[HansonLoveFest]

Given the following data:

S + 1.5O2 --> SO3 Delta H = -395.2 kJ

2SO2 + O2 --> 2SO3 Delta H = -198.2 kJ



Calculate Delta H for the reaction

S + O2 --> SO2


I can't seem to work this out. I wind up with S -> SO2, but there's no mol of O2 left behind on the reactants side.

I reversed the 2nd equation/reaction and cut it in half, so the SO2 would cancel. I left the other one the same. This allowed the 1.5 mol O2 to cancel, as well as the SO2.

What am I missing?

[LQ43]

I reversed the 2nd equation/reaction and cut it in half, so the SO2 would cancel. I left the other one the same. This allowed the 1.5 mol O2 to cancel, as well as the SO2.

Do the math again, not all the O2 cancels.

[HansonLoveFest]

I'm sorry, I read the problem wrong. Stupid mistake. I saw the 1.5 O2 as .5 O2, which threw me off.