S140: Prep Notes

Introduction

A balloon filled with helium and one filled with hydrogen are ignited.  Hydrogen provides a loud explosion and flame.

 

He(g) + O2(g) → N.R.

2H2(g) + O2(g) → 2H2O(g)

Supplies

Short List

  • Tape
  • Yardstick
  • Matches
  • Earplugs
  • Fire extinguisher
  • Goggles

 

Prior to Lecture  (prep time ~ ? min.)

  1. Immediately before lecture, inflate desired number of balloons with helium and hydrogen.  Attach ~6ft. string to each.
  2. Tape the ends of the strings to the floor or to the lecture table at such a height that the balloons can be reached with the candle on the yardstick.
  3. Assemble the following:
  • Attach the candle to the yardstick.

 

To Conduct Demonstration

  1. Light the candle on the end of the yardstick and lower the lights.
  2. Bring the candle under the helium balloon until the tip of the flame touches the balloon.  Be prepared for an explosion.  DO NOT LIGHT THE STRING ON FIRE!
  3. Repeat with the hydrogen balloon.  The explosion will be much more violent.

Demo Time: ~2 minutes

 

 

Safety and Disposal

Hearing damage can occur with especially large balloons or small rooms.  Earplugs or ear protectors maybe worm.

 

Acknowledgment

Margaret Asirvatham & Lyn Pierce, Summer 1987

Lora Ruffin and Michael Polk, Summer 2009

 

Revised 7/2009