My understanding of jury nullification is that it applies to a different scenario, typically that of when the jurors share the sentiment that the law the defendant is accused of violating is unjust (or is being unjustly applied). I don't feel like looking up the exact phrasing of the laws pertaining to "possession/discharge of a weapon on school grounds and discharging a destructive device" in florida, but I would guess they mention intent, or culpability [1]. So unless it comes to light that she was aware the chemical mixture she used would create an explosion, I think the charges will be dismissed or she will be acquitted by jury, without having to apply jury nullification.
But also, my thinking is that recently the US seems to want to trample down many "criminals" for basically downloading things that someone regrets them downloading. I worry about a future where DA's are overzealous about going after people without any mens rea and/or well after the victims of a crime have expressed no interest in continuing the case. Since, in the US, jails are intended to punish instead of rehabilitate and having a felony conviction takes away many of your rights I think they need to be far more careful who they level charges against.
Possession of "weapons" charges are in the jurisdiction I reside in strict liability, no intent to use them needs to be shown just the actus rea of possession is sufficient. [Claimed] Ignorance of the nature of the weapon is not a valid defence.
I know practically nothing of the charges or pertinent laws here mind you.
[1] http://en.wikipedia.org/wiki/Culpability