The wild side of water

Published on August 28th, 2012
The wild side of water

You drink the stuff every day, but do you know how much fun you can have with good old H2O? Find out with these awesome experiments…

1. Collapse a can
Can you squash a can without using your hands or any kind of physical force? You can with the power of water…

WHAT YOU NEED:

  • water
  • an empty aluminium Coke can
  • a saucepan
  • braai tongs/thick oven gloves
  • a stove
  • adult supervision!

WHAT TO DO:

  1. Pour one tablespoon of water into the empty Coke can.
  2. Fill the saucepan to about halfway with cold water.
  3. Place the can on the stove and heat until the water inside is boiling and steam is coming out of the can.
  4. Holding the can with the braai tongs or oven gloves (be careful!), quickly place the can upside down in the saucepan of cold water.
  5. Watch (and hear) the can collapse!

HOW IT WORKS:
The cold water in the saucepan causes the water vapour inside the can to condense extremely quickly, creating a sudden vacuum (no air can get it because the can’s opening is submerged in water). The higher air pressure outside the can pushes against its sides, squashing it with a dramatic bang.


2. Make your own slime
The name pretty much says it all… with just three household ingredients, you can make your own green, gooey slime!

WHAT YOU NEED:

  • ¼ cup of water
  • ¼ cup of craft glue
  • ¼ cup of liquid laundry starch
  • food colouring (we recommend green, but any colour will work)
  • a mixing bowl and spoon

WHAT TO DO:

  1. Pour the glue into the bowl.
  2. Add the water and mix.
  3. Add about six drops of food colouring.
  4. Add the liquid starch and mix.
  5. Enjoy your slime – the more you play with it, the stretchier it’ll get and the easier it will be to hold. You can even store it in a Ziploc bag to play with whenever you like.

HOW IT WORKS:
The molecules in the glue are long strands, and when you add the starch, it cross-links the strands (in other words, it holds them together) to create that awesome slimy sensation.


3. Make a mirror egg
Turn a raw egg into an underwater mirror with water and a candle.

WHAT YOU NEED:

  • a raw egg
  • a candle and matches
  • braai tongs
  • half a glass of tap water

WHAT TO DO:

  1. Light the candle and hold the egg over the flame (using the braai tongs) until its surface starts to darken (be careful!). Move the egg around until most of the shell has changed colour.
  2. Leave the egg to cool down for five to 10 minutes.
  3. Gently lower the egg into the water and watch in awe as its surface turns into a silvery mirror.

HOW IT WORKS:
When you hold the egg over the flame, it gets covered in a layer of soot (carbon dust). When you lower the egg into the water, the carbon pushes the water away and holds a layer of air against the shell, giving the shell a mirror-like surface. Over time, the air will dissolve in the water and the reflective effect will disappear.