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Warm Up October 1 , 2013. Sophia is boiling water in a glass tea kettle. She notices bubbles forming on the bottom of the kettle that rise to the top and wonders what’s in the bubbles. She asks her family what they think, and this is what they say : Dad: “They are bubbles of heat.”
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Warm Up October 1, 2013 Sophia is boiling water in a glass tea kettle. She notices bubbles forming on the bottom of the kettle that rise to the top and wonders what’s in the bubbles. She asks her family what they think, and this is what they say: • Dad: “They are bubbles of heat.” • Calvin: “The bubbles are filled with air.” • Grandma: “The bubbles are an invisible form of water.” • Mom: “The bubbles are empty – there is nothing inside them.” • Lucy: “The bubbles contain oxygen and hydrogen that separated from the water.” Which person do you most agree with and why? Explain your thinking.
Physical Properties • Physical Properties are properties that can be measured or observed without changing the identity of the substance. • Examples: color, odor, temperature, density, state of matter (solid, liquid, gas), boiling point, melting point, shape, size, texture
Physical Changes • A Physical Change is a change in matter that does not affect the identity of the matter. • Examples: Changes in state (solid, liquid, gas), changes in shape, separating a mixture
In a physical change, the physical properties of a material do not change. Before the water boils, it has a boiling point of 100°C. After: Water Vapor After the water boils, it has a boiling point of 100°C. Before the water boils, it has the chemical formula H2O. Before: Liquid H2O After the water boils, it has the chemical formula H2O. Before the water boils, it is a substance that is odorless and colorless in its liquid state. After the water boils, it is a substance that is odorless and colorless in its liquid state.
Chemical Changes • A Chemical Change is a change in matter that changes the identity of the matter. • Examples: burning, baking, rotting, digesting, decomposing, synthesizing
In a chemical change, the physical properties are different before and after the change because a new substance with new properties is formed. Before the sugar is a white, powdery solid. After the caramel is a brittle, amber colored solid. Before the sugar is odorless. After the caramel has sweet odor.
Physical Change or Chemical Change? Electrolysis of Water (breaking H2O into H2 and O2)
Physical Change or Chemical Change? Melting Candle Wax
Physical Change or Chemical Change? Chopping Onions
Physical Change or Chemical Change? Apple Rotting
Physical Change or Chemical Change? Digesting a sandwich
Law of Conservation of Matter The Law of Conservation of Matter states that matter cannot be created or destroyed in physical or chemical changes. In a chemical change, however, matter can change forms or be rearranged.
Cool Down • Title: Chemical and Physical Change Double Bubble Map
Homework • P. 72 #1a-c & #2a-c • No Quiz Thursday!