Question about the rules of thermodynamics

[samy4408]

Hello , we learned in thermodynamics that to calculate ΔHr °(of the reaction ) using ΔHf °(standard heat of formation ), we have to respect that
ΔHf °=ΔHr ° of a reaction forming 1 mol of compound from pure elements in their most stable form at standard state .
the problem is when we want to calculate ΔGr ° using ΔGf ° is it necessary to respect the rule raised before ?
thanks .

 

[Chestermiller]

Yes.