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.

[1] http://en.wikipedia.org/wiki/Culpability