Purpose : to demonstrate diffusion and osmosis
Things Required:
Eye dropper
Vanilla extract
Balloon, use a small size
Shoebox
Directions:
Place 15 drops of vanilla extract inside the deflated balloon. Be careful not to get any of the vanilla on the outside of the balloon. Inflate the balloon to a size that will comfortably fit inside the shoebox and tie the open end. Place the balloon in the empty shoebox. Leave the balloon in the closed box for one hour.
Open the box and smell the air inside.
This Is What Happens:
The air smells like vanilla. The box is still dry.
Science Behind It:
The balloon appears to be solid, but it actually has very small invisible holes all over its surface. The liquid vanilla molecules are too large to pass through the holes, but the molecules of vanilla vapour are smaller than the holes and pass through. The movement of the vapour through the rubber membrane is called osmosis.
The escaped vanilla vapour moves throughout the air in the shoebox. And once the shoebox is open, it moves through the air in the room. This spontaneous movement of molecules from one place to another is called diffusion. If you wait for long enough, the diffusion will result in a uniform mixture of the vanilla vapour and the air with which it mixes
