2/24/12 OBJECTIVE: Students will identify physical and chemical properties. WARM-UP: Identify 5 common elements. HOMEWORK: None.

Chemical and Physical Properties

1. Physical Property Any characteristic of a material that can be observed or measured without changing the composition of the substances in the material. Any characteristic of a material that can be observed or measured without changing the composition of the substances in the material.

2. Examples of Physical Properties Viscosity- resistance to flowing Viscosity- resistance to flowing Conductivity Conductivity Malleability- ability to be hammered without shattering Malleability- ability to be hammered without shattering Hardness Hardness Melting and Boiling Point Melting and Boiling Point Density Density

3. Chemical Properties The ability to produce a change in composition of matter. The ability to produce a change in composition of matter. Ex: flammability- ability to burn in the presence of oxygen Ex: flammability- ability to burn in the presence of oxygen Reactivity- how readily a substance combines chemically with other substances Reactivity- how readily a substance combines chemically with other substances

4. Evidence of a Chemical Change Change in color Change in color –Silver bracelet turns black over time –Match burns- turns black –Statue of Liberty (made of what metal) Production of a gas (vinegar and baking soda) Production of a gas (vinegar and baking soda) –Bubbles form when mixed together –Bubbles make a cake rise when baking Form a precipitate Form a precipitate –A solid that forms and separates from a liquid mixture –(milk and lemonade)

How do you tell the difference between chemical and physical properties? Let’s look at some examples and see if we can come up with a definition for a chemical property and a physical property. Let’s look at some examples and see if we can come up with a definition for a chemical property and a physical property. We will show you the substance, We will show you the substance, you write on the white board if you predict that the substance is a “chemical” or “physical” property. “chemical” or “physical” property.

5. Chemical or Physical Property Rotten egg Rotten egg Lemon juice Lemon juice Tape Tape Alka Seltzer and water Alka Seltzer and water Burning candle Burning candle

Chemical or Physical Property Torn piece of paper Torn piece of paper Orange string Orange string Aluminum foil Aluminum foil Ice melting Ice melting Broken wood Broken wood

Class Demonstrations 1. Heat an ice cube in a beaker. 1. Heat an ice cube in a beaker. 2. Boil some water. 2. Boil some water. 3. Melt some wax and then allow it to cool. 3. Melt some wax and then allow it to cool. 4. Break a wooden splint into several pieces. 4. Break a wooden splint into several pieces. 5. Light a match. 5. Light a match. 6. Add some lemon juice to milk. 6. Add some lemon juice to milk. 7. Add vinegar to baking soda. 7. Add vinegar to baking soda. 8. Add salt to water, stir, then boil to dryness. 8. Add salt to water, stir, then boil to dryness.

Class Demonstrations 9. Add a small piece of zinc to hydrochloric acid. 9. Add a small piece of zinc to hydrochloric acid. 10. Add a drop of phenolphthalein to a solution of sodium hydroxide. 10. Add a drop of phenolphthalein to a solution of sodium hydroxide. 11. Add a few drops of vinegar to chalk. 11. Add a few drops of vinegar to chalk. 12. Sharpen a pencil and collect the shavings. 12. Sharpen a pencil and collect the shavings.