Students will evaluate the evidence of ice mass loss, and explain how freshwater entering the ocean can affect global climate systems. (Instructions for students are on the last two pages of
Station 5: Queen Maud Land of the Companion Reader).
Materials Needed
- Ice cube tray
- Distilled water
- Blue food coloring
- 1-liter plastic bottle
- Salt
- Access to a freezer
Instructions
- Fill an ice cube tray with distilled water. Add blue food coloring to the water. Place the tray in the freezer until solid.
- Make a saltwater solution using 35 grams of sodium chloride (salt) per 1,000 ml of distilled water. Place the water in the refrigerator.
- Cut a 1-liter clear plastic bottle to form a funnel from the top one-quarter of the bottle and a container for water from the bottom three-quarters of the bottle.
- Test common objects to find one that floats in the cold saltwater, but sinks in freshwater. The object needs to be small enough to fit in your bottle. The object’s buoyancy will be used to observe a change in density due to a change in salinity. Consider criteria and constraints that affect your design options.
- When the ice and saltwater are ready, fill the bottom of the bottle with 250 ml of cold saltwater. Mark the water level using a permanent marker. Measure the temperature of the water. Leave the thermometer in the water for later temperature readings.
- Add the object you will use to observe changes in density due to changes in salinity.
- Invert the top of the bottle and place it so it rests neck down on the rim of the bottom of the bottle. Place the blue-colored ice cubes in the funnel shaped bottle top. The ice cubes will be playing the role of land ice.
- Observe and record what happens as the freshwater ice cubes melt into the saltwater below.
- Use your observations to describe the effect of melting land ice on oceans.
