Ten Commandments for the Use of Piranha Solution to Clean Glassware

Description

Piranha solution is a very strong acid that is capable of removing almost all residues from laboratory glassware. It is also very dangerous. It should only be used when certain commandments are carefully observed by someone who understands the dangers.

There are several recipes for piranha solution with different mixes of its main ingredients:

(1) concentrated sulfuric acid

(2) 30% hydrogen peroxide, which serves as an oxidizing agent

The mixture is usually 3 parts sulfuric acid to 1 part hydrogen peroxide.

The name piranha may come from:

(1) its frequently bubbling, which resembles a mass piranha feeding

(2) its ability to eat just about anything

Commandment	Comment
Do not make up more than you need at a given moment.
Do not use a peroxide stock solution with a peroxide concentration > 50%.	Typically 30% peroxide is the maximum that should be used.
Do not store the solution in a closed container.
Do not let the solution get into contact with organic compounds, such as in a chemical waste container.	Mixing with organic compounds can result in an explosion.
Do not add sulfuric acid to the hydrogen peroxide solution or mix reagents quickly.	Add the hydrogen peroxide to the sulfuric acid very slowly.
Always wear protective clothing and use the solution in an explosion-proof chemical hood.	The solution can explode, sending shrapnel flying.
Do not attempt to neutralize the solution by adding base.	This can result in explosive decomposition.
Assume that the solution is very hot.	The mixture is exothermic and can be over 100°C
Do not pour down the sink unless it has been completely neutralized and only with large amounts of water.	Active solution can dissolve many metals.
Do not leave the solution unattended or near a flame, especially when it is hot.

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Ten Commandments for the Use of Piranha Solution to Clean Glassware

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