Complete and balance this decomposition reaction

Question

HI ==>

is this reaction
HI ==> H + I ?
or... HI ==> H2 + I2 ?
why?

Answer 1

Remember that H and I are diatomic. The diatomic gases are H2, N2, O2, F2, Br2, Cl2, I2 along with their cousins P4 and S8. Look at the periodic chart and find them. You can remember what they are by WHERE they are in relation to each other. H is the only one "out of pocket" but the others form a nice block.