[kentucky_girl]

What am I doing wrong on this problem?

H2(g) + F2(g) --> 2HF(g)
Assuming neither the enthalpy change nor the entropy change varies with temperature, calculate G at 283 K if the reaction mixture consists of 2.0 atm of H2, 3.2 atm of F2, and 0.14 atm of HF.

Here's my work:

[Note: I found the values for deltaH and deltaS in the appendix of my textbook]

deltaG = deltaH - tdeltaS + RTln(Q)

Q= [HF]^2/([F2][H2]) = (.14)^2/(2*3.2) = .0030625
deltaH = [2(-268.61) - (0 + 0) = -537.22 kJ
deltaS = (173.51) - (130.58 + 202.7) = -159.77 J = -.15977 kJ

deltaG = -537.22 - (283)(-.15977) + (.008314)(283)(ln(.0030625))
= -505.6246875

This is incorrect, and I can't figure out why...

[M:B]

Check your stoichiometry in the calculation of ΔS