Question

Please show all work so that i can get a better understanding

A.) Estimate ΔG°_rxn for the following reaction at 449.0 K.

CH₂O(g) + 2 H₂(g) → CH₄(g) + H₂O(g) ΔH°= -94.9 kJ; ΔS°= -224.2 J/K

a.	+12.9 kJ
b.	-4.2 kJ
c.	+5.8 kJ
d.	-101 kJ
e.	+2.4 kJ

B.) Which of the following statements is TRUE?

a.	Endothermic processes decrease the entropy of the surroundings, at constant T and P.
b.	Exothermic processes are always spontaneous.
c.	Endothermic processes are never spontaneous.
d.	Entropy is not a state function.
e.	None of the above are true.

C.) Calculate ΔG_rxn at 298 K under the conditions shown below for the following reaction.

2 Hg(g) + O₂(g) → 2 HgO(s) ΔG° = -180.8 kJ

P(Hg) = 0.025 atm, P(O₂) = 0.037 atm

a.	-154.4 kJ
b.	-164 kJ
c.	+207 kJ
d.	-26.5 kJ
e.	+60.7 kJ

D.)Above what temperature does the following reaction become nonspontaneous?

FeO(s) + CO(g) → CO₂(g) + Fe(s) ΔH= -11.0 kJ; ΔS = -17.4 J/K

a.	298 K
b.	191 K
c.	632 K
d.	This reaction is nonspontaneous at all temperatures.
e.	This reaction is spontaneous at all temperatures.

Answer 1

A)

CH₂O(g) + 2 H₂(g) → CH₄(g) + H₂O(g) ΔH°= -94.9 kJ; ΔS°= -224.2 J/K

dG = dG - T*dS = (-94.9) - (298)(-224.2/1000) = 5.7658 kJ/mol

B.) Which of the following statements is TRUE?

a. Endothermic processes decrease the entropy of the surroundings, at constant T and P. True, since they decrease Heat in surrounding

b. Exothermic processes are always spontaneous. --> False, impossible to determine without dG

c. Endothermic processes are never spontaneous. --> False, impossible to determine without dG

d. Entropy is not a state function. --> False, it is

e. None of the above are true. --> False, at least one was

C.) Calculate ΔG_rxn at 298 K under the conditions shown below for the following reaction.

2 Hg(g) + O₂(g) → 2 HgO(s) ΔG° = -180.8 kJ

P(Hg) = 0.025 atm, P(O₂) = 0.037 atm

dG = dG° + RT*ln(Q)

dG = (-180.8*10^3) - (8.314*298)*ln((0.025^2)(0.037))

dG = -154352.91915

dG = -154.35 kJ/mol

D.)Above what temperature does the following reaction become nonspontaneous?

FeO(s) + CO(g) → CO₂(g) + Fe(s) ΔH= -11.0 kJ; ΔS = -17.4 J/K

dG = dH - T*dS

dG < 0 so

dH - T*dS < 0

dH/dS < T

-11000 / -17.4 < T

T = 632 K