Properties and Changes
- 2. What is a physical property of matter? • A property that can be observed or measured without changing the identity of that matter • Ex: Color, odor, shape, size, etc.
- 3. Thermal Conductivity Definition: The ability to transfer thermal energy (heat) to something else Example: Coffee in a special cup to prevent heat transfer to our hands
- 4. State Definition: The form in which matter exists: solid, liquid, gas, or plasma Example: Ice = Solid Water = Liquid Helium = Gas Lightning = Plasma
- 5. Malleability Definition: The ability to be pounded into thin sheets Example: Aluminum can be pounded flat to make aluminum foil
- 6. Ductility Definition: The ability to be drawn into thin wires Example: Copper is used to make wires
- 7. Example: Alka-seltzer dissolves in water or sugar dissolves in coffee Solubility Definition: The ability for one substance to dissolve into another substance
- 8. Density Definition: Mass per unit volume Example: Lead is used for fishing weights because it is more dense than water
- 9. More information about density... Density = The amount of matter in a given space or volume Density = m Mass v Volume
- 10. More information about density... Most substances have a unique density: Water = 1.00 g/mL Gold = 19.32 g/mL (See page 13 in your book for a bigger list) Density < 1 - The object will float in water Density > 1 – The object will sink in water
- 11. The Magic Triangle Answers are expressed in g/cm3 or g/mL
- 12. CHEMICAL PROPERTIES Chemical properties can ONLY be observed AS the substances are changing into different substances.
- 13. FLAMMABILITY: A material’s ability to BURN in the presence of OXYGEN
- 14. REACTIVITY: How readily (easily) a substance combines chemically with other substances.
- 16. Physical changes are those changes that do not result in the production of a new substance. If you melt a block of ice, you still have H2 O at the end of the change.
- 17. Physical Changes • Physical changes do not result in the formation of a new substance and are reversible. • The following are examples of physical changes: • Melting and freezing • Boiling and condensation • Forming a separable mixture
- 18. If you break a bottle, you still have glass. Painting your nails will not stop them from being fingernails. Some common examples of physical changes are: melting, freezing, condensing, breaking, crushing, cutting, and bending.
- 19. 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!
- 20. Special types of physical changes where any object changes state, such as when water freezes or evaporates, are sometimes called change of state operations.
- 21. Chemical changes, or chemical reactions, are changes that result in the production of another substance.
- 22. Chemical Changes Chemical changes result in the formation of a new substance and tend to be irreversible. The following observations often suggest that a chemical change has taken place: Colour change Evolution (release) of gas Temperature change Solution turns cloudy Change of pH
- 23. Signs for chemical changes Color change Gas formation (fizzing/bubbles) Change in light and temperature Precipitate (solid formation)
- 24. When you burn a log in a fireplace, you are carrying out a chemical reaction that releases carbon. When you light your Bunsen burner in lab, you are carrying out a chemical CHANGE that produces water and carbon dioxide.
- 25. Common examples of chemical changes that you may be somewhat familiar with are; digestion, respiration, photosynthesis, burning, and decomposition.
- 26. Physical or Chemical Change? Painting Wood PHYSICAL
- 27. Physical or Chemical Change? •Burning Paper •CHEMICAL
- 28. Physical or Chemical Change? •Digestion of food •CHEMICAL
- 29. Physical or Chemical Change? •Sugar dissolving in water •PHYSICAL
- 30. Physical or Chemical Change? •Iron turning red when heated •PHYSICAL
- 31. Physical or Chemical Change? •Evaporation •PHYSICAL
- 32. Physical or Chemical Change? •A pond freezing in winter •PHYSICAL
- 33. Physical or Chemical Change? •Melting ice •PHYSICAL
- 34. Physical or Chemical Change? •Cutting wire •PHYSICAL
- 35. Physical or Chemical Change? •Painting fingernails •PHYSICAL
- 36. Physical or Chemical Change? •Cutting fabric •PHYSICAL
- 37. Physical or Chemical Change? •Baking muffins •CHEMICAL
- 38. Physical or Chemical Change? •Shattering glass •PHYSICAL
- 39. Physical or Chemical Change? •Decomposition of old leaves •CHEMICAL
- 40. Physical or Chemical Change? •Wrinkling a shirt •PHYSICAL
- 41. Physical or Chemical Change? •An old nail rusting •CHEMICAL