[steplock]

red phosphorus and iodine ??

Hmmm... I wish I could remember all the way back to chem 101 and remember how to combine these --- on paper of course.

[Beaker]

I wish I could remember all the way back to chem 101 and remember how to combine these --- on paper of course.
2P + 3I2 --> 2PI3
Red Phosphorus when combined with Iodine, forms Phosphorus tri-iodide. It's a fairly strong exothermic (heat releasing) reaction.