Can Corpses Really be Dissolved in Hydrofluoric Acid?
An aqueous solution of gaseous hydrofluoric acid only forms a weak acid with a pKa value of 3.19. Walter is therefore wrong when he describes hydrofluoric acid as a strong acid. It is correct, however, that it has the ability to attack silicon-based compounds, such as glass and ceramics.
SiO2 + 4 HF → SiF4 + 2 H2O
We, the authors, have no practical experience in dissolving biological material in acids. However, the method described in Breaking Bad would seem to require some improvement. Firstly, an oxidizing acid seems more suitable for destroying organic tissue. The separation process for ascertaining the metals contained in biological materials employs nitrous acid (HNO3) [14]. The addition of hydrochloric acid or hydrofluoric acid is recommended to deal with especially resistant matrices. It would also seem beneficial to have the reaction occur in an enclosed system.
In summary, we would buy a suitably-sized robust polyethylene (PE) barrel from the hardware store with a lockable lid, put the body inside, pour in 15 to 20 L of 65 % HNO3, add a few hundred grams of calcium fluoride (CaF2), lock the barrel shut, and allow the chemistry to take its course. An alternative could certainly be the use of strong hydroxide baths or similar.
We would welcome contributions to the discussion of this topic.
Reference
[14] J. Angerer, M. Fleischer, G. Machata, W. Pilz, K. H. Schaller, H. Seiler, M. Stoeppler, H. Zorn, Aufschlußverfahren zur Bestimmung von Metallen in biologischem Material, The MAKCollection for Occupational Health and Safety, Wiley-VCH, Weinheim, Germany, 2002.
Hydrofluoric acid is extremely dangerous even as a weak acid because it can cause severe burns to bones without disturbing skin or muscle. HF is too dangerous for high school science experiments and would certainly not be stored in gallon jugs. Two gallons of HF would do little to dissolve a corpse, but it could be used to dissolve the post-cremation bones effectively