Motivation

Hydrogen peroxide is used in many experiments as a source of oxygen. It is famous for the elephant toothpaste experiment. H₂O₂ is also used for many explosive syntheses (which I won’t be covering here). Unfortunately, it has become increasingly difficult to obtain 30% hydrogen peroxide. H₂O₂ is sold in almost every grocery store as 3% stabilized solution. It is a simple matter of heating the solution to drive off 10x the water to concentrate it. One problem arises because hydrogen peroxide decomposes easily in the presence of light or heat. There are many videos out there about concentrating H₂O₂, so I would just like to mention an adaptation I found that helps quell this problem.

Process and Experimental Set Up

H₂O₂ is subjected to elevated temperatures. Air is passed over the liquid to facilitate evaporation. Care should be taken to minimize foreign particles in the air stream.

My system consists of a candle warmer and a pyrex bowl under an aluminum foil “hat” with a computer fan blowing over it. The foil provides a cover against particles and light (as much as possible anyway).

Notes

The maximum concentration using this method is about 30%. The higher the temperature the faster the decomposition but also the faster you will obtain the end product. If you are willing to wait long enough, you can just let the peroxide sit out. It will slowly (many days or weeks) evaporate. I don’t know exactly what the concentration would be since 70% peroxide spontaneously detonates at room temperature. I bet you could use chemical dehydration with silica gel or something similar. That would virtually eliminate particles and decomposition… that will be next.

Watch this video for a good demo of the project (not mine).