So I am trying to solve a problem two different ways, and both ways get very different answers. One is right, one isn't. But I don't understand why one way works, and the other doesn't. Shouldn't they just get the same answer?
So here is the problem:
2H
2S(g) + 3 O
2 (g)
2H
2O (g) +2 SO
2 (g)
Using standard thermodynamic data at 298K, calculate the entropy change for the surroundings when 1.92 moles of H
2S(g) react at standard conditions.
So the correct way to solve this is by using: ΔS=ΔH/T
And you get: -287.9 J/k
However when I use the equation: ΣΔS=ΣS(products)+ΣS(reactants),
I end up getting -152.9
So why can't we simply use a entropy values to solve for ΛS instead of ΔS=ΔH/T?