The Chemical Reaction that causes Iron to corrode in air is given by 4Fe + 3O2 -

Question

The Chemical Reaction that causes Iron to corrode in air is given by

4Fe + 3O2 --> 2Fe2O3

In which

DeltaHrxn = -1204kJ

DeltaSrxn = -217.1J/K

Part A

What is the standard Gibbs free energy for this reaction? Assume the commonly use standard reference temperature of 298K

For Part A i got 63491.8 kJ, but mastering chemistry answer was -1139 kJ. I have no idea how they got that answer, i will appriciate if u do explain how masterin chem got different answer than me.

Part B

What is the Gibbs free energy for this reaction of 5958K? Assume that DeltaH and DeltaS do not change with temperature.

Part C

At what temperatyre Teq do the forward and reverse corrosion reactions occur in quilibrium?

Please do show the calculations.

Qualitative Predictions about Entropy

Part A: Rank these systems in order of decreasing entropy. Greatest entropy to Least entropy

1 mol of Carbon tetrachloride (g) at 273K and 40L

1/2 mol of helium gas at 100K & 20L

1/2 mol of helium gas at 273K & 20L

1 mol of oxygen gas at 273K & 40L

1 mol of helium gas at 273K & 40L

1 mol of helium gas at 273K & 20L

1/2 mol of liquid helium at 100 K

Thanx!

Explanation / Answer

Delta_G = Delta_H - TDelta_S

Delta_S = 0.217 KJ/K

a.) DElta_G = -1204 KJ-298*(-0.217KJ)

Delta_G = -1139.33 KJ

b.) Delta_G = -1204-5958*(-0.217)

= 88.89 KJ

c.) For eqb. Delta_G = 0

T = Delta_H / Delta_S = -1204/ -0.217 = 5548.39 K

Entropy ranking: more temp more entropy (everything else constant)

more volume more entropy(everything else constant)

more moles more entropy(everything else constant)

small size less entropy(everything else constant)

liquid very less entropy

1.1 mol CCl4 at 273 40L

2.1 mol O2 at 273 40L

3.1 mol He at 273 40L

4.1 mol He at 273 20L

5.1/2 mol He at 273 20L

6.1/2 mol He 100K 20L

7.1/2 mol He liquid 100K

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