Since you are taking 1.5 moles of gas and making 1 mole of gas, the entropy of the system has decreased: there are fewer ways of ordering the gas molecules. We expect then that DS is negative, this sort of favors the reactants.
Since DH is also negative, that would mean that the products have less energy than the reactants, so the enthalpy term would favor the products.
Overall, this reaction would be spontaneous at low values of T. The spontaneity (or free energy) of the reaction is based on DG = DH - TDS. If DG < 0, we say the reaction will occur.