States of Matter

• 2 racquetballs (drop one into the LN₂ right away)
• Liquid Nitrogen
• cryo gloves
• tongs

Key points:

• Racquetballs are solid.
• Even though they are solid, the molecules can flex a little, like the people in our first demo when they were a solid.
• Freezing a racquetball causes the molecules to hold on tighter than usual.
• The racquetball isn’t flexible anymore.
• When you try to make something bend that isn’t flexible anymore, it breaks.
• Even if the racquetball doesn’t break right away it won’t bounce as well.

Warnings:

• Use the glove to hold the frozen racquetball. It will protect your hand, and keep the racquetball cold longer.
• Don’t throw the racquetball at or over the audience.
• Try to keep kids from picking up pieces of the frozen racquetball. It won’t do any serious harm, but it’s still cold.

Things to talk about:

• Recap the state transitions we have already shown them.
• Mention that this is a little different than the other demos we have shown them.
• We want to show them what happens when we take something that is already solid and make it really cold.
• Show off the normal racquetball and bounce it to show them how it behaves.
• Talk about why it is flexible.
• Take the frozen racquetball out of the LN₂. You may want to mention that it will act differently when it is cold.
• Toss both racquetballs into the air at the same time.
• After one of them (hopefully) breaks, explain why the racquetball got brittle when it was cold.

Click here for the Adobe PDF version of this demo (text only), for printing purposes.