Detailed Product Description:

This kit provides the constituents necessary to create 500ml of

Aqua Regia.  This is an extremely powerful oxidizing solution prepared

from concentrated Nitric Acid (69% HNO₃) and concentrated Hydrochloric

Acid (38% HCL). 

It is the only acidic solution that will dissolve the noble metals such as gold,

platinum and rhodium, and will effectively oxidize anything it comes in

contact with.

Uses:

Typically used for removal of stubborn organic residues from laboratory

glassware, or, in semiconductor processing for removal of deposits from inside

of quartz furnace tubes, it is also popular for gold purification.

Background:

Gold is among the so-called “noble metals,” named as such for their lack of

reactivity.  Gold will not dissolve in concentrated forms of either nitric acid or

hydrochloric acid by themselves.  But mix the two acids together and the

combination of the chloride with an oxidizer becomes a very effective

medium to dissolve gold, platinum, etc.

The colorful name, “aqua regia,” is derived from ancient alchemy.  It is from

The Latin for “royal water,” and is believed to have been discovered in

800 AD by the alchemist Abu Musa Jabir ibn Hayyan.

Formulation:

Note that the often quoted ratio of nitric to hydrochloric of 1 to 3 is a

Chemical ratio and not a volumetric ratio of the available acid solutions. 

Using the concentrations of the acids provided, the effective volume ratio

is 5.44 parts hydrochloric acid solution to 1 part nitric acid solution.

Aqua regia decays after being mixed, so it must always be made up fresh.

The nitric acid slowly works on the chloride ion, releasing highly toxic

chlorine gas.  Also generated is a reddish-orange gas—the also toxic nitrosyl

chloride (NOCl).   It is recommended that 1 part H2O be added if the aqua

regia will be stored for any length of time to minimize the generation of

chlorine gas.   

Precautions:

This cleaning solution can do severe damage to the eyes, skin, mucous

Membranes and lungs.  Extreme caution should be exercised when using

this formulation due to the generation of chlorine gas and nitrous oxides.  

Wear butyl gloves (not latex or nitrile exam gloves), eye protection, and a lab coat.

All work must be conducted under a fume hood.

Warning!  Do not attempt to store aqua regia in a sealed bottle.  The build-up

in chlorine gas pressure will inevitably result in an explosion of the bottle.  Only

mix what is needed and dispose of it when your work is complete.

Read and understand all precautions stated in Material Safety Data Sheet

(MSDS, downloadable below) before using this formulation.

Strong irritant to eyes and skin.  Dangerous by inhalation.  Corrosive to skin

and mucous membranes.  Strong oxidizing agent.  Dangerous fire risk

when in contact with organic materials.

Click here to download copy of MSDS (Material Safety Data Sheet).

Contents & Packaging:

Constituents come packed in amber glass boston round bottles, sized to

produce 500ml of aqua regia.  Contents include 422 ml of hydrochloric acid

and 77 ml of nitric acid.  A separate bottle with vented cap is provided for

containment of the resulting mixture.  If the full 500ml is required, simply

pour all of the nitric acid into the mixture bottle and follow by the addition

of the total contents of the hydrochloric acid bottle.  Generally, however,

much smaller amounts of aqua regia are required and will thus require

measurement.