I'm sure we've all envisioned bombs made by allowing macroscopic quantities of antimatter to react with ambient matter thereby releasing vast quantities of energy in very short time scales. I'm wondering how realistic this actually is. Suppose I have a 1 kg chunk of anti-iron in the middle of my living room. I can imagine a scenario where the reaction with air at the surface creates enough radiation pressure to push most of the air away until an equilibrium is reached and the iron and air react at a constant rate. Similarly the reaction with my floor creates enough radiation pressure to hold the iron slightly aloft thus reducing the reaction rate. Considering the vast amounts of energy that would be contained in kg of antimatter (and the corresponding kg of matter), I'm wondering if this scenario could just make my living room very hot for a long time rather then instantly blowing up. For that matter could something similar happen on atomic scales. For example an atom of anti-iron meets an atom of nitrogen, 1 proton and 1 antiproton annihilate, and the resulting carbon and anti-manganese are pushed away from each other?