Please explain how to get to the answers, not just report the answer (I already
ID: 783496 • Letter: P
Question
Please explain how to get to the answers, not just report the answer (I already have the answer, but I need to know the math)
Consider the reaction
2NO2(g) -->N2O4(g)
Throughout the problem you can assume delta H and delta S are independent of temperature
A.
Calculate deta H, delta S, and delta G at 30C
B.
Explain, qaulitatively, why the sign of delta S makes sense.
C.
Is this process spontaneous at 30 C (please include more than yes or no)
D. At what temperature will te sign of delta G change?
Explanation / Answer
delta H = 9.16 -2*33.18 = -57.2 KJ/mol
Delta S = 304.29 -2*240.06 = -175.83 J/mol-K
Delta G = Delta H - T *Delta S
Delta G =- 57.2 *1000 + 175.83 *303 =- 3923.5 J/mol =- 3.93 Kj/mol
SIgn of Delta S is important here because at higher Temp. the Rxn is not spontaneous
the rxn is spontaneous when Delta G is negative
So it is spontaneous
When Delta G becomes 0 then the sign changes at that Temp
T = 57.2*1000/175.83 = 325.3 K = 52.3 C