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Dublin: 13 °C Tuesday 5 November, 2024

Freeze water in an instant... and more Science Week magic*

(*it’s not magic, it’s science)

IT’S SCIENCE WEEK 2012 ladies and gentlemen and the theme this year is Everyday Experimenting, so put on your protective goggles,  fire up the bunsen burners, get out the graduated cylinders and start doing science!

This old chestnut… Mentos v Coke

The Science Week folks set us a little challenge and sent us the materials necessary to carry out the Diet Coke and Mentos experiment:

You need:

  • A bottle of Diet Coke
  • A packet of Mentos
  • An outside space

Do science:

  • Take the cap off the coke
  • Unwrap the Mentos
  • Tip the mentos into the bottle of coke
  • Stand back

What’s happening here?

When you drop the Mentos into the coke the carbon dioxide in the bubbles in the coke reacts with the porous surface area of the sweets. Due to the high surface area of the sweets millions of bubbles are released at once, resulting in a rapid gas release (snigger).

Here’s Weezer with a demonstration (at 0.32 to be scientifically precise):

YouTube/WeezerVEVO

Supercool water!

You need:

  • A bottle of distilled water (no cheating with tap water or mineral water, it won’t work). You can buy distilled water from a hardware store or from a pharmacy
  • A freezer

Do science:

  • Place the unopened bottle of distilled water in the freezer and leave for two-and-a-half hours
  • Carefully remove the bottle from the freezer after dancing around it for two-and-a-half-hours
  • The water should still be liquid… if it’s frozen, you’ve made a balls of it
  • Bang the bottle on a table, and watch it freeze instantly OR pour the super cooled water onto an ice-cube and watch the water freeze backwards into the bottle

What’s happening here?

When water freezes, ice crystals form around tiny impurities in the water. However distilled or purified water contains few impurities so the water doesn’t freeze at zero degrees Celsius, so when you disturb the super cooled water, it freezes instantly.

How strong is an eggshell?

You need:

  • 4 raw eggs
  • A pencil
  • A glass
  • Scissors
  • A sheet of A4 paper
  • A ruler
  • Some heavy books

Do science:

  • Using a pencil, draw a line around the widest part of one of the eggs
  • Crack the pointed part of the egg.
  • Pour the contents into a glass (omlettes for lunch, wahey!)
  • Carefully break off the pieces of the eggshell down to near the pencilled line.
  • Use the scissors to nip off the shell near the line – try to keep the rim of the shell as even as possible
  • So the same thing with the other three eggs
  • Draw a rectangle (about 18 cm by 12 cm) on the piece of paper and place an egg shell in each corner.
  • Place some heavy books on top of the eggshells, like so:

What’s happening here?

The dome shape created by cutting the eggshell is strong because it is made up of a number of arches, which spread weight placed on top of it evenly. The weight of the books placed on the eggshells is evenly spread and, voilá, they don’t break.

For more science madness visit ScienceWeek.ie>

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Author
Emer McLysaght
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