Breaking Bad | Season 5 | Episode 5 | “Dead Freight”
“The methylamine keeps flowing,” intones Walt. “Nothing stops this train. Nothing.” But what if the train is full of methylamine? Then if you don’t stop it, the methylamine keeps flowing right on out of your territory. Time for a heist, with predictably unpredictable consequences.
Doing the methylamine maths
Walt and Jesse are bang on about the weight of the methylamine in the tanker, yo. The density of water is 998.21 kg m-3 (at 20 °C), and the density of a 40 % w/w solution of methylamine in water is about 890 kg m-3. Our team is boosting 1,000 US gallons of the solution, or about 3.79 m3. This will have a mass of about 3,373 kg, and will therefore need to be replaced by the same mass of water, which comes out to 3.38 m3 or 892 US gallons. Looks like Walt can do these sums even without his calculator watch.
Since the water is going in the top and the methylamine is coming out of the bottom, there’s a chance that the incoming water will mix with the original solution and dilute it as it’s going out of the bottom. With 24,000 gallons to play with, though, this effect is probably small enough to be discounted.
Are Walt’s mental dilution calculations also correct? 24,000 US gallons of 40 % w/w methylamine is 90.85 m3, or 80,857 kg of solution (of which 32,343 kg is methylamine). The company is losing 1,000 US gallons of solution, or 3,373 kg (of which 1,349 kg is methylamine) and gaining 900 US gallons (3.4 m3 / 3,394 kg) of water. After the heist, instead of having 32,343 kg of methylamine in 48,514 kg of water (total: 80,857 kg), they have 30,994 kg of methylamine in 49,884 kg of water (total: 80,878 kg). This difference in mass (0.03 %) is well within error ranges for industrial weighting scales (and quite a few laboratory ones too), and the new methylamine solution is only 38 % w/w (5 % loss). Genius!
This was a really fun episode (right up until the hammer-blow ending, at least) and I don’t want to detract from that too much, but so much could have gone wrong with the train heist. What if the methylamine tanker had been somewhere else on the train and not right over the bridge? What if the train hadn’t stopped in time (given that there weren’t any automatic warnings of things on the track)? What if one of the engineers got bored and looked back at the train? Given that there was only one shot at this, the Heisenberg crew took an enormous risk.
Mike floats the idea of going back to a pseudoephedrine cook, which Walt isn’t too happy about due to the lower production (and hence profit). This isn’t due to any inefficiency in the chemistry – in fact, the pseudoephedrine method should be a little more efficient due to there being fewer reaction steps – but probably reflects the difficulty of getting the precursor in any appreciable quantities.
First magnets, now siphoning out chemicals – Jesse is fast becoming the creative criminal genius behind Team Heisenberg.
Freight trains have incredibly long stopping distances (easily over 1.5 km), so I’m assuming that there has to be a clear line of sight to any level crossing with enough track to stop.
Was there any way to avoid killing the kid on the dirt bike? Sure, no witnesses – but could the team have passed themselves off as a construction/water crew? Expect a lot of yelling next week.
Elements in the credits
|Steven MicHael Quezada||Hydrogen|
|StewArt A. Lyons||Argon|