Question

what is the difference between these two equation:
delta G= delta H-T(delta S)
and deltaG(knot)=delta H(knot)-T(delta S knot)

Which G do i use to tell whether the reaction is spontaneous

Answer 1

The first delta G is for a general reaction at the specified conditions. The delta G^o is a "standard delta G as 25 C" when using delta Hformation at 25 and delta Sformation at 25C.
(I assume knot means naught).
Delta G is the one to use for spontaneity but remember delta G is zero when the system is at equilibrium.