The element oxygen was prepared by Joseph Priestley in 1774 by heating mercury (II) oxide.
 HgO(s) --> Hg(l) + 1/2O2(g) ΔH° = 90.84 kJ
 Use the data given below to determine DS = and the temperature, at which this reaction will become spontaneous under standard conditions.
 S°(Hg) = 76.02 J/K· mol
 S°(O2) = 205.0 J/K· mol
 S°(HgO) = 70.29 J/K· mol