As far as I know thermite is a typical redox reaction where $\ce{Al + Fe^{3+} -> Fe + Al^{3+}}$ happens. I guess the activation energy is very high, because you need to split the $\ce{Fe_2O_3}$ into $\ce{Fe^{3+}}$ and $\ce{O^{2-}}$. Probably you need molten aluminium too at $\pu{660°C}$ to ignite it.

I was wondering whether it is possible to ignite thermite in a water solution. Since $\ce{O^{2-} + H_2O -> 2OH^-}$, I guess a very acidic solution could help to start the reaction, since $\ce{OH^- + H^+ <=> H_2O}$. On the other hand it could mean a $\ce{2Al + 6H^{+} \rightarrow 2Al^{3+} + 3H_2\uparrow}$ reaction too.

Any idea whether thermite can be ignited this way, for example with a drop of concentrated acid? Or will it just result hydrogen gas, because that reaction has a lot lower activation energy?

  • $\begingroup$ Thermite I usually activated by extreme heat not chemically. And it is used in underwater welding, so yes it can be done is a liquid. $\endgroup$ – matt_black May 8 '18 at 12:06
  • $\begingroup$ Why do you think igniting water solution might work? $\endgroup$ – Mithoron May 8 '18 at 15:24

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