Hydrogen Balloon

Hydrogen is extremely flammable with a wide flammability range (4-75% in air). NEVER perform this demonstration near electronic equipment, overhead fixtures, or combustible materials. Ensure adequate ceiling height (minimum 3 meters recommended) and clear the area of at least 2 meters around the demonstration point. Do not allow hydrogen to accumulate near ceiling fixtures. Have a fire extinguisher readily available.

The explosion produces a very loud sound (potentially 120-140 dB at close range). Warn students in advance that the demonstration will be loud. Consider providing hearing protection for students in the front rows, or maintain a safe distance. The sound will startle unprepared students.

Purpose

Igniting a hydrogen-filled balloon produces a dramatic fireball and loud bang, demonstrating exothermic combustion. Contrasting with an inert helium balloon highlights the difference between reactive and noble gases. The sound wave can also be used to discuss acoustics and lecture-hall reverberation.

Bright yellow-orange fireball from an ignited hydrogen balloon, with the candle stick visible entering from the lower right

Figure 1: Fireball produced by igniting a hydrogen-filled balloon with a candle on a stick.

Danger: Hydrogen Safety - Critical

Warning: Hearing Protection Advisory

Purpose

Safety Warnings

Danger: Hydrogen Safety - Critical

Warning: Hearing Protection Advisory

Purpose