When writing a psa, it is not necessary to brainstorm because you already have all of the information from your persuasive essay.

YES it is very important to brainstorm

Spontaneity tell us the direction of the reaction, but not how fast it goes. gibbs free energy brings together enthalpy, entropy and temperature in one easy formula. g = h - ts. and, finally the sign of delta g is always negative for a spontaneous reaction.