Hydrofluoric acid (HF) is a solution of hydrogen fluoride in water. Hydrofluoric acid is a highly corrosive acid, capable of dissolving many materials, especially oxides. Because of its high reactivity toward glass and moderate reactivity toward many metals, hydrofluoric acid is usually stored in plastic containers (although polytetrafluoroethylene is slightly permeable to it).
Hydrofluoric acid attacks the silicon oxide in most types of glass. It also dissolves many metals (not nickel or its alloys, gold, platinum, or silver), and most plastics. Fluorocarbons such as Teflon (TFE and FEP), chlorosulfonated polyethylenene, natural rubber and neoprene all are resistant to hydrofluoric acid. Hydrofluoric acid is so corrosive because the fluorine ion is highly reactive. Even so, it is not considered a 'strong' acid because it does not completely dissociate in water.
History of Use
Walter White and Jesse Pinkman first use hydrofluoric acid, stolen from the high school science lab, to dispose of the corpse of Emilio Koyama. However, Jesse disregards Walter's instructions about using a plastic container, instead choosing to pour the acid onto the body placed in a bathtub. This results in the acid dissolving through the bathtub and the floor, scattering Emilio's liquified remains into the hallway ("") and forcing Walt and Jesse to clean up the bloody mess. ("")
While it is not shown onscreen, it is assumed that the corpse of Emilio's cousin, Krazy-8, was disposed of in a similar fashion.
- Mike: "I've never used this stuff. Are you sure it will do the job?"
- Jesse: "Trust us."
- ―Jesse and Mike discussing dissolving Victor's corpse.[src]
Later, Walter, Jesse, and Mike Ehrmantraut use hydrofluoric acid to dissolve the body of Victor, who Gustavo Fring killed by slicing his throat with a box cutter. This time they are more successful, as they put Victor's body into a plastic barrel beforehand. Along with the body they dissolve the box cutter and the gun Jesse used to kill Gale Boetticher. ("")
- "So, what, is this going to become a regular thing, now? Meth cooking and corpse disposal? Jesus..."
- ―Walter White upon seeing the body in the laundry basket
Later, at Gustavo Fring's chicken farm, a sniper (Gaff) shoots and kills one of Gus's henchmen. Mike and Jesse take the unnamed henchman down to the superlab in a laundry basket, where Walt is waiting. Walt is shocked, but is told by Mike to grab a spare barrel. The barrel with the dissolved body is then later seen loaded onto a truck of hazardous materials ("").
In Season 5, Walter, Mike, and Todd Alquist use hydrofluoric acid to dissolve the corpse of Drew Sharp, a young boy shot by Todd after witnessing their train heist (""), to make sure he was never found by the authorities. The group also uses the acid to dissolve Drew's bike. Later in the season, Walt and Todd use hydrofluoric acid to dispose of Mike's body after Walt shot him in a fit of rage ("").
Hydrofluoric acid is classified as a weak acid because of its lower dissociation constant compared to the strong acids. It ionizes in aqueous solution in a similar fashion to other common acids:
- HF + H2O H3O+ + F−
It is the only hydrohalic acid that is not considered a strong acid, i.e. it does not fully ionize in dilute aqueous solutions.
When the concentration of HF approaches 100%, the acidity increases dramatically because of the following equilibrium:
- 2 HF H+ + FHF−
The bifluoride (FHF−) anion is stabilized by the very strong hydrogen–fluorine hydrogen bond.
Hydrogen fluoride gas is an acute poison that may immediately and permanently damage lungs and the corneas of the eyes. Aqueous hydrofluoric acid is a contact-poison with the potential for deep, initially painless burns and ensuing tissue death. By interfering with body calcium metabolism, the concentrated acid may also cause systemic toxicity and eventual cardiac arrest and fatality, after contact with as little as 160 cm2 (25 square inches) of skin.
- When Walter White goes to the school chemical storage to get hydrofluoric acid, we see that there are 6x1 gallon (22 litres) bottles of hydrofluoric acid. This is an enormous amount of hydrofluoric acid for a high school to have. Even universities generally don't need that much hydrofluoric acid. Why Walt's high school would carry that much HF is left unanswered.
- When using the hydrofluoric acid in the show to dispose of the bodies, the characters are shown to only wear gas masks and some protective clothing which do not cover their entire body. This sort of protection is completely inadequate when working with large amounts of hydrofluoric acid, as the HF fumes and airborne droplets will readily absorb through the naked skin, and will cause severe burns, poisoning and depending on the amount absorbed, death.
- The ability of hydrofluoric acid to dissolve organic matter was tested in MythBusters' Breaking Bad special, where Vince Gilligan appeared as guest star. The Mythbusters showed that hydrofluoric acid is not strong enough to completely break down organic material, calling this myth "Busted".
- Hydrofluoric acid on Wikipedia