[soso lulu]

T   ∆H0   ∆S0   ∆G0
(K)   (kJ)   (J/K)   (kJ)
300   -133.932   -424.004   -6.731
305   -133.634   -423.02   -4.613
310   -133.339   -422.059   -2.501
315   -133.046   -421.123   -0.393320   -132.756   -420.209   1.711
325   -132.468   -419.316   3.81
330   -132.183   -418.445   5.904
335   -131.9   -417.593   7.994
340   -131.619   -416.761   10.08
345   -131.34   -415.948   12.162
350   -131.064   -415.153   14.239
355   -130.79   -414.375   16.313
360   -130.518   -413.614   18.383
365   -130.248   -412.869   20.449
370   -129.98   -412.14   22.512
375   -129.714   -411.426   24.571
380   -129.45   -410.726   26.626
385   -129.188   -410.041   28.678
390   -128.928   -409.371   30.727
395   -128.67   -408.713   32.772
400   -128.414   -408.069   34.814


The above data is taking from HSC program . For the urea production from 300-400 (K)

well , my qustion is that why ∆G0 from 300-315 has a negative sign ??

since i know that if S (-)  H and G should be (+)

please if anyone knows help me

because i want to know ??!!!

[Hunt]

since i know that if S (-)  H and G should be (+)

Im not so sure I understand what you mean. Usually for chemical rxns the relation ∆G = ∆H - T∆S is used to calculate the value of ∆G. In the temperature range you've shown the value of ∆S is negative and so is ∆H. So the sign of ∆G depends on the magnitudes of the enthalpy and entropy. Because |T∆S| < |∆H| the sign of ∆G is negative. As the temperature increases |∆H| decreases while |T∆S| increases so ∆G becomes positive after T=315K.