Lesson 7 Just a Phase

Lesson 7 – Just A Phase As ice is heated, you will observe the phase changes that occur. You will also observe melting and boiling points. 2

Lesson 7 – COS 1.0 1.1 1.2 1.3 1.4 1.5 7.0 9.1 3

Objectives Discuss your current knowledge of phase change. Observe what happens to ice as it is heated. Measure the temperature of ice water as it is heated. Plot a graph of your measurements. Interpret your graph and other observations.

Getting Started Answer the following questions: How could you make spaghetti cook faster? Why does ice melt? Why can you play in the snow when its warm outside? Why doesn’t ice melt immediately when you add it to a soft drink? Are things that are boiling always hot? Are things that are frozen always cold? What are some of you own questions about what happens when ice melts and water boils?

Vocabulary Phase or state – solids, liquids and gases are the three main states of matter. Two other states include plasma’s and Bose Einstein condensate’s solid: A phase or state of matter in which a substance has a definite shape and volume Liquid: A phase or state of matter in which a substance has a definite volume but no definite shape. Liquids take the shape of their container. Gas: A state or phase of matter in which a substance has no definite shape of volume.

Lesson 7 – (1-1) Vocabulary melting - the phase change in which a solid turns into a liquid. melting point - the temperature at which a solid turns into a liquid; the same temperature as the freezing point boiling - the process by which a liquid changes into a gas at its boiling point. . boiling point - the temperature at which a liquid changes into a gas; boiling point depends on air pressure.…… 7

Vocabulary Freezing: The change in state in which a liquid turns into a solid freezing point – The temperature at which a liquid turns into a solid (altered by changes in pressure) Vaporization/ evaporation – The change of a substance from a liquid to a gas. Condensation – The change of state from a gas to a liquid Phase change - change from one state to another

Lesson 7 – Question How does heat affect phase changes? 9

Lesson 7 Hypothesis 10

SAFETY Tie back long hair Wear safety goggles throughout the inquiry Be careful when you handle hot apparatus

Lesson 7 Procedure Gather materials. Construct a data table. Pour 1 cm. of water into a beaker. Add ice. Measure and record temp. of ice water. Place beaker on stand over alcohol burner. Record temp. every 30 seconds. When water boils, continue to record temp. for 3 more minutes (30 second intervals). Graph the data. 12

Temperature of water (C degrees) Results L 7.1 Temperature v. time Time (min. and s) Temperature of water (C degrees) Observations 30 s 1 min 1 min, 30 sec 2 min 2 min, 30 sec 3 min 3 min, 30 sec 4 min 4 min, 30 sec 13

Lesson 7 – (1-2) Conclusion Phase changes are dependent on temperature and pressure. Three phases or states of matter: solid, liquid, gas Phase changes take place when molecules lose or gain kinetic energy (heat energy) and can be related to a change in temperature. Lose kinetic energy – molecules move closer – (gas > liquid > solid). Gain kinetic energy – molecules move apart – (solid > liquid > gas) A change of state is not the result of a chemical reaction. 14

Lesson 7 - (2-2) Conclusion The melting point and boiling point of a substance is a characteristic property of the substance. Freezing and melting points are the same. An increased input of heat has no effect on the boiling point of a substance, although it will make a fixed mass of matter change state faster. Substances that boil are not always hot. Many substances melt and boil below 0 degrees C…... 15