Disappearing Water

This is a really good experiment. Not only will it fool your family and friends but it will also show how modern scientist have produced materials to make our everyday life easier.

What you will need

  1. One nappy
  2. One pair of scissors with adult supervision
  3. Three identical mugs or cups
  4. 50 ml water
  5. An audience to applaud at the end

How to do it

  1. Carefully cut the nappy down the middle, lengthwise.
  2. Having done the cutting you can release the adult for more important work
  3. Shake out the centre so as to collect all the power contained and gather the powder
  4. The powder is called Slush Powder but the scientific name is sodium polyacrylate
  5. Put enough powder to just cover the bottom of one mug. It should be about 2 gm
  6. Place the three mugs on a table or similar
  7. Gather you audience and have them sit down about two meters away

This is the script The Science Boffins use but you can make up your own if you like.

Do you think magic is real?

Show the empty mugs but conceal the bottom of the mug with Slush Powder.

I am going to show you a Science trick. Look at these three mugs. You can see that they are all empty. Now I am going to add a little water to one of the mugs.

Pour about 50 ml of water into an empty mug. 1st Pour.

Now I’m going to mix them around and you must watch carefully to follow the mug with the water.

Switch the mugs as if in slow motion.

Now can you guess which mug has the water? Tease a little if you like. Finally pick up the mug with water and pour it into the other empty mug. 2nd Pour

Oh yes, you were right. Now I’m going to do it again, only a little faster.

This time mix the mugs again but do it much more quickly.

Now can you guess? Again tease. You were right again. Pour the water into the mug with the Slush Powder. 3rd Pour

This time I’m going to do it really fast. Switch them very quickly. Stand in front of the mugs to shield them from view. Play on the howls of protest.

Now can you guess? They will of course be confused. At this stage you can choose how you proceed. Example:

So some of you think it is this mug. OK I need a brave soul who does not mind an early shower. Tip the first EMPTY mug over their head. Nothing comes out. Put the upturned mug on the palm of stooge. OK, what about this one? Pick up next empty mug and repeat.

Well then, it must be this one. Play up the fact you are going to pour water over stooge’s head. Tip the mug and nothing comes out.

Well what happened there. I’ll tell you. At the start I had hidden in the mug some special powder we call Slush Powder. Shake out the slush and it viable let (some of) the children poke it.

Do you know what this is? I bet you have all touched it before, now hold up the finger you touched it with…aaah you just touched the insides of a baby’s nappy - this is sodium polyacrylate and is like a super duper sponge that sucks up 400 times its mass in water. If little … over here drank that much water he would be as big as the school.

What happens to the Water?

The water is absorbed by the slush powder . If you leave the slush for a few days all the water will evaporate and you will end up with the powder again.