[crow_of_darkness]

    I know that you MUST NOT mix iodine with acetylene or ammonia. My question is why? Or better: WHAT will happen if you do this.
    Thanks

[limpet chicken]

I haven't read anything into the reaction with acetylene, but I have done the experiment with I2 and NH3, it forms a VERY unstable explosive compound, NI3.

The typical demo is preperation of a tiny crystal of the compound, leaving it to dry off from the ammonia, then touching with a feather on the end of a long stick, when it explodes with a crack and a plume of violet-colored iodine vapor.