Gram for gram (or oz for oz), what is the most energetic/exothermic chemical reaction within these guidelines:

Question

1. Must involve exactly two distinct elements or compounds, of any state (solid, liquid, or gas).

2. Must NOT require a catalyst in any form, chemical, thermal, or otherwise. The reaction must happen at room temperature.

3. Must exist in some abundance. e.g. californium and kryptonite is not a good answer.

I WILL give the best answer to someone that lists credentials, even if its "science buff".

If it turns out to be toothpaste and baking soda, or something equally accessible, feel free to PM me the answer to keep children from blowing their hands off. I'll still make sure you get 10 points =D

Answer 1

I'll take a wild shot. The reaction between water and any alkali metal - best is caesium. I know the reaction is explosive. I don't know if this is the MOST exothermic but I suppose its right up there somewhere.
Cs + H2O -> CsOH + H2 (catches fire upon evolution).

Answer 2

Oxidising aluminium to give Al2O3 is the most exothermic reaction I know about. It's the reaction which powers the solid fuel boosters of the space shuttle. You ignite the aluminium dust and you've got a self-sustaining very hot reaction.