The spooky cauldron experiment!

Things needed-

1. A bowl of water

2. A large bowl

3. A strip of cloth

4. A soapy mixture (water and some dishwashing liquid)

5. Some dry ice (You can get dry ice in large grocery stores or any ice cream shop)

6. A pair of rubber gloves (for safety purposes)

Safety tip- Be careful while handling dry ice as it may damage the skin and should not be handled directly

Directions-

1. Put the rubber gloves on

2. Place a piece of the dry ice into the large bowl and add some water into the bowl (at this point, smoke starts coming out of the bowl making it look like a spooky cauldron)

3. Soak the strip of cloth in the soapy mixture and when it is soaked enough, take the cloth out remove the excess soap. Move the stripe of cloth across the bowl such that a thin film of soap is spread across the surface of the entire bowl.

4. Stand back and watch the bubble grow in the bowl.

How does this happen?

Dry ice is carbon dioxide (CO2) in its solid form. At temperatures above -54.6°C (-69.5°F), dry ice changes from solid ice to gas directly, without becoming a liquid. This process is called sublimation. When water is added to the dry ice in the bowl, it fastens the sublimation process which creates clouds of fog. The thin film of soap that covers the top of the bowl traps this cloud of fog and creates bubbles. The bubble keeps expanding until the pressure inside it becomes too much and the bubble explodes, spilling fog over the edge of the bowl.