Notes: Phases of Matter and Phase Changes

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1 Name: Date: IP 670 Notes: Phases of Matter and Phase Changes There are four main phases of matter: We are only going to talk about the first three today. Solids Liquids Gases Molecular Molecules Wiggle Molecules Slide by each Random Motion Motion other Volume Definite Volume Definite Volume Indefinite Volume Shape Definite Shape Indefinite Shape Indefinite Shape Kinetic Energy Low Kinetic Energy (little motion) More Kinetic Energy (More Motion) Lots of Kinetic Energy (Lots of Motion) Heat Transfers 1. We have learned that when heat is transferred to a substance, the substance can experience an in temperature. 2. We have also learned that when heat is released by a substance, the substance can experience a in temperature. 3. However, temperature changes are not the only possibility! o Heat transfers can also result in changes!

2 Teacher Demo a. What phase of matter is the substance inside the test tube? b. What substances are inside of the beaker? c. When the test tube of water touches the cold snow, does it give heat to the snow or take heat from the snow? d. What will the water do when it gets cold enough? e. Sketch the graph in the space below: Temperature ( C) Time (sec)

3 Temperature of a Substance as Heat is Added at a Constant Rate e. Temperature b. c. d. a. Heat Being Added A Substance Absorbs Energy f. A solid will experience a temperature. g. Then, at its point, the solid will melt. h. After melting is complete, a will experience an increase in. i. Then, at its boiling point, the liquid will. j. After boiling (or vaporizing) is complete, the gas will continue to experience an in temperature.

4 Temperature of a Substance as Heat is Released at a Constant Rate a. b. Temperature c. d. e. Heat Being Released A Substance Releases Energy a. A gas will experience a in temperature. b. At its point of (same temperature as boiling), the gas will condense and become a. c. Once condensation is complete, the liquid will experience a decrease in. d. At its point (same temperature as melting), the liquid will freeze. e. Once freezing is complete, the solid will experience a decrease in.

5 Four BIG ideas When a substance absorbs heat energy, it can experience a phase change OR a change. And when a substance releases heat energy, it can experience a phase change OR a temperature change. Phase changes require transfers. A substance experiencing a phase change always remains at constant. During a temperature change, only phase of matter is present. During a phase change, phases of matter must be present. Melting A change of phase from to. Example #1: holding an ice cube in your hand. Example #2: Putting butter on hot corn on the cob. Vaporization A change of phase from to. Two types: o Boiling o Evaporation

6 Boiling A change of phase from liquid to gas that takes place the surface of a liquid. The gas that forms below the surface forms bubbles and the bubbles are buoyed upwards to the surface where they escape. It is important to note that it is the high temperature of the water, not the boiling process, that cooks food. Example) Boiling water on the stove Evaporation Change of phase from liquid to gas that takes place at the of a liquid. Molecules at the surface of a liquid may be bumped enough to give them enough kinetic energy to break free from the liquid. They can leave the surface and fly into the space above the liquid. They now comprise a vapor, molecules in the gas phase. Example ) Stepping out of the shower.

7 Condensation The changing of a to a. Vapor molecules collide with the slower moving molecules of a cooler surface. The vapor molecules give up so much kinetic energy that they can't stay in the gaseous phase. They condense. Example #1) Muggy Boston Days Example #2) A Steam Burn Freezing When energy is continually withdrawn from a liquid, molecular motion until the forces of attraction between the molecules cause them to get closer to one another and to form a solid. Impurities in water, such as salt, lower the freezing temperature since the foreign molecules get in the way of water's crystalline structure. Example ) Freezing ice cubes in the freezer