g-chem question (free energy change)

[CSU Undergrad]

Ive been stuck on this question

NH4Cl(s)-------->NH3(g) + HCl(g)

deltaH*=+176 kJ, and deltaG*= +91.2 kJ at 298K. What is the value of deltaG at 1000K.

The answer is -109kJ, can anyone explain to me how to go about in solving this, thank you.

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[sajjy]

Ive been stuck on this question

NH4Cl(s)-------->NH3(g) + HCl(g)

deltaH*=+176 kJ, and deltaG*= +91.2 kJ at 298K. What is the value of deltaG at 1000K.

deltaG = deltaH - T*deltaS]

deltaH and deltaS will be same at both temperature.
deltaS = 0.28456
plug this value in the formula at T=1000K

 

[Corky Cacas]

Ive been stuck on this question

NH4Cl(s)-------->NH3(g) + HCl(g)

deltaH*=+176 kJ, and deltaG*= +91.2 kJ at 298K. What is the value of deltaG at 1000K.

The answer is -109kJ, can anyone explain to me how to go about in solving this, thank you.

I agree. the answer is -110, how: well look

Delta G= Delta H - T Delta S

SO from what is given:
91.2=176-298 delta S From here we will fine delta S
Delta S=0.28

and plug it in the formula for 1000K instead of 298. look:

Delta G= 176 - 1000(0.28)

Delta G: -110 so the rxn is spontaneous.

 

[CSU Undergrad]

okay so entropy and enthalpy stays the same whether under standard conditions or not, thank you guys very much