Formation Reaction States

[Ashwin Babu 1I]

When coming up with the formation reaction for a certain element, is there a consistent pattern with the states of matter of the reactants? For instance, if we wanted the formation reaction of HI, would we assume that the I₂ and H₂ are both in their gaseous phase, or are we unable to know that?

[Ashely_Pavon_2E]

There does not have to be a consistent pattern with the state of matter of the reactants.

[Sarah Egan 3A]

Typically assume that the reactants are in their standard states. In your example of hydrogen iodide, the standard state for hydrogen and iodine is gaseous at room temperature and pressure.
There may be times where theyre not in their standard states but those questions would probably specify