"Tridecyl hydride" = "marsh gas"?! _The Sweetness at the Bottom of the Pie_

[OmniSnert]

I've just finished reading Alan Bradley's mystery novel _The Sweetness
at the Bottom of the Pie_. The narrator is an 11-year-old girl who's a
prodigy in chemistry with a passion for poisons, as she describes
herself, and for the most part the chemistry in the book seems to be
correct.

One exception caught my eye. At one point, the narrator comments that
"There were thirteen carbon atoms in tridecyl, whose hydride was marsh
gas." The only "marsh gas" I'm aware of is primarily methane, with some
other minor components also of low MW. The only tridecyl I'm aware of
would be the C13H27- group, whose hydride would be tridecane, C13H28. My
on-line searches aren't turning up any other options. Is this an error
on the part of the narrator and/or author?

Another bit of chemistry that I'm not able to figure out is a
description of the late uncle who left behind the laboratory in which
the narrator does her work. "It was rumored that he had been studying
the first-order decomposition of nitrogen pentoxide. If that was true,
it was the first recorded research into a reaction which was to lead
eventually to the development of the A-bomb." What's the connection
between N2O5 and atomic bombs?

[Martin Brown]

Post by OmniSnert
I've just finished reading Alan Bradley's mystery novel _The Sweetness
at the Bottom of the Pie_. The narrator is an 11-year-old girl who's a
prodigy in chemistry with a passion for poisons, as she describes
herself, and for the most part the chemistry in the book seems to be
correct.
One exception caught my eye. At one point, the narrator comments that
"There were thirteen carbon atoms in tridecyl, whose hydride was marsh
gas." The only "marsh gas" I'm aware of is primarily methane, with some
other minor components also of low MW. The only tridecyl I'm aware of
would be the C13H27- group, whose hydride would be tridecane, C13H28. My
on-line searches aren't turning up any other options. Is this an error
on the part of the narrator and/or author?

I think so. Anything that heavy would be a light oil not a vapour.
Anything beyond 12 carbon atoms doesn't usually have much vapour
pressure. Octane is nominally the ideal petrol fraction and kerosene is
around 12. 15 or more carbon atoms and is more likely to be a wax!

Marsh gas is mostly methane but with a trace of phosphine in it that can
be phosphorescent and so alarms the yokels in the fens.
See for example:

https://www.chemistryworld.com/podcasts/phosphine/3007120.article

Recent detection of phosphine in Venus atmosphere caused something of a
stir because it could indicate life of some sort.

https://www.nature.com/articles/s41550-020-1174-4

I see now it has been partially retracted...

Post by OmniSnert
Another bit of chemistry that I'm not able to figure out is a
description of the late uncle who left behind the laboratory in which
the narrator does her work.  "It was rumored that he had been studying
the first-order decomposition of nitrogen pentoxide. If that was true,
it was the first recorded research into a reaction which was to lead
eventually to the development of the A-bomb." What's the connection
between N2O5 and atomic bombs?

It is just about conceivable that one of the high explosives they used
in the shaped charges for implosion weapons used N2O5 in its synthesis.
But UF6 and actinide separation chemistry played a much bigger part...

N2O5 its own Wiki page as "anhydrous nitric acid" / "powerful oxidiser".
I think it would be far too volatile for anyone without a death wish to
use in the manufacture of high explosives but I could be wrong.

https://en.wikipedia.org/wiki/Dinitrogen_pentoxide

Physics obviously played a much bigger part...

[OmniSnert]

Post by Martin Brown

Post by OmniSnert
Another bit of chemistry that I'm not able to figure out is a
description of the late uncle who left behind the laboratory in which
the narrator does her work.  "It was rumored that he had been studying
the first-order decomposition of nitrogen pentoxide. If that was true,
it was the first recorded research into a reaction which was to lead
eventually to the development of the A-bomb." What's the connection
between N2O5 and atomic bombs?

It is just about conceivable that one of the high explosives they used
in the shaped charges for implosion weapons used N2O5 in its synthesis.
But UF6 and actinide separation chemistry played a much bigger part...
N2O5 its own Wiki page as "anhydrous nitric acid" / "powerful oxidiser".
I think it would be far too volatile for anyone without a death wish to
use in the manufacture of high explosives but I could be wrong.
https://en.wikipedia.org/wiki/Dinitrogen_pentoxide
Physics obviously played a much bigger part...

All that I could think of was that it could be used to convert hydrated
uranyl nitrate to anhydrous uranyl nitrate (+ nitric acid). React that
with fluorine and get UF6, N2, and O2. I don't know if it would be
particularly useful to not have HF as a side product there.

[Martin Brown]

Post by OmniSnert
All that I could think of was that it could be used to convert hydrated
uranyl nitrate to anhydrous uranyl nitrate (+ nitric acid). React that
with fluorine and get UF6, N2, and O2. I don't know if it would be
particularly useful to not have HF as a side product there.

I think that is rather unlikely. Whilst SF6 is unbelievably inert. UF6
is a horrible nasty toxic compound that decomposes into HF in damp air.

HF is one of the few chemicals where the safety film about handling it
is known to cause casualties in the audience as people pass out!