can a catalyst alone make a nonspontaneous reaction occur spontaneously? explain why or why not. can a catalyst alone make a nonspontaneous reaction occur spontaneously? explain why or why not. yes, the catalyst decreases the differential in gibbs free energy between products and reactants. no, the reaction will only become spontaneous if you increase the overall concentration of reactants and add a catalyst. yes, since the catalyst adds enthalpy to the system, it can make it spontaneous. no, a catalyst affects only the activation energy, not the overall change in gibbs free energy.