Given : S(s) + O2(g) --> SO2 (g) Delta H= -296.1 kJ 2SO3(g) --> 2SO2(g) + O2(g) Delta H= 198.2 kJ How to find the Delta H for :2S(s)+3O2(g) --> 2SO3(g)?

1 Answer
Mar 15, 2018

We want DeltaH^@ for..

2S(s) + 3O_2(g) rarr 2SO_3(g)

Explanation:

We gots...

(i) S(s) + O_2(g) rarr SO_2(g) ;DeltaH^@=-296.1*kJ*mol^-1

And...

(ii) 2SO_3(g) rarr2SO_2(g) + O_2(g) ;DeltaH^@=+198.2*kJ*mol^-1

And we take 2xx(i)-(ii)...

2S(s) + 2O_2(g) +cancel(2SO_2(g)) + O_2(g)rarr2SO_3(g)+ cancel(2SO_2(g))

.....the which gives...

2S(s) + 3O_2(g) rarr2SO_3(g)

DeltaH_"rxn"^@=(2xx-296.1-198.2)*kJ*mol^-1=-790.4*kJ*mol^-1