Find ΔH^0_f for OH(g): ΔH^{0}_{diss} Explained

[Dell]

find ΔH$$^{0}_{f}$$ for OH_(g) if

H₂O_{2 (g)}--> 2OH_(g)

ΔH$$^{0}_{diss}$$=213KJ/mol

what is ΔH$$^{0}_{diss}$$?? what is 'diss'

 

[Astronuc]

Most likely, diss = dissociation.

 

[Dell]

i don't think i have learned dissociation yet, unless it has another name??
so how would i solve this?