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WeWW! CSI:New York... Where There's Smoke... Death by Caesium

posted Nov 16, 2016, 10:09 PM by Grace Ong   [ updated Dec 5, 2016, 10:17 PM ]
The following post was first posted on Blogger on Monday, 22 July 2013.

Episode 2 of CSI:New York Season 9 was an interesting one - a man ate a sandwich which was laced with caesium. He died minutes later because the caesium he swallowed exploded when it came into contact with the hydrochloric acid in his stomach.

CSI New York Season 9 Episode 2 - Leonard Brooks
The face of a murderer − Leonard Brooks
Hey! It's that same guy from Criminal Minds! Uber-geek Penelope Garcia's ex!

CSI New York Season 9 Episode 2 - Murder Victim
The poor victim, after swallowing part of the sandwich

There's no question about the explosion part, given the high reactivity of caesium, as demonstrated by the following video:

(Watch this video on YouTube.)

What's puzzling is − how did the caesium survive the trip from the deli to the park, where the man ate that lethal sandwich?

Let's see...
  1. I suppose caesium was chosen because it was the most reactive, non-radioactive Group 1 metal, and would present itself in a most dramatic fashion during the reaction with stomach acid.

    semi-solid caesium in a sealed glass ampoule
    (Source: Wikimedia Commons)
    The semi-solid state of caesium, near or at room temperature
     − This photograph is part of Dnn87's element collection.
    Click here to view the rest of his beautiful photographs.

  2. The melting point of caesium is 28.4 °C. The story did not seem to take place during summer, so I presume the surrounding temperatures were low enough for the metal to be in the solid state.
  3. Apparently, it was the mayonnaise in the sandwich that was laced with caesium. Is this even practical? The simplest homemade mayonnaise contains egg yolk, lemon juice and oil (e.g. olive oil), all of which contain substances that react with highly reactive caesium (gasp!).

    Water, for instance, reacts with caesium to give off hydrogen gas. As shown in the video above, the reaction is so exothermic that the hydrogen gas produced spontaneously ignites, causing an explosion that sometimes shatters the container!

    2Cs + 2H2O → 2CsOH + H2

    Under acidic conditions, the reaction becomes even more exothermic, so the citric acid in the lemon juice and the fatty acids present in the oil are going to make things worse!

    Examples of fatty acids present in olive oil
    structure of linolenic acid
          structure of oleic acid
    linolenic acid
    (Source: Wikimedia Commons)
          oleic acid
    (Source: Wikimedia Commons)

    structure of linoleic acid
    linoleic acid

    2RCO2H + 2Cs → 2RCO2Cs + H2
    2ROH + 2Cs → 2ROCs + H2

  4. Perhaps the caesium was still coated with a protective layer of unreactive mineral oil in the sandwich?
Maybe that was the case.

No, wait! Given that the caesium was placed between bread and other fillings that contain water, fatty acids and other substances that may react with it, all that 'friction' as the sandwich was being transported from the deli to the park would have rub any mineral oil off the metal. I think the sandwich would have started 'smoking' way before the victim took a bite of it.

I think I'm thinking way too much...