Chemistry With Mr White
Yeah Mr White, Yeah Science!
A. J. Li
BREAKING BAD IS ONE OF THE GREATEST SHOWS OF ALL TIME, remaining popular despite over a decade having passed since its final episode aired. Although it is undoubtedly a crime drama show, there are still many educational bits thrown in from time to time which could potentially be relevant to an aspiring chemistry student.
Flame Tests
In the pilot episode, we see Walter White introducing the subject of chemistry with the typical spiel about how atoms combine to form molecules and compounds. He does, however, explain this with the aid of a couple of spray bottles and a Bunsen burner. He spritzes the flame with each of the bottles and the flame changes colour. He does not explain what is going on here but this is a great opportunity to learn about flame tests. What is probably in those bottles, are solutions containing specific metal cations. When metal cations are subjected to an input of energy, such as the flame of a Bunsen burner, some electrons can get excited into a higher energy state, before emitting photons when they drop back down to their ground state. The energy of the photon emitted when dropping down is unique to each element and corresponds to a colour that we then see. For example, the flame turns green after Walter spritzes it with one bottle, which likely means there were barium ions in that bottle as the colour matches barium’s energy absorption levels. Similarly, the red colour from the other bottle is likely to be strontium since that colour corresponds to the light emitted by strontium in a flame test. You will meet this concept in HSC Chemistry modules 1 and 8.
Walter Cooking. Source: Google
Chirality
In the very next episode, Walter introduces a concept called chirality. Now, as a chemistry student, I find it incredulous that supposedly the lesson after being introduced to what chemistry is, you are learning about chirality, which is a somewhat advanced concept in organic chemistry, particularly for high-school students. I think its purpose was more of a metaphor for Walter, which I will expand on later. As Walter says, the term “chiral” is derived from the Greek term for “hand.” It is referencing a group of stereoisomers that are mirror images of each other. That is, just like your hands, everything about them is the same, except that they seem to be flipped across an imaginary mirror. They are not the same and do not have the same properties since, just like your hands, you cannot superimpose one on top of the other despite how similar they may seem, because they are mirror images. Chiral compounds are often described as being “left-handed” or “right-handed” in another reference to the etymology of the word chiral and the simple analogy chirality has to our hands. The chirality of molecules does matter, none more evident than in the functioning of amino acids as most of them are chiral, and thus only one enantiomer (the left-hand or right-hand molecule) can fit into a biological system due to its ability or inability to be superimposed on another molecule. Back to the Walter metaphor, I believe the writers of the show were trying to portray Walter himself as chiral. On one hand he is a passionate chemistry teacher, but on the other, he is delving into the world of producing illicit substances. He is the “same” person but with two vastly different sides. Unfortunately, you will not meet this concept in HSC Chemistry as it is too advanced, however, you will meet similar concepts and the building blocks of chirality in module 7.
Building a Battery
After Walt and Jesse’s first successful cook, their ecstasy is cut short by the revelation that their RV’s battery has died. Eventually, Walt creates a small battery using chemistry to jumpstart the RV battery, but how did he do it? Basically, he made several Galvanic cells, the simplest form of a battery. He did this by making makeshift anodes and cathodes, separated by an electrolytic solution which would allow a current to flow through the system. In his case, mercuric oxide and graphite from brake pads formed the cathode. The anode was created by zinc, from anything such as galvanised steel. With potassium hydroxide as the electrolyte, he then uses a copper wire to conduct the electricity formed by the electron potential difference between the anode and the cathode and form a single galvanic cell. You will meet this concept in HSC Chemistry module 3.
Heisenberg Cooking. Source Google
The RV Chemistry
But what happened before the battery? Walt employed two different methods throughout his journey. He started with a simpler, easier method that was, however, more difficult to scale up. This involved using some readily available cold medication and some other common materials. He used red phosphorus, found on the sides of matchboxes to reduce elemental iodine to hydroiodic acid, a redox reaction you will encounter in module 3 as well. The hydroiodic acid itself is then used in another redox reaction with the cold medication, namely pseudoephedrine. The pseudoephedrine is reduced by the hydroiodic acid to yield the final product. These reactions combine several concepts from multiple modules, including modules 3, 5, 6, and 7.
However, later on in the show, it is no longer tenable to use this method as it is too hard and suspicious to get a lot of the cold medication. In essence, the medication was the limiting reagent in the previous method and reactions, a concept you will meet in module 2. Walt then devises an alternate pathway. He now uses P2P (phenylacetone) and methylamine, no more cold medication. P2P can be made from phenylacetic acid, which itself can be made from common chemicals including styrene, from polystyrene cups! In fact, a Year 12 chemistry student could probably devise a way to make the phenylacetic acid and it has been spotted as a question on some past papers. Anyways, the P2P and methylamine are condensed together and then reduced by adding hydrogen to yield the final desired product. This reaction is known as a “reductive amination.” Unfortunately, it is too advanced to be covered in the HSC Chemistry course, but many similar concepts are taught in module 7 and with some extracurricular study, you could probably understand the reaction as well. Thus concludes our educational journey in the world of chemistry. If any of the above concepts interests you and you want to learn more, be sure to consider choosing chemistry as one of your HSC subjects!