One of the possible initial steps in the formation of acid rainis the oxidation of the pollutant SO2 to SO3 by the followingreaction: SO2(g) + 1/2 O2(g) -> SO3(g) The reaction isexothermic, meaning that it is spontaneous at lower temperatures,but becomes nonspontaneous at higher temperatures. At whattemperature does it change from being spontaneous tononspontaneous?
Molecule ΔHf (kJ/mol) @ 25°C S (J/molK) @ 25°C
SO2(g) -296.8 248.2Â Â
SO3(g) -395.7 256.8
503 K
1052 K
98.7 K
99.1 K
