In the Eqn: [3 Fe + 2 O2 → Fe3O4], How many grams of Fe will be needed to react with 6.85 mol O2 ?

the answer is barium and copper bromide

i believe the answer is three water molecules

a). in this case, dh> 0 and sd> 0. if t becomes larger, the term "-tds" will become more negative. at some point, it is possible that -dts will be more negative than the dh is positive, and the reaction will become spontaneous. this is probably the correct answer, but you should look at all of the other possibilities and make sure of that.