A helium-filled balloon and a hydrogen-filled balloon are ignited to compare their reactions. The helium balloon produces no reaction, while the hydrogen balloon explodes with a loud sound and flame, illustrating combustion and the differences in gas properties.

1. Fill one balloon with helium and another with hydrogen.
2. Darken the room slightly for dramatic effect.
3. Attach a lit candle to the end of a yardstick to maintain a safe distance.
4. Touch the candle flame to the helium balloon. Observe that it pops but does not react with oxygen.
5. Repeat with the hydrogen balloon. The balloon explodes violently with flame and sound.

Hydrogen vs. Helium Balloon Experiment | Explosion of the Week - Scitech WA:

Exploding Hydrogen Balloons - The Royal Institution:

📄 Combustion – H2 and He Balloon Explosion - University of Colorado Boulder: https://www.colorado.edu/lab/lecture-demo-manual/general-reactions/s140-chemical-rxns-combustion-h2-and-he-balloon-explosions

• Use different balloon sizes to compare explosion intensity.
• Record the reaction with a slow-motion camera for classroom replay.

• Wear ear protection to prevent hearing damage, especially in small rooms.
• Keep observers at a safe distance.
• Do not ignite the balloon’s string — only the gas.
• Use small to medium balloons to limit the explosion size.
• Ensure fire safety measures are in place (extinguisher nearby).

• Why does helium not react when ignited? (Helium is an inert noble gas and does not burn.)
• Why does hydrogen explode with a loud bang? (Hydrogen reacts rapidly with oxygen in the air to form water vapor, releasing a large amount of energy.)
• What is the balanced equation for hydrogen combustion? (2H2 + O2 → 2H2O)
• How does balloon size affect the sound and flame of the explosion?
• Why is hydrogen considered both useful (fuel) and dangerous?