I'm interested in the mushroom cloud produced by a nuclear explosion: What is it made of?

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I know that the uranium fission reaction is the following (from this web page)

$$\ce{{}^{235}U + {}^1_0n -> {}^{95}Sr + {}^{139}Xe +2~{}^1_0n + 180~MeV}$$

I know that these elements are not stable and decay, so what is left over?

  • $\begingroup$ This topic seems much more complex than this - there are lots of possible products even in first fission (ones you added are only example), also most of the mushroom doesn't come from the bomb itself but from it's surroundings. $\endgroup$ – Mithoron Mar 11 '15 at 1:03
  • $\begingroup$ Maybe a rough estimation of the element that is on average most present in the cloud $\endgroup$ – Keith Mar 11 '15 at 1:15
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    $\begingroup$ OK, I'll bite on the rough estimate - nitrogen from the air. For elements not in the air to begin with, mainly silicates from the ground. $\endgroup$ – Jon Custer Mar 11 '15 at 13:12
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    $\begingroup$ en.wikipedia.org/wiki/Mushroom_cloud $\endgroup$ – Mithoron Mar 11 '15 at 18:36
  • $\begingroup$ Fission or fusion ? $\endgroup$ – blacksmith37 May 9 '18 at 19:58

According to The Preparatory Manual of Explosives, the mushroom cloud is produced by the partial vacuum left after initial expansive shock wave. That implies that it is primarily the condensation of water that makes it visible. These clouds form in high explosive as well as in nuclear detonations near the ground. See https://books.google.com/books?id=J55D3HcgPuoC&pg=PA98#v=onepage&q&f=false.


During the cold war the americans did some work on the chemical form of fallout, the great problem is that shortly after a surface burst or a burst close to the gound the bomb will stir up whatever was close to the detonation or on the ground below it.

The heat of the bomb will cause the dust and other matter to rise up into the firey hot cloud of smoke mixed with fission and activation products together with unused fuel. The nature of the "dust and other matter" depends greatly on the detonation site.

When the detonation site was a coral island then the fallout tended to contain calcium oxide particles from coral plus some iron from the towers which held the bombs. Some of the particles collected were dicalcium ferrite (Ca2Fe2O4). A moderate yeild tower shot in the Nevada test site would give instead glassy spheres. Small yeilding surface shots in the Nevada site gave particles which were partly melted mineral grains.

The chemistry of fallout from underwater explosions was different again, if you want to read more then see C.E. Admans, N.H. Farlow and W.R. Schell, Geochimica et Cosmochimica Acta, 1960, volume 18, pages 42 to 56.


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