The science of Breaking Bad: Cat’s in the Bag

Breaking Bad : Season 1 : Episode 2 : “Cat’s in the Bag”

Jesse attempts chemical disincorporation.

Jesse attempts chemical disincorporation.

Scrambling to deal with the fallout from their encounter with the local drug dealers, Walt and Jesse again turn to chemistry. In this post, I’ll be talking about chirality and how to dispose of a body with hydrofluoric acid.

You can read more about this episode at AMC, IMDb and the A.V. Club.

Chirality

Chirality - the two molecules are non-superimposable mirror images

Chirality - the two molecules are non-superimposable mirror images

In this episode’s school class, Walt is talking about chirality – a key concept in organic chemistry and an extremely important consideration in living systems. We usually say that chiral molecules are related as an object and its non-superimposable mirror image (this is written on the blackboard).

The most common example (which Walt gives) is that of your hands. You left hand and right hand are mirror images of each other, but they cannot be superimposed – no matter how you arrange your hands, you cannot align all the parts (fingers, palm, back, thumb etc.) exactly. Many molecules are the same – they exist as two enantiomers, which can have very different properties.

Also on the board behind Walt is an example of a chiral complex ion (a molecule with a central metal ion and weak bonds to several small molecules). We would write it as [Co(en)2(NH3)Br]2+ (en is shorthand for ethylene diamine; H2NCH2CH2NH2) – it is chiral even though the central Co ion has six bonds (rather than the four we’re used to with carbon).

Chirality in a complex ion

Chirality in a complex ion

Thalidomide

Thalidomide

Walt gives a tragic example of different enantiomers having different properties – that of thalidomide. While one enantiomer of the thalidomide molecule is an effective antiemetic (substance that prevents nausea), the other is a powerful teratogen (substance that causes developmental defects). When the drug was first sold in the 1950s, both enantiomers were present (called a racemic mixture) and pregnant women who took it to prevent morning sickness found that their children were born with severe deformities. Even if only the “safe” enantiomer is taken, the molecule will convert to a racemic mixture in the body.

Levomethamphetamine

Levomethamphetamine

Methamphetamine, the drug around which this season revolves, is also chiral. Only one enantiomer is an addictive psychostimulant; the other (levomethamphetamine) is a decongestant found in products like Vicks Inhaler.

For background information on this topic, see the primer on chirality.

Hydrofluoric acid

Hydrogen fluoride

Hydrogen fluoride

With a dead body about to stink out the RV, rather than dump it (where it may be found) Walt decides to dissolve it in some highly corrosive solution. His chemical of choice is hydrofluoric acid (HF), several litres of which the school supply room just happens to have lying around. This in itself is extremely unusual, as the stuff is so dangerous it would most likely never be used in high school experiments.

Polyethene

Polyethene (polyethylene)

Perhaps predictably, Jesse ignores Walt’s instructions to find a large plastic container (the LDPE ones he is looking at are made of low-density polyethylene) and attempts to dissolve the body in the bath upstairs. This kind of body disposal has been done before, but not in a standard domestic bath-for-bathing-in. As Walt later remarks, HF is highly corrosive and will eventually dissolve just about anything except plastics.

Presumably the chemical store would also have had other acids and bases around which would have been just as effective and not so dangerous and difficult to handle. It’s not clear to me why Walt would have opted for HF over the alternatives, but we can’t expect him to do everything perfectly on the first try.

Elements in the credits

Breaking Bromine
Bad Barium
Created Chromium
Bryan Cranston Bromine
AnNa Gunn Sodium
AAron Paul Argon
DeaN Norris Nitrogen
Betsy Brandt Beryllium
RJ MitTe Tellurium
Max ArchInega Indium
LynNe Willingham Neon
Robb Wilson King Tungsten
Reynaldo Villalobos Rhenium
Dave Porter Polonium
Sharon Bialy Sulfur
SherrY Thomas Yttrium
Melissa Bernstein Beryllium
StewArt Lyons Argon
Patty Lin Protactinium
Mark JOhnson Oxygen
Karen Moore Molybdenum
Vince Gilligan Vanadium
Adam Bernstein Beryllium
Advertisements

6 Responses to The science of Breaking Bad: Cat’s in the Bag

  1. aritali says:

    Reblogged this on aritali and commented:
    I know it may seem lame, but I am currently learning about enantiomers, non-superimposable, and chiral molecules in my Organic Chemistry class. I specifically have a quiz over the drug Thalidomide tomorrow morning, and interestingly enough, my nerdy side showed this concept of Chirality and how mirror images of the same molecule being non-superimposable therefore potentially causing horrible and undesired effects such as the birth defects that Thalidomide caused in the 1950’s decided to show my boyfriend this fact with my Organic Chemistry model kit just last week. Interestingly enough, apparently this exact drug and concept came up in a show he watches called “Breaking Bad.” Hmm… This sure did make me want to look into the show myself! Gosh, why am I so nerdy?

    • John says:

      One of the best shows on television, without a doubt. The episodes vary in amount of science content, though – there’s a lot of street-slinging and organised crime as the series progresses.

  2. […] Weak Interactions – The Science of Breaking Bad (explores all the science elements of this episode–chirality, hydroflouric acid dissolution, LDPE plastic, etc). […]

  3. Bob roberts says:

    Hydrofloric acid is chosen vs other acids because it dissolves calcium carbonate, the component of bones. Using other acids would only dissolve the soft portions leaving bones intact, which could be traced to the person from dental records. Hydrofloric acid does this because it has a small size, fewer protons present means it doesn’t repel its negatively charged electron cloud as far, allowing it to fit between bonds in calcium carbonate, glass, and ceramic (such as bathtubs), compared to hydrochloric acid (HCl) it is many times smaller molecule measured by its e- cloud.

  4. jon says:

    Hf would be a bad choice for this job, but the fact it attacks glass makes for this drama. HF does not dissolve meat so well, as seen on the myth budgets episode, but it binds to calcium to kill cells. The calcium depletion will disrupt the nervous system and the heart causing death.

    All strong acids will attack the calcium phosphate and calcium carbonate in bones and shells and dissolve them. They will also hydrolysis proteins causing the factional dissolution of tissue. Concentrated sulfuric is great at this because it is also arthroscopic and will bind with the water and get hot. Add an o oxidizer like perchloric acid and it gets nastier -I worked in a lab that dissolved whole fish with this stuff.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: