Sign of the Gibbs for a reaction profile

[garrett_perozich]

When drawing a reaction profile given the equation, for example, CH3CHCH2 + HBr, how do we know whether the final Gibbs free energy will be lower or higher than the initial? We were asked to do this twice on the homework for chapter 4, once for Gibbs, and the other for potential, and both times I assumed that the final energy was lower than the initial, but is that always the case? If not, then how exactly would I determine whether it is or isn't given no numerical data?

[Eugenia Kwon 3O]

In this case we were given a specific example of the reaction HBr and Propene which is defined to have products that are in lower energy than reactants. For now the organic textbook only went through three examples for each type of reaction (electrophilic addition, aromatic substitution, and the SN2) so I assume we memorize the reactions for now.

[Chem_Mod]

You can assume these reactions are spontaneous so delta G will be negative.

[Linh Ngau 1F]

Will the reactions we be given always be spontaneous? Or will there be instances where we get a reaction that is endergonic as opposed to exergonic; is this fair game for the final?