H2 + i2 < => 2hi + 3 kcal

the formation of would be favored by the addition of heat.

a) reactants
b) products

I believe the correct answer would be reactants. When heat is added to the reaction mixture, the formation of reactants would be favored since the reaction is an exothermic reaction. Hope this answers the question. Have a nice day.

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.