# Hydrogen Rocket

## Summary

A modified Pringles can is filled with hydrogen and lit. It burns for about 30 seconds before turning into a rocket, shooting the can into the air.

## Hazards

Stand back, protect ears (very loud). Fill with hydrogen for at least 30sec to ensure cylinder is filled with hydrogen.

Hydrogen Gas

## Materials

• "rocket"
• hydrogen gas cylinder
• matches
• ring stand with iron ring and clay triangle

## Procedure

1. Attach an iron ring to a ring stand and rest a clay triangle on the iron ring.
2. Use a hydrogen gas cylinder to fill the "rocket" with hydrogen gas. (The rocket consists of a cardboard cylinder with a metal bottom and a plastic cover. The metal bottom has a small nail sized hole in the middle. The plastic cover has a pencil-sized hole in the middle)
3. Once you are certain the rocket is filled with hydrogen, turn off the gas cylinder and place the rocket on the clay triangle such that the end with the plastic cover is down.
4. The hydrogen will begin to issue from the upper hole of the rocket. Light the hydrogen with a match. (Be prepared, if you did not completely fill the rocket with hydrogen it will explode when you light it.)
5. The hydrogen will burn with a yellow flame for about 1 minute. As the hydrogen is consumed the flame will become smaller and smaller and air will be drawn in through the hole in the bottom. Just before the mixture explodes a slight whistling can be heard. When the mixture explodes the plastic lid on the bottom will fly off and the can will shoot about ten feet into the air.

## Discussion

The hydrogen burns as it escapes at the top of the rocket. Air rushes into the rocket through the large hole at the bottom to compensate for the partial vacuum inside. When the ratio of hydrogen to oxygen reaches a particular value, the gas undergoes an explosive reaction.

$$\ce{ 2H2_{(g)} + O2_{(g)} -> 2H2O_{(g)} ~~~~ \Delta G^{{o}}_{Rxn} = -457.2KJ/Mol }$$