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Explore water in its three forms

November 12, 2017

Water makes all life on Earth possible. The Bay of Plenty has water everywhere, from freshwater streams and rivers, to estuaries where tidal salt water washes in from the ocean.  Did you know that water is the only thing on Earth that can be all three states of matter – a solid, a liquid and a gas? This week’s investigation will help you to explore water in its three forms.

What you will need

Ice cubes

Flat tray

Magnifying glass

Hot water in a glass or clear plastic container

Cold water in a glass or clear plastic container

Salt

Teaspoon

Pipette or dropper

What you need to do

  1. Put the glass containing cold water in the fridge. Leave for about 30 minutes or longer. When this water is really cold, you can start your experiment.
  2. First, put your ice cubes on the tray and have a close look at them through a magnifying glass. Can you see ‘bubbles’ frozen inside? Is all of the ice cube ‘see through’? What does the surface of the ice cube look like?
  3. Sprinkle some salt on your ice cube and watch what happens. How has the salt changed the surface of your ice cube? You might need to use your magnifying glass to see this.
  4. Collect the cold water from the fridge. You will notice that the sides of the glass are ‘fogging’ up? This is water vapour (a gas) collecting on the sides of the glass due to condensation.
  5. Using your pipette squirt the cold water on your ice cubes. What do you notice? What happens if you do a combination of cold water and salt?
  6. Next, collect some hot water in a glass. You should see streams of water vapour (not steam which is colourless) leaving the surface of the water. This is due to liquid water evaporating.
  7. Using your pipette squirt the hot water on your ice cubes. How does this change the ice cubes?

What is happening

The salt, cold and hot water are changing the matter particles in the ice cubes. These are physical changes like liquid water changing to gas (water vapour) or solid ice changing to liquid water. Using this new knowledge, why not explore which is the quickest method to melt your ice cubes.

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