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Investigating Water's States of Matter (0 Favorites)

LESSON PLAN in Physical Properties, Melting Point, Phase Changes, Boiling Point. Last updated May 17, 2017.


Summary

In this lesson, the students will identify properties of different states of matter, and then work in groups to model molecular arrangement in the solid, liquid, and gaseous states of water. This lesson will also help students to understand that the change in state as a physical change and how the solid state of water has unique properties.

Grade Level

Elementary and Middle School

Objectives

By the end of this lesson, students should be able to

  • Model molecular arrangement in the solid, liquid, and gaseous states of water.
  • Identify change of state as a physical change, not a chemical change.
  • Identify the freezing point and boiling point of water.
  • Identify properties of solids, liquids, and gases.

Chemistry Topics

This lesson supports students’ understanding of

  • States of matter
  • Phase Changes
  • Boiling Point
  • Melting Point
  • Physical change

Time

Teacher Preparation: 15 minutes

Lesson: 60 minutes

Materials

  • ½ sheets of computer or construction paper
  • Markers
  • Masking tape
  • Optional Manipulatives:
    • Hot Plate with Boiling Water
    • Room Temperature Water
    • Cold Water
    • Ice
  • Signs for different stations:
    • 100⁰C Boiling Point
    • 21⁰C Room Temperature
    • 4⁰C Almost Freezing
    • 0⁰C Freezing Point/Melting Point

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Students should wash their hands thoroughly before leaving the lab.
  • When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.
  • If using a hot plate to model boiling point:

Teacher Notes

  • This lesson is designed for grades 4-6.
  • Prior to beginning the kinesthetic aspect of this activity, it is important that students have a basic understanding of the three states of matter and that a change in state is a physical change. Some excellent resources that I use in my own classroom include:
  • Groups for this activity should be larger than your typical groups. Separate the whole class into 4 groups, as there will be 4 stations to which each group will rotate. Ideal group size = 6-8 students.
  • Students will spend about 5 minutes at each station, arranging themselves and recording observations for the station that they experienced. After the 5 minute period, have the groups rotate clockwise.
  • Labels and directions for each station:
    • Station 1: Water Vapor: Spread as far apart as you can and move as quickly as possible within your space.
    • Station 2: Liquid Water at Room Temperature: Move closer together than a gas and slow down. Move your arms like you think liquid moves.
    • Station 3: Liquid Water at Almost Freezing: Move closer together than a liquid at room temperature, and continue to move your arms like a liquid.
    • Station 4: Frozen Water (Solid Ice): Spread out to fill the box and lock arms with your group members in a regular pattern.
  • In an ideal situation, you can have a volunteer or teacher’s aide consistently monitoring the Boiling Point station, operating the hot plate to boil water. Students will be able to observe evaporation (liquid water changing to water vapor) at this station prior to modeling the molecular arrangement of water molecules in a gas. If you do not have a helper for this activity, you may either decide to use this part of the activity as a demonstration prior to the activity or personally stay at this station throughout the activity. The downside of remaining at one station is that it will inhibit you from gauging understanding at the remaining stations. You do not want to leave students unattended at this station with the boiling water, as molecules move freely and quickly in a hot gas, and this could cause an accident.
  • The use of manipulatives is optional, so you may consider using them in a separate demonstration or lesson. The benefit of the manipulatives with this particular activity is that students can quickly connect the molecular arrangement to the real world state of water. If you have a particularly large class of students, you may also consider making a 5th station.
  • You will need to set up your signs in 4 corners of your classroom and tape off a square block in each of those stations. The students will arrange themselves as molecules of water as a solid, liquid at room temperature, liquid in almost freezing water, and a solid incised each of the boxes. The box for gas should be larger than liquid for space to move around.
  • This visual can help for comparing water’s states of matter. (Photo Credit)Lesson watersstatesofmatter teachernotes1
  • Additional background information and helpful images (bullets correlate with images below from left to right):
    • Image 1: Water molecules at greater than 100°C (boiling point). Molecules are spaced far part and move very quickly. (photo credit).
    • Image 2: Water molecules at room temperature, approximately 22°C. Molecules are closer together than in a gas and cannot move as quickly.
    • Image 3: Water molecules are almost freezing, 4°C. As molecules get colder, they move even closer together, making them denser. This is why they sink to the bottom. Warm water rises, and cold water sinks. In most substances other than water, the solid state is most dense. As molecules get closer together, they do not move as quickly.
    • Image 4: If water molecules were like most substances, it would sink in its solid state, because that’s when its molecules would be closest together, but it doesn’t. Ice floats in liquid water meaning that its molecules are not closer together but farther apart. They crystallize in a regular pattern with the positive side (hydrogen) attracted to the negative side (oxygen).Capture

For the Student

Background

  • Anything that has mass and takes up space is matter.
  • Matter can exist in three main states: solid, liquid, and gas.
  • Gas molecules are farthest apart and move very quickly. Molecules of gas spread apart to fill the space they are in. It’s hard to see most gases, but they do have mass and take up space.
  • Liquid molecules are closer than in a gas but spread out farther from each other than in a solid and move loosely. Liquids take the shape of the container that they are contained in.
  • Most solid molecules of a substance are packed closely together and move in slight vibrations. Solids keep their own shape regardless of the container they are in.
  • Molecules are arranged differently in water in its solid state (ice) than in most other solids.
  • A change in state is a physical change that occurs when heat is either added or removed from a substance.

Pre-lab Questions

  1. When you blow up a balloon, you blow a mixture of gases into the balloon. How does this indicate that gases have mass and take up space?
  2. When most substances become a solid, molecules move closer together, which makes them more dense. When substances are more dense, they sink. When water, on the other hand, becomes a solid (ice), it floats in liquid water. What does this tell you about the molecules in ice?

Objective

In this activity, you will rotate to different stations to model the arrangement of molecules of water in its different states.

Safety

  • Always wear safety goggles when handling chemicals in the lab.
  • Wash your hands thoroughly before leaving the lab.
  • Follow the teacher’s instructions for cleanup of materials and disposal of chemicals.
  • Exercise caution when using a heat source. Hot plates should be turned off and unplugged as soon as they are no longer needed.

Procedure

Part I: Water Molecule Diagram

  1. Use markers and a half sheet of computer paper to draw a diagram of a water molecule.
  2. Use different colors for the hydrogen and oxygen atoms, and label each.
  3. Label the diagram with the chemical formula (H2O) and name (Water).
  4. Tape the molecule of water diagram to your shirt.

Lesson watersstatesofmatter student1Part II: Station Rotations

  1. Go to your assigned station with your group.
  2. Stand inside the box in your station and arrange yourself as molecules based on the state of matter and directions provided at that station.
  3. Answer the questions and record your observations below for the station that you experienced.
  4. Rotate clockwise in the classroom when the teacher says to rotate.
  5. Repeat steps 2-4 for each station.

Results

Station 1: Water Vapor

Directions: Spread as far apart as you can and move as quickly as possible within your space.

What is the chemical formula of water when it is a gas?

At what temperature does water reach its boiling point to turn into a vapor?

Based on your observations, how do water molecules move when they are in the gaseous state?

Draw a diagram of water molecules in a gas:


Station 2: Liquid Water at Room Temperature

Move closer together than a gas and slow down. Move your arms like you think liquid moves.

What is the chemical formula of water when it is a liquid?

Approximately what temperature is considered room temperature?

Based on your observations, how do water molecules move when they are in the liquid at room temperature?

Draw a diagram of water molecules in a liquid at room temperature:


Station 3: Liquid Water at Almost Freezing

Move closer together than a liquid at room temperature, and continue to move your arms like a liquid.

What is the chemical formula of water when it is a liquid?

What happens to water molecules as they approach freezing?

Draw a diagram of water molecules in a liquid that are almost freezing:


Station 4: Frozen Water (Solid Ice)

Spread out to fill the box and lock arms with your group members in a regular pattern.

What is the chemical formula of water when it is a solid?

At what temperature does water freeze?

Based on your observations, how do water molecules move when they are in the solid?

Draw a diagram of water molecules in a solid:


Analysis

  1. In most solids, molecules pack so tightly together that their molecules can only vibrate slightly, but water acts differently. Instead of packing more tightly together, how do molecules of water arrange?
  2. As you rotated to each station, the molecular structure of your substance (H2O) did not change. A change in state is not a __________________ change; it is a _________________ change.
  3. Each substance has a boiling point and freezing point. Changes in state happen when you either add or remove heat from a substance.
    1. When enough heat is added to a liquid substance for it to reach its boiling point, what happens to the molecules in that substance? What state will it change to? Will that change its chemical formula
    2. When enough heat is removed from a liquid substance for it to reach its freezing point, what happens to the molecules in that substance? What state will it change to? Will that change its chemical formula?

Extension

Think of a glacier, how huge and heavy it is. It is solid ice. How can something so large and heavy float on top of liquid water?