Placing marshmallows inside a bell jar and changing the air pressure demonstrates how gases expand and contract, showing the effects of vacuum and differential pressure on porous materials.

1. Place several marshmallows inside a sealed bell jar.
2. Observe their normal size and shape at atmospheric pressure.
3. Turn on a vacuum pump to reduce air pressure inside the jar.
4. Watch as the marshmallows expand due to the trapped air inside pushing outward.
5. Once the vacuum stabilizes, note their maximum expanded size.
6. Slowly release air back into the jar to return to normal atmospheric pressure.
7. Observe how the marshmallows shrink, often ending up smaller than their original size.

Marshmallows in vacuum chamber - MrGrodskiChemistry:

📄 Effects of Pressure: The Marshmallow Experiment - Mensor: https://blog.mensor.com/blog/effects-of-pressure-the-marshmallow-experiment

• Try different foods with air pockets (e.g., sponge cake, bread, popcorn).
• Vary the level of vacuum to see how expansion changes.

• Use caution when handling vacuum equipment.
• Ensure the bell jar is rated for vacuum use to prevent implosion.
• Do not over-pressurize or force materials into the jar.
• Keep hands away from moving parts of the vacuum pump.

• Why do marshmallows expand when air is removed from the jar? (The trapped air inside pushes outward since outside pressure is reduced.)
• Why do they shrink smaller than their original size when air is let back in? (Some trapped air escapes during expansion and cannot re-enter.)
• How is this demonstration similar to pressure changes in airplane cabins or deep-sea diving? (Both involve differential pressure acting on the body or materials.)
• What real-world applications depend on measuring differential pressure? (Aviation, industrial safety, medical devices, and pressure control systems.)