Question

What is the Gibbs free energy for this reaction at 3652 K ? Assume that AH and AS do not change with temperature, Express your answer to two decimal places and include the appropriate units. View Available Hint(s) AG = Value Units Submit Part At what temperature T do the forward and reverse corrosion reactions occur in equilibrium? Express your answer as an integer and include the appropriate units. View Available Hint(s) T., Value Units Submit

Answer 1

Equation to be used:

ΔG = ΔH – TΔS                

( ΔG = Gibbs free energy change, ΔH =Enthalpy change, T = Temperature, ΔS = entropy change)

Part B:

ΔH°rxn = -1684 kJ

ΔS°rxn = -543.7 J/K = -0.5437 kJ/K                            [1000J = 1kJ]

T = 3652 K

Putting the values in the equation, we get:

ΔG = ( -1684 kJ ) – (3652 K)( -0.5437 kJ/K)

Or, ΔG = 301.59 kJ

Part C

At equilibrium, ΔG° = 0.

So, at equilibrium ΔH°= Teq ΔS°

Putting the values :

-1684 kJ = Teq (-0.5437 kJ/K)

Or, Teq = 3097 K

(Here, the value of ΔH and ΔS used have been same throughout since it is mentioned that they do not change with temperature.