PACT Due Dates

Project Deep Freeze (Melissa Dietz)

Lesson Plan for 8th Grade Physical Science

Duration: 46 minutes

Chapter 3: Solids, Liquids, and Gases

Principle(s) Investigated:

Students will be able to explain what happens to a substance during changes between a liquid and solid state.

California Content Standards Addressed:

3.  Each of the more than 100 elements of matter has distinct properties and a distinct atomic structure. All forms of matter are composed of one or more of the elements. As a basis for understanding this concept:

d.  Students know the states of matter (solid, liquid, gas) depend on molecular motion.

e.  Students know that in solids the atoms are closely locked in position and can only vibrate; in liquids the atoms and molecules are more loosely connected and can collide with and move past one another; and in gases the atoms and molecules are free to move independently, colliding frequently.

5.  Chemical reactions are processes in which atoms are rearranged into different combinations of molecules. As a basis for understanding this concept:

d.  Students know physical processes include freezing and boiling, in which a material changes form with no chemical reaction.

8.  Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:

e.  Construct appropriate graphs from the data and develop quantitative statements about the relationships between variables.

Materials:

  1. Lab worksheet (see attachment)
  2. Ring stand
  3. Test tube clamp
  4. Thermometer
  5. Stirring rod
  6. Large test tube
  7. Stopwatch
  8. 1000 mL beaker
  9. Ice
  10. Salt
  11. Water

Procedure:

  1. Review the concepts of the molecules discussed the day before, pass out lab worksheet, and explain important points to be careful of in the lab.
  2. The students will go to their previously assigned lab group and start the lab. Lab equipment is already out for them. See lab worksheet attachment (35 minutes). The following is the procedure of the lab, note these are approximate times:
    1. Assemble the lab equipment. (5 minutes)
    2. Make beaker of ice, salt, water and test tube. Clamp and start recording temperature at start and every 30 seconds. (3 minutes)
    3. Stir beaker of salt water until it reaches +2°C. Continue to record temperature, but stop stirring. (2 minutes)
    4. When the temperature reaches -2°C, carefully lift test tube with clamp and drop a small ice cube in liquid water. (5 minutes)
    5. Put test tube back in water, like before, and continue to stir and record temperature. When the temperature reaches -4°C stop recording. (8 minutes)
    6. With the remaining time in class, students will clean up, work on results, conclusion, graph, and questions to answer. After the lab groups have cleaned their station, then I will dismiss them by group. (12 minutes)

Student Prior Knowledge:

        The students have been learning about the nature of matter and the changes of state. This lab helps to supplement their understanding of the different states of matter and allow them to interpret a different type of graph. Furthermore, students understand the differences between endothermic and exothermic reactions.

Explanation:

        As the temperature of the solid is decreasing within the test tube, it is unable to find a pattern for the molecules to align and change its matter of state from a liquid to a solid. Like magnetic marbles rolling too fast past each other, they are unable to align until you slow them down and they can connect. The marbles are like the molecules moving within the test tube. By adding the ice cube, you are allowing the molecules to align and form a pattern.

Questions and Answers:

1.    Explain what happened to the temperature when the ice crystal was added to the water when the temperature of the water was -2.5°C.

        A: The temperature jumped up to 0°C.

2.     What temperature does your graph show for the freezing point of water? How can you tell from your graph that this is the freezing point of water?

        A: My graph shows that the freezing point of water is at 0°C, as the water is freezing, the temperature of         the water stays constant at 0°C.

3.    When the temperature began to decrease below zero, was the water in the test tube completely frozen? How can you tell from the graph?

        A: Yes because once the temperature of the water was completely frozen, the temperature began to decrease below 0°C.

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Norman Herr,
Oct 28, 2010, 1:26 PM
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