Question

Apply the Free Energy equation to identify whether reactions with the following values of delta H and Delta S are spontaneous or nonspontaneous and whether they are exothermic or endothermic:

a. delta H = -128 kJ; delta S = 35 J/K at 500k

b. delta H = +67kJ; delta S= -140 J/K at 250k

c. delta H = +75 kJ; delta S = 95J/K at 800k

Answer #1

ΔH = -ve for exothermic reaction

ΔH = +ve for endothermic reaction

ΔG =-ve for spontaneous reaction

ΔG = +ve for non-spontaneous reaction

a.

ΔH = -ve (exothermic reaction)

ΔG = ΔH - T x ΔS

ΔG = (-128 kJ) - (500 x 0.035) = -128 - 17.5 = **- 145.5
kJ (spontaneous reaction)**

b.

ΔH = +ve (endothermic reaction)

ΔG = (+67 kJ) - (250 x - 0.14) = 67 + 35 = **+ 102 kJ
(non-spontaneous reaction)**

c.

ΔH = +ve (endothermic reaction)

ΔG = (+75 kJ) - (800 x - 0.095) = 75 + 76 = **+ 151 kJ
(non-spontaneous reaction)**

Use
gibb's free energy equation to calculate the delta G of a reaction
with the following values: 298.15 K, -.1434 kJ/molK (delta S),
-1104.14 kJ (delta H).

Calculate delta G at 82 C for reactions in which
a. delta H = 293 kj delta S = -695 J/K
b. delta H = -1137 kJ; delta S = 0.496 kJ/K
c. delta H = -86.6 kJ; delta S = -382 J/K

Calculate the change in Gibbs free energy for each of the
following sets of ?H?rxn, ?S?rxn, and T.
Part A ?H?rxn=? 115 kJ ; ?S?rxn= 248 J/K ; T= 295 K
Part B ?H?rxn= 115 kJ ; ?S?rxn=? 248 J/K ; T= 295 K
Part C ?H?rxn=? 115 kJ ; ?S?rxn=? 248 J/K ; T= 295 K Express
your answer using two significant figures.
Part D ?H?rxn=? 115 kJ ; ?S?rxn=? 248 J/K ; T= 565 K Express
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Given the following information,
calculate the standard Gibbs free energy of the reaction at 1455 K.
State if the reaction is spontaneous or nonspontaneous followed by
the temperature at which the reaction switches spontaneity if
applicable.
CaCO3(s) --> CaO(s) + CO2(g)
Given: Δ°H = 179.2 kJ , Δ°S = 160.2 J/K

From the values of ΔΗ and ΔS, predict which of the following
reactions would be spontaneous at 25oC. If the reaction
is nonspontaneous at 25oC, at what temperature would it
become spontaneous?
A) ΔH = 10.5 kJ/mol, ΔS = 30 J/K * mol
B) ΔΗ = 1.8 kJ/mol, ΔS= -113 J/K * mol

calculate the standard free energy change delta G for reaction
N2 (g) +3H2(g)—>2NH3
N2 delta H=0.00kj mol^-1s=+191.5J mol^-1K^-1
H2 delta H=0.00kj mol^-1,s = +130.6j mol^-1 k-1
NH3 delta H=-46.0kj mol^-1,s =192.5 J mol^-1 k-1
A. +112.3 kJ
B.-87.6kJ
C.-7.4kJ
D.-32.9 kJ
E.-151.1kJ

1)
Calculate the amount of energy in kilojoules needed to change
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constants may be useful:
Cm (ice)=36.57 J/(mol⋅∘C)
Cm (water)=75.40 J/(mol⋅∘C)
Cm (steam)=36.04 J/(mol⋅∘C)
ΔHfus=+6.01 kJ/mol
ΔHvap=+40.67 kJ/mol
Express your answer with the appropriate units.
2) Given the values of ΔH∘rxn, ΔS∘rxn, and
T below, determine ΔSuniv.
Part A
ΔH∘rxn= 90 kJ , ΔSrxn= 144 J/K , T=
304 K
Express your answer using two...

Complete the following reactions. Determine their Q-values in
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Gibbs free energy for H2O(l) is -237.13kJ/mol
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_____g
(d) How many kilojoules of heat are released when 11.5 g of
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