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The Swirls Around Us

In this demonstration, students will observe a solid ice cube melt into both hot and cold liquids.

This demonstration is a great visual for students to observe the impact of temperature on melting and can be used as an introduction to investigations of other properties of matter such as density. 

The change of state from a solid to liquid is called melting. It requires the solid to be at its melting point temperature in order for its molecules to have enough kinetic energy to be able to flow, move more freely, and have attain the properties of a liquid.

This simple demonstration using different temperatures of water and ice cubes will highlight the idea that temperature affects the transition of phases.

Objectives

  • Describe the properties of solids and liquids.

  • Describe the process of melting and the role of temperature.

  • Understand the transitions between states of matter.

  • Describe different properties of matter.

Materials

  • Per Demo or Class:
    beakers or clear containers for liquids
    hot water, cold water and other types of liquids (salt water, oil) for the extension activities
    coloured ice cubes made with water dyed with food colouring. At least 1 tray is recommended.

    Teaches Tip: If you plan to have groups/pairs of students observe the demonstration on their own and/or if you plan to implement the extension activities, make 2-3 trays of ice.

Key Questions

  • What is the name of the transition from solid to liquid?
  • Which liquid medium does the ice cube melt faster in?
  • How do we tell that the ice melts faster in one beaker than the other?

What To Do

Preparation:

  1. Make ice cubes with water coloured with food colouring. At least 1 tray of ice cubes is recommended.

Demonstration:

  1. Set-up beakers of different liquids. The hot water may be stored in a thermos and then poured in prior to dropping the ice cubes in.
  2. Have the coloured ice cubes ready to be dropped in to each beaker.
  3. Have student volunteers drop ice cubes into each beaker. Have them drop the ice cube slowly into the hot water as there may be a bit of some splash back.
  4. Have the students observe the swirling liquids. As the ice cube melts, what happens to the liquid?

Extensions

  • Try different liquids other than water like oil or salt water.
  • Make observations as to what happens with these different liquids when the ice cube melts. For instance, when an ice cube is placed in salt water, the ice cube melts and creates a freshwater layer. Fresh water is less dense than salt water and therefore will float on top. As the layer of fresh water increases, the temperature of the water decreases causing the ice to melt more slowly. In the case of a freshwater medium containing a freshwater ice cube, the densities are the same so there is a continuous flow of warmer temperature because of the convection currents that are created from the warm stream of liquid.