
- 11. Deposition
- 13. States of Matter for H2O
- 14. Chemical Changes Does alter the chemical composition or identity of a substance and makes new substances. Burning paper Digesting food Rotting Iron reacting with oxygen gas A chemical change is also called a chemical reaction.
- 15. Exothermic change - heat moves out the the system into the surroundings. The surroundings get hotter. System Surroundings System System System
- 16. Endothermic change – Heat moves into the system from the surroundings, so the surroundings gets colder! System Surroundings System Surroundings System System Surroundings Surroundings Surroundings
- 17. Evidence for Chemical Reaction 1) Evolution of light.
- 18. Evidence for Chemical Reaction 2) Temperature Change.
- 19. Evidence for Chemical Reaction 3) Formation of a new Gas/Bubbles.
- 20. Evidence for Chemical Reaction 4) Color Changes.
- 21. Evidence for Chemical Reaction 5) Formation of a solid precipitate.
- 22. Is it Physical or Chemical? Change Physical Chemical Melting cheese Burning wood Milk souring Wadding up paper Bicycle rusting