What is Hess’s Law?
The enthalpy change of a reaction is always the same, no matter which route is taken (as long as the initial and final conditions of the reaction remain the same)
Which way do the arrows point for reaction paths on enthalpies of combustion?
Down from reactants and products TO COMBUSTION PRODUCTS
Which way do the arrows point for reaction paths on enthalpies of formation?
Up from elements TO REACTANTS AND PRODUCTS