Molecular moments in pop culture

 

Benzene on the big screen

It’s often a surprising delight when molecules crop up in pop culture. Earlier this year, while sitting in a theater watching the UK-based zombie thriller 28 Years Later, this horror-loving Newscriptster was tickled when benzene got a shout out.

Benzene’s big moment comes when Erik, a marooned Swedish soldier (played by Edvin Ryding), has just rescued the main characters—Isla (Jodie Comer) and Spike (Alfie Williams)—from people infected with a rage virus, who violently chase the mother-son duo into an abandoned gas station’s convenience store.

As soon as Isla enters the building, she starts choking on a layer of purplish gas swirling at eye level. Still, the two heroes push forward, desperate to escape their enraged pursuers. Then, when all hope seems lost, a stranger—Erik—opens a skylight, shouts to “get down,” and fires his rifle into the store at the infected. The building explodes. The infected burn to a crisp. Erik, Isla, and Spike walk away shaken but unscathed.

“What happened?” asks a stunned Spike.

“Benzene. Vaporized. Built up over the years,” Erik confidently replies.

It was a serious moment, but this Newscriptster couldn’t help but chuckle, appreciating the artistic license taken by representing a colorless gas denser than air as a buoyant, swirling purple haze. Then a question arose: Small amounts of benzene are present in gasoline, but could the molecule really be blamed for such an explosion?

Gasoline is made of hydrocarbons of varying lengths, including n-paraffins, isoparaffins, cyclic paraffins, olefins, and aromatics, says Suzanne Golisz, a petroleum chemist who has worked in the industry for over a decade. For the last century, “refiners have added antioxidants into their gasoline to prevent gum formation and keep the fuel stable,” she tells Newscripts.

But antioxidants can’t stabilize gasoline indefinitely. So, 28 years after societal collapse, “the things that would be reactive, like olefins, can start to form oligomers and polymers, which would end up being like a sticky residue,” Golisz says. However, “I can’t envision any way that you are making benzene just from the degradation of gasoline,” she adds.

Over the years, as large hydrocarbons became gummy, lightweight hydrocarbons would evaporate. But the gases wouldn’t accumulate in the nearby convenience store, Golisz says. “It would be underground, in a tank, that anything would potentially build up,” she says. Unconnected to the store, any vapors that escaped—which, in the early years of an apocalypse might include benzene—would simply float away, giving little opportunity for a cinematic explosion decades later. Sorry, Erik.

Chemistry takes the cake

Another, far friendlier pop culture export from the UK has delighted US-based audiences for years: the Great British Bake Off (known stateside as the Great British Baking Show). But even baking-savvy fans may have faced a cake apocalypse while replicating a recipe in the most recent season’s semifinal episode if they weren’t aware of kitchen chemistry.

The final four contestants were tasked with constructing a dazzling framboisier cake, topped with a sugar dome. To make the dome, the bakers needed to heat sugar, water, and glucose syrup to 150 °C. The high temperature forces most water to evaporate from the liquid sugar, which can then be poured onto plastic wrapped tautly over a bowl. With a metal cake ring and gentle pressure, the liquid sugar can be ballooned then cooled into a crystal-clear dome.

US-based bakers who may have tried the trick will have discovered that the most common type of plastic wrap in US homes is made from low-density polyethylene, which starts to melt at 105 °C. So instead of acting as a dome-forming flexible surface, the plastic wrap melts and the sugar falls right through, which results in a crystallizing puddle. But unsuccessful bakers are in good company with this season’s Bake Off contestants. Although the bakers’ cling film—likely made from higher-melting-point polyvinyl chloride—held, every sugar dome was a disaster.

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